Biology unit 5 topic 7

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  • Created by: Sabina
  • Created on: 30-03-16 11:02
What is the role of muscles?
To bring about movement at a joint
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What is a joint?
A site where two or more bones are joined together
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How is movement produced?
By the coordinated action of several muscles
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What is an antagonistic pair?
A pair of muscles that move the bone it is made up of an extensor and a flexor
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What is an extensor?
Muscle that contracts to cause extension of a joint
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What is a flexor?
A muscle that contracts to reverse the movement of n extensor
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Why are muscles in antagonistic pairs?
Muscles cannot extent themselves (they can only pull they cannot push) and so need opposing muscle in order to extent.This allows control of movement
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Give an example of an antagonistic pair
When flexing your knee your hamstring muscles at the back of the thigh contract and the quads at the front of the muscle relax and so are stretched. To extend the knee, the quads contract whilst the hamstrings relax
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What is the role of a tendon?
Attaches muscles to the bone,enabling the muscles to power movement in the joint
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What is the role of a ligament?
Joins bone to bone and controls/restricts the amount of movement in the joint
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What is the role of the cartilage?
Protects bones within joints, acting as a shock absorber and absorbs synovial fluid
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What is the role of synovial fluid?
Acts as a lubricant
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What is the role of fibrous capsules?
Encloses joints
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Give examples of synovial joints
Hip, knee and ankle joints
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What is a ball and socket joint?
A round head fits into a cup shaped socket e.g. the hip
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What is a gliding joint?
Surface of a bone that makes normal direct contact with another bone as part of a synovial joint.
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What is a hinge joint?
A joint in which the a convex part of one bone fits into a concave part of another, allowing motion in only one plane e.g. the elbow
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What is a pivot joint?
Part of one bone fits into a ring shaped structure and allows rotation e.g. joint at the top of the spine
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What are muscles made up of?
Bundles of muscle fibres (each fibre is a single muscle cell)
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What is meant by multinucleate?
Each muscle cell contains several nuclei
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Why is a muscle cell multinucleate?
Because a single nucleus could not effectively control the metabolism of such a long cell
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How is an elongated muscle fibre formed?
During prenatal development, several cells fuse together forming an elongated muscle fibre
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What is the arrangement of muscle fibres within muscles?
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What is the sacrolemma ?
The membrane surrounding a muscle fibre
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What is the sacroplasm?
The cytoplasm of a muscle fibreW
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What are myofibrils made up of?
A series of contractile units called sacromeres
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What is the name of the two types of protein molecules that that make up the sacromere?
Thin filament-->actin Thick filament-->myosin
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What is the role of transverse (T) tubule?
Helps spread electrical impulses through the sacroplasm so they can reach all parts of the muscle fibre
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What happens once calcium binds to a troponin molecule?
Causes troponin molecule to move causing tropomyosin to be moved/displaced
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What is exposed when tropomyosin moves?
Myosin binding site on actin filament
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What happens when the myosin head binds with the myosin binding site on the actin filament?
ADP+Pi are released. The leads to the myosin changing shape causing the myosin head to nod forward. This results in the relative movement of the filament
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What happens when an ATP molecule binds to the myosin head?
Causes the myosin head to detach and an ATPase on the myosin head hydrolyses the ATP, forming ADP and Pi. The myosin head returns to its original position and the cycle starts again
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What happens after the muscle relaxes in sliding filament theory during rigor mortis?
As there is no ATP present the cross-bridges remain attached. Calcium ions cannot be pumped out of the muscle sacroplasm . As a result troponin and tropomyosin don't move back.
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What is the definition of BMR?
Basal metabolic rate-A measure of the minimum energy requirement of the body at rest to fuel basic metabolic processes
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How is BMR measured?
Oxygen consumption is recorded under strict conditions; no food is consumed for 12 hours before the measurement,with the body totally at rest in a thermostatically controlled room
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What factors can result in variations in BMR?
Percentage of body fat (women usually have higher percentage of body fat), age and gender
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What are the two main energy sources?
Carbohydrates and fats, which have either just been absorbed from the gut or have been stored around the body
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What is respiration?
A series of enzyme-controlled reactions
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How is ATP in water produced?
In solution phosphate ions are hydrated. To make ATP phosphate needs to be separated from the water molecules
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What is ATP made up of?
Adenine,ribose sugar and 3 phosphate groups
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What reaction occurs in order to split ATP
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During what process is lactic acid produced
Fermentation during anaerobic respiration
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Where does the Krebs cycle take place?
In the mitochondrial matrix
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Where is the electron transport chain?
On the mitochondrial inner memebrane
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What happens during low intensity exercise?
Enough oxygen is supplied to cells to enable ATP to be regenerated through aerobic respiration of fuels
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Describe carbohydrate oxidation
Hydrogen stored in glucose is brought together with oxygen to form water. During this reaction energy is released when the bonds in CO2 and H20 form.This energy can be used to generate ATP.
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Why can't glucose and oxygen be brought together directly during carbohydrate oxidation?
Cannot be brought together directly as this would release a large amount of energy quickly which could cause damage to the cell.
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What is the name of the initial stage of carbohydrate breakdown?
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Where does glycolysis occur?
In the cytoplasm
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Where is glycogen stored?
In muscle or liver cells
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What are the main stages of glycolysis?
Glycogen-->Glucose-->2 phosphate groups added to glucose one from each ATP allowing it to be split into a 3C intermediate-->Each intermediate is oxidised into a pyruvate molecule
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What happens to pyruvate during the link reaction?
Pyruvate is: DECARBOXYLATED (CO2 is released as a waste product) and DEHYDROGENATED (Two hydrogens are removed and taken up by the coenzyme NAD and are later used to form ATP). The resulting 2C molecule combing with coenzyme A to form acetyl coA
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What happens during the Krebs cycle?
Each acetyl CoA combines with a 4C compound to form a 6C compound-->
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What does Acetyl CoA combine with in the first part of the Krebs cycle?
Combines with a 4C compound to form a 6C compound
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What happens to the 6C compound in the Krebs cycle
CO2 and 2H are removed to form a 5C compound.The hydrogen is taken up by coenzyme NAD to form NADH
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What happens to the 5C compound in the Krebs cycle?
CO2, ATP and 3x 2H are removed this causes coenzymes FAD and 2x NAD to be reduced causing the 4C compound to be regenerated
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What is the role of the reduced coenzymes in aerobic respiration?
The reduced coenzyme shuttles the hydrogen atoms to the electron transport chain on the mitochondrial inner membrane. Each hydrogen atom's proton and electron separate, with the electrons passing along a chain of electron carriers-e transport chain
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What coenzyme takes up the hydrogens released during the Krebs cycle?
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What coenzyme takes up most of the hydrogens released during respiration?
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What reactions occur as the electrons pass along the electron transport chain?
REDOX REACTIONS- the carrier is reduced when it receives the electrons and is oxidised when it passes them on
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What happens to the protons in the electron transport chain?
The protons (H+) move across the inner mitochondrial membrane creating high H+ concentrations in the intermembrane space. H+ diffuses back into the mitochondrial matrix down the electrochem gradient.H+ diffusion allows ATPase to catalyse ATP synth
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How does water form at the end of the electron transport chain?
Electrons and H+ ions recombine to form hydrogen which then combine to create water. If the supply of oxygen stops, the electron transport chain and ATP synthesis also stops
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Describe chemiosmosis
Energy released as e- pass along transport chain,this energy used to move H+ from matrix to intermem space.Creating elec-chem gradient(intermem space>+ than matrix).H+ diffuse down through protein channels.ATP synthesis catalysed by ATPase on protein
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What happens to the H+ in the matrix?
The H+ and electons recombine to form hydrogen atoms. These combine with oxygen to form water. The oxygen acting as the final carrier in the electron transport chain is thus reduced
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Why is the synthesis of ATP through the electron transport chain called oxidative phosphorylation?
Reduction and oxidation reactions occur as the the electrons pass along the electron transport chain
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What is substrate level phosphorylation?
The energy for the formation of ATP comes from the substrates
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What is the role of a carrier in the electron transport chain?
Electrons pass from one carrier to the next in a series of redox reactions. As this is happening energy is released. The energy released is used to pump H+ into the intermembrane space
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How much ATP is produced during aerobic respiration?
The maximum number of ATP molecules from one glucose molecule is 38
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How is the rate of aerobic respiration measured in small organisms?
By using a respirometer to measure the uptake of oxygen. AS the living organisms in the experiment tube take up oxygen, the fluid in the manometer will move in the direction of the organism. Potassium hydroxide solution absorbs any CO2 produced
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What is the advantage of having a system of enzyme-controlled reactions to transfer energy from food fuels?
Prevents the cell overheating and allows the controlled release of energy in small useful quantities
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What happens to pyruvate during anaerobic respiration?
It is reduced into lactate and oxidised NAD is regenerated
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How is lactate removed?
After anaerobic respiration most of the lactate is converted back into pyruvate. It is oxidised directly to CO2 and H2O by the Krebs cycle,energy released to synth ATP. As a result oxygen uptake is greater than normal in the recovery period- oxy debt
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What are the effects of lactate build up?
H+ accumulate from the lactic acid in the cytoplasm,they neutralise the negatively charged groups in the active site of the enzyme.Attraction between charged groups in active site and enzyme affected-sub may no longer bind
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Why are athletes in training advised not to simply stop of lie down after strenuous exercise, but rather to aim for active recovery through gentle exercise?
To maintain rapid blood flow through the muscles to supply oxygen and remove lactate
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How is the immediate regeneration of ATP achieved?
Using Creatine Phosphate
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What is Creatine Phosphate?
A substance stored in muscles that can be hydrolysed to release energy. This energy can be used to regenerate ATP from ADP and phosphate, the phosphate is provided by creatine itself. Creatine is broken down as soon as exercise starts
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When are creatine stores regenerated?
Regenerated from ATP when the body is at rest
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What are the three energy systems
ATP/PC, aerobic respiration and anaerobic respiration
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What is aerobic capacity?
The ability to take in, transport and use oxygen
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What is cardiac output?
The volume of blood pumped by the heart in a minute
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How is adequate oxygen supply maintained when running?
1.Increasing cardiac output 2.faster rate of breathing 3.Deeper breathing
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What does cardiac output depend on?
The stroke volume and the heart rate cardiac output=stroke volume x heart rate
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What is stroke volume?
The volume of blood pumped of the left ventricle each time the ventricle contracts (measured in cm3)
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What is venous return?
The rate of blood flow back to the heart
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What factors cause differences in our resting heart rate?
Difference in heart size as a result of body size and genetic factors and endurance training
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Why does stroke volume increase during exercise?
When the body is at rest the ventricles do not completely empty with each beat approx 40% of the blood remains in the ventricles after contraction.During exercise stronger contractions occur, ejecting more of the residual blood from the heart
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What is heart rate?
The number of heart beats per minute
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Why does stroke volume and cardiac output increase with exercise?
In diastole,during exercise the heart fills with a larger volume of blood. The heart muscle is stretched to a greater extent, causing it to contract with a greater force so more blood is expelled
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What is the name of the artery that is found in our wrist?
Radial artery
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What is the name of the artery that is passing through our neck?
carotid artery
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What is the average heart rate for males, females and an average fit person?
Male-70bpm Females-72bpm Fit person-65bpm
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Why would a larger heart have a lower resting heart rate?
It will expel more blood with each beet and so does not need to beat as frequently to circulate the same volume of blood around the body
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What effect does endurance training have on the heart?
Increases the size of the heart by thickening the heart muscle walls
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What proof is there that the heart muscle is myogenic?
The heart can beat without any input from the nervous system
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Where does depolarisation start?
SAN (sinoatrial node)
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What is the SAN and where is it located?
Small area of specialised muscle fibres located in the wall of the right atrium.
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What causes the atria to contract
The SAN generates an electrical impulse which spreads across the left and right atria causing them to contract at the same time
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What causes the ventricles to contract?
Impulse produced by SAN travels to AVN, from here the impulse is conducted to the ventricles causing them to contract after a delay of 0.1s.
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What is the AVN?
Specialised cells
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Why is there a delay between the impulse reaching the ventricles from A?VN
Ensures the ventricles have finished contracting, so the ventricles have filled with blood before they contract
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What are the Purkyne fibres?
Large, specialised muscle fibres that conduct impulses to the apax. The right and left bundles of fibres are collectively called the bundle of His
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Why does contraction of the ventricles begin at the apex?
The first ventricular cells to be depolarised are at the apex of the heart, so the contraction begins at this point and continues upwards towards the atria.Producing wave of contraction up ventricles pushing blood into the aorta and pulmonary artery
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What does an ECG (electrocardiogram) do?
Displays and detects the electrical activity of the heart
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What is an ECG
A graphic record of the electrical activity during the cardiac cycle
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How is an ECG carried out?
Electrodes are attached to the person's chest and limbs to record electrical currents produced during the cardiac cycle.When there is change in polarisation of cardiac muscle small electrical currents detected on skin's surface this is what ECG measu
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What does the P wave show us in an ECG?
Depolarisation of the atria, leading the atrial systole
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What does the PR interval show us in an ECG?
The time taken for impulses to be conducted from the SAN across the atria to the ventricles through the AVN
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What does the QRS complex in an ECG show us?
The wave of depolarisation resulting in ventricular systole
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What does the T wave show us in an ECG?
Repolarisation (recovery) of the ventricles during diastole
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Why does an ECG not show atrial repolarisation?
Because the signals generated are small, and are hidden by the QRS complex
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What is bradycardia?
A heart rate of less than 60bpm
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What are some of the possible causes of bradycardia?
Hypothermia, heart disease or use of medicines or drugs. However can also be a symptom for heart problems
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What is tachycardia?
A heart rate greater that 100 bpm
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What are some of the possible causes of tachycardia?
Anxiety, fear, fever or exercise. However it can also be a symptom coronary heart disease, heart failure, use of medicines or drugs or anaemia
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What happens during a period of ischaemia?
Heart muscle does not receive blood due to atherosclerosis causing a blockage of the coronary arteries.The normal electrical activity and rhythm of the heart are disrupted and arrhythmias can affect a larger area of the heart muscle
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What information can an ECG trace provide us with?
Abnormal heart beats, areas of damage and inadequate blood flow
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What is your heart rate controlled by?
The cardiovascular control centre located in the medulla of the brain
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What is the autonomic nervous system?
The nervous system that you have no control over
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Where do the nerves forming part of the autonomic nervous system lead to?
Lead from the cardiovascular control centre to the heart
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Name the two nerves that make up the autonomic nervous system
Sympathetic nerve and vagus nerve
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What does the cardiovascular control centre detect?
Accumulation of carbon dioxide and lactate in the blood, reduction of oxygen and increased temperature
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What happens when the SAN is stimulated by the sympathetic nerve?
Causes an increased heart rate
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What happens when the SAN is stimulated by the vagus nerve?
Causes heart rate to decrease
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What happens to blood pressure as cardiac output increases?
Rises.To prevent it from rising too far, pressure receptors in the aorta and in the carotid artery send impulses back to the CV control centre.Inhibitory nerve impulses sent to SAN. Negative feedback prevents further rise in heart rate
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What does stimulation of the sympathetic nerve do?
Prepares the body's systems for action (for the fight of flight response)
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What do stimulation of the parasympathetic nerve do?
Controls the body's systems when resting and digesting
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What effects does stimulation of the sympathetic nerve have?
Increases breathing rate, increases heart rate and stroke volume and inhibits peristalsis (muscle contractions in the gut wall that move food through the gut)
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What effects does the stimulation of the parasympathetic nerve have?
Decreases breathing rate, decreases heart rate and stroke volume and stimulates peristalsis (muscle contractions in the gut wall that move food through the gut)
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What causes the release of the hormone adrenaline?
Fear, shock and excitment
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Where is adrenaline released from into the blood stream?
The adrenal glands located above the kidneys
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What effects does adrenaline have?
Has a direct affect on the SAN,increasing heart rate to prepare body for any likely physical demands.Causes dilation of arterioles supplying skeletal muscles and constriction of arterioles going to digestive system and other non-essential organs.
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Why does pressing on your carotid artery reduce pulse rate, thereby giving a false reading?
Pressing on your neck causes an increased blood pressure in the carotid artery. Blood pressure receptors in the carotid artery would signal to the CV control centre which in turn would stimulate the vagus nerve resulting in a reduced heart rate
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Where can a reliable pulse be taken?
The wrist of the groin
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What is tidal volume?
The volume of air we breath in and out at each breath
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What happens when exercise begins?
We increase our breathing rate and depth of breathing
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What is vital capacity?
The maximum volume of air we can inhale and exhale
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What type of people have higher vital capacity?
Fit people, singers and people playing wind instuments
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What can be measured using a spirometer?
Lung volumes including tidal volume and vital capacity
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What is minute ventilation?
The volume of air taken into the lungs in one minute
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How is minute ventilation calculated?
minute ventilation=tidal volume x breathing rate
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What controls breathing?
The ventilation centre in the medulla oblongata
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What happens during inhilation?
Ventilation centre sends nerve impulse every 2-3 seconds to the external intercostal muscles and diaphragm muscles.These muscles both contact causing inhalation.
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What happens during deep inhalation?
External intercostal and diaphragm muscles contract as well as the neck and upper chest muscles contracting
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How is inhalation stopped?
As the lungs inflate,stretch receptors in the bronchioles are stimulated. The stretch receptors send inhibitory impulses back to the ventilation centre. As a result impulses to the muscles stop and the muscles relax
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What happens during exhalation?
Caused by the elastic recoil of the the lungs and by gravity helping to lower the ribs.Not all the air in the lungs is exhaled with each breath.The residual mixes with the air inhaled with each breath
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When do the internal intercostal muscles contract?
During deep exhalation e.g. during vigorous exercise a large volume of air is exhaled , leaving less residual air in the lungs
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What are the most important stimulus controlling breathing rate and depth of breathing at rest?
Concentration of dissolved carbon dioxide in arterial blood,via its effect on pH
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How does a small increase in blood carbon dioxide concentration cause a large increase in
CO2 dissolves in blood plasma,carbonic acid formed.Carbonic acid dissociates into H+ and HCO3-,causing pH of blood to become more acidic.Chemoreceptors found in VC are sensitive to H, detect rise in H+.Impulses sent from VC-breathing stimulated
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What are chemoreceptors in the walls of the carotid artery and aorta stimulated by?
Changes in pH resulting from changes in carbon dioxide concentration. They monitor the blood before it reaches the brain and send impulses to the ventilation centre
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What is the role of the motor cortex?
Region of the brain that controls movement
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What does the motor cortex do once exercise begins?
Sends impulses to the ventilation centre causing ventilation to increase sharply
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During vigorous exercise the concentration of oxygen in the lungs is higher than when at rest.Suggest the reason for this elevated oxygen level and the advantage of it.
The depth and rate of breathing increases so there is a greater volume of air inhaled and mixed with the residual air in the lungs-conc. of O2 increases-steeper diffusion gradient-increased speed of gas exchange-advantage is raised metabolic rate
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Suggest why it is beneficial that stimulation of stretch receptors in the muscles increases ventilation
Stretch receptors signal the start of movement, allowing ventilation to increase before there is a build-up of the waste products of respiration
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What is aerobic capacity dependent on?
Uptake and transport of oxygen to the muscles as well as the efficiency of use once it reaches the muscle fibres
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What are slow twitch fibres?
Fibres that are specialised for slower, sustained contractions and can cope with long periods of exerciseThey need to carry out large amounts of aerobic respiration to do this
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What are the key features of slow twitch fibres?
1.Large amount of myoglobin 2.Many mitochondria 3.Many capillaries ensuring good oxygen supply 4. Aerobic respiration 5.Low glycogen content 6.Stores energy as triglyceride
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What are fast twitch fibres?
Fibres specialised to produce rapid, intense contractions.The ATP used in these contractions is produced almost entirely from anaerobic glycolysis
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What are the key features of fast twitch fibres?
1.Low levels of myoglobin 2.Little amount of mitochondria 3.Stores energy as ATP 4.Has high glycogen content 5.Few capillaries 6.Fatigue quickly due to lactate build up
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What is myoglobin and what does it do?
It is a protein similar to haemoglobin. It has a high affinity for oxygen, and only releases it when the concentration of oxygen in the cell falls very low ; it therefore acts as an oxygen store within muscle cells
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What will happen to metabolic reactions if body temperature falls below or rises above the normal rage?
Low temperatures lead to low metabolic rates as enzyme controlled reactions are slow;high temperatures increase the rate of metabolic reactions initially, but then it declines as enzymes denature at higher temperatures
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What is homeostasis?
The maintenance of a stable internal enviroment
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What is negative feedback?
When deviation from the norm results in a change in the opposite direction back to the norm
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How is temperature maintained in humans?
By negative feedback
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What is the hypothalamus?
A control mechanism that acts as a thermostat, turning on the effectors necessary to return the temperature to the norm
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How does the hypothalamus cause heat loss?
STIMULATES:sweat glands to secrete sweat INHIBITS:contraction of arterioles in skin, hair erector muscles , liver(reduces metabolic rate),skeletal muscles(no shivering)
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How does the hypothalamus cause heat gain?
STIMULATES:Arterioles in skin constrict(decreased diameter so decrease in blood flow), hair erector muscles contract, liver to raise metabolic rate,skeletal muscles INHIBITS:Sweat glands
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What effectors are activated when the body temperature falls below the norm?
Hair erector muscles, muscles in the walls of the arterioles in the skin, skeletal muscles and liver cells
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How is energy lost increased by vasodilation?
Shunt vessels constrict and muscles in the walls of the arterioles relax.Blood flows through the arterioles making them dilate.Blood flows closer to the surface so more energy is lost
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How is energy loss decreased by vasoconstriction?
Muscles in the arteriole walls contract causing the arterioles to constrict, reducing the blood supply to the surface capillaries.Blood is diverted through the shunt vessel which dilates as more blood flows through.Blood further from skin surface.
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What are the four methods of energy transfer?
Radiation,conduction,convection and evaporation
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Why does humidity make marathon running more dangerous?
Less energy is lost by evaporation so it is harder for athletes to keep their body temperatures down to a safe level
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What are URTIs
Upper Respiratory Tract Infections
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How does moderate exercise effect the immune system?
Increases the number and activity of natural killer cells which are found in the blood and lymph and provide non-specific immunity against cells invaded by viruses and cancerous cells
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How are natural killer cells activated?
Activated in several ways such as cytokines and interfron
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How does vigorous exercise effect the immune system?
The activity of cells such as natural killer cells,phagocytes,B cell and T helper cells decreases.As a result of this the immune system is depressed
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How will the action of killer T cells be affected by the decrease in T helper numbers
Fewer cytokines produced and so T killer cell will not be activated by cytokines
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What are the disadvantages of exercising too much?
More prone to infection as there is a reduction in immunity and the wear and tear of joints
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What are the disadvantages of exercising too little?
Increased risk of obesity, higher risk of developing coronary heart disease and more likely to develop diabetes
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What joint is particularly susceptible to wear and tear injuries?
The knees
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What happens when the articular cartilage covering the surface of the bones wears away?
The bones are able to grind on each other, causing damage that can lead to inflammation and a form of arthritis
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When does Patellar tendonitis (jumper's knee) occur?
When the kneecap doesn't glide smoothly across the femur due to damage of the articular cartilage on the femur
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What is bursae?
Fluid sacs that cushion the points of contact between between bones,tendons and ligaments
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What happens if the bursae swells up with extra fluid?
Can push against other tissues in the joint, causing inflammation and tenderness
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What does sudden twisting or abrupt movements of the knee joint result in?
Damage to the ligaments?
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What are the problems with making large incisions during surgery?
Great deal of bleeding, a lot of pain, increased risk of infection and prolonged recovery after the operation
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What is the name of keyhole surgery performed on joints?
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How is an arthroscopic procedure carried out?
Two small incisions made. A small camera and light source are inserted, allowing the inside of the joint to be seen and a diagnosis to be made and confirmed.if required miniature instruments are inserted.
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What damage of the knee joint can be tackled effectively by keyhole surgery?
Damage to the cruciate ligament
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What type of joint is the knee and how many ligaments is it held together by?
Hinge joint and it is joined together by four ligaments
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What is the role of the posterior and anterior cruciate ligament?
Posterior cruciate ligament prevents the knee from being bent too far back whilst anterior cruciate ligament prevents the knee from being bent too fare forwards
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What is prosthesis?
An artificial body part used by someone with a disability to enable him/her to regain some degree of normal function or appearance
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What are some of the successful uses of prosthetics?
Replacing hip and knee joints with artificial joints
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How is a knee joint replaced?
Incisions made in affected knee.Once patella (kneecap) is moved out of the way,ends of femur and tibia trimmed to fit prosthesis.Underneath of the patella also trimmed to fit artificial piece.Bone cement used to attach new surfaces
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What are the advantages of exercise?
Increases arterial vasodilation lowering b.p.,healthy weight maintained, reduces risk of diabetes
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What are hormones?
Chemical messengers, released directly into the blood from endocrine glands.
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Why are many hormones produced in their inactive form or packaged in secretory vesicles by the golgi apparatus?
So that the cells in the endocrine glands that make the hormone are not themselves affected by their products
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What hormones are produced by the pituitary gland?
Growth hormone(stimulates growth),follicle-stimulating hormone(controls testes and ovaries) and antidiuretic hormone(causes re-absorption of water in kidneys
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What hormone is produced by the thyroid gland?
Thyroxine (raises basal metabolic rate)
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What hormone is produced by the adrenal gland?
Adrenaline (raises basal metabolic rate, dilates blood vessels and prepares the body for action)
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What hormone is produced by the pancreas?
Insulin (lowers blood glucose concentration)
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What hormone is produced by the ovaries?
Oestrogen (promotes development of ovaries and female secondary sexual characteristics)
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What hormone is produces by the testis
Testosterone (Promotes development of male secondary sexual characteristics)
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Why can steroid hormones pass through the cell membrane?
They are lipid based so dissolve
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Most hormones travel all around the body in the blood, and will come into contact with many cells.Why do hormones only produce a response within cells of their target organs?
In order for the hormone to produce a response it have to bind to a complimentary receptor.Only the target cells have the complementary receptors
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What is EPO?
Stands for Erythropoietin which is a peptide hormone produced naturally by the kidneys. It stimulates the formation of new red blood cells in the bone marrow
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Explain how taking EPO would increase the performance of an endurance athlete
Would increase the number of red blood cells and hence the amount of haemoglobin;improving the blood's oxygen carrying capacity;more oxygen delivered to the muscle tissue and hence improving aerobic capacity
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What are some of the health risks associated with EPO?
If EPO levels are too high the body will produce too many red blood cells, which can increase the risk of thrombosis ,possibly leading to heart attack or stroke. EPO injections also been implicated in the deaths of several athletes
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What is testosterone?
A steroid hormone (made from cholesterol) produced in the testes and adrenal glands.Causes the development of the male sex organs
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What does testosterone do?
Binds to androgen receptors on target cells. They modify gene expression to alter the development of the cells e.g. they increase the anabolic reactions such as protein synthesis in muscle cells, increasing the size and strength of muscle
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What are some of the negative effects of using anabolic steroids?
Cause high blood pressure, liver damage, kidney failure and heart disease
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Name a performance enhancing drug that is not banned
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Where is creatine found?
In meat and fish however it is also synthesised in the body from the amino acids glycine and arginine
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Why is creatine considered to be performance-enhancing?
Increases the amount of creatine phosphate in muscles; this would improve performance in short-duration, repeated, high intensity exercise
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What are some negative effects of taking creatine?
Diarrhoea, nausea, vomiting, high blood pressure, kidney damage and muscle cramps
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Arguments for performance enhancing drugs
1. Athletes should have the right to decide whether to take the drug or not 2. Already inequality of competition (more training or resources)
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Arguments against performance enhancing drugs
1.Unhealthy 2.Unfair competition 3.Those taking the drugs may not understand the possible health consequences 4.Pressurised by others
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