Role of the Skeleton
- Protects vital organs
- Support and structure
- Allows movement and softer tissues to work against it (e.g. muscles)
- Blood production- bone marrow (rbc/ wbc/ platelets)
- Calcium store
- Phosphorous store
The skeleton consists of:
Lack of exercise causes bones to lose density and strength. Age also makes bones lose density and strength. Weight bearing exercises (e.g. jogging) increases density and strength. The skeleton changes throughout life. Fish amphibians, reptiles, birds and mammals are all vertebrates ( they all have a backbone and internal skeleton).
Bones, muscles, tendons and ligaments all work together to allow movement.
- Bones- Rigid tissues, support weight without bending.
- Muscles- Tissue, contracts and relaxes to cause movement.
- Tendons- Strong, fibrou, flexible, connective tissue, joins muscles to bone.
- Ligaments- Strong, fibrous, elastic connective tissue, connects bones in a joint.
Muscles can only cause bones to move by contracting, so they only move in one direction, so they work in antagonist pairs (one contracts whilst the other relaxes).
E.g. lower arm moves upward: Bicep contracts, tricep relaxes. It is moved down again when: tricep contracts, bicep relaxes.
How joints work?
Adapted to allow smooth movement and resist wear and tear.
- Cartilage- smooth, prevents bones from rubbing together and reduces friction.
- Synovial fluid- Helps to lubricate joint, reduces friction.
- Ligaments- (elastic), help to stabilise joint during movement.
- Tendons- transmit the forces from contracting muscles to the bones near the joint.
Joints allow movement and flexibility. There are two types: ball and socket e.g. hip and hinge e.g. knee.
Ball and socket- Dislocation possibility, circular movement, range of motion, biggest joints.
Hinges- One direction, less range of motion, more likely to tear ligaments than dislocate.
- Bones at joint held together by ligaments.
- Ends of bones covered by a smooth layer of cartilage to reduce friction. Cartilage can be slightly compressed to act as a shock absorber .
- Membranes at some joints release oily synovial fluid to lubricatethe joints allowing them to move more easily, by reducing friction.
Exercise programs can be used to lose weight, improve cardiovascular fitness, increase strength, recover from injury or surgery.
- Current symptoms
- Current medication
- Alcohol and tobacco consumption
- Current level of physical activity
- Family medical history
- previous history
All exercise programs carry some risks.
- Blood pressure
- BMI ( body mass(kg)/ [height(m)]2
- Heart rate
- Fat percentage
- Recovery time
- Baseline data
- Most common sporting injury
- Happens when ligaments are overstretched, usually by twisting their ankle or knee.
- Redness and swelling
- Surface bruising
- Difficulty walking
- Dull, throbbing ache or sharp cramping pain
The usual treatment for sprains is RICE
Red blood cells- most common
Travels suspended in blood plasma,
Bicocave shape- shaped like a flat disc with a dimple on each side, to increase surface area for exchanging oxygen.
No nucleus to create more space inside so they can be packed full of haemoglobin.
Role- to carry oxygen in the blood. They take up oxygen in the lungs and deliver it to cells in the bodies tissues.
Contain haemoglobin- Substance combines with oxygen to form oxyhaemoglobin. In body cells oxyhamoglobin breaks down to haemoglobin, releasing oxygen from the red blood cell.
White blood cells
Defend against infection from microorganisms.
Phagocytes- kill microorganisms, surrounding and engulfing them, once inside they are digested and killed by powerful enzymes.
Lymphocytes- produce antibodies, which stick onto foreign bodies, killing them or making them stick together, making it easier for phagocytes. Theyalso neutralise the toxins released by antibodies.
Platelets and plasma
Platelets- Small fragments of cells, no nucleus.
Help blood to clot in wounds. When blood vessel walls are damaged platelets seal and clot the wound. Preventing the loss of blood cells and stopping microorganisms entering the bloood through the wound.
Plasma- carries all the cells contained in blood- carrie glucose, amino acids, antibodies,hormones and waste.
Straw coloured liquid.
co2 produced as waste product by cells in body tissues. This co2 is dissolved in blood plasma, transported to the lungs and removed from the body. Glucose is also carried to body tissues by being dissolved in blood plasma.
Arteries- Thick layer of muscles and elastic fibres. Take blood from heart to body. Thick outer walls to withstand high pressure generated by the heart.
Veins- Thin layer of muscleand elastic fibres, valves stop the blood flowing backwards. Bring blood tothe heart. Thin layer of muscle and elastic fibres allow vein to be squashed when you move. Pushes blood back to heart.
Capillaries- 1 cell thick- allows diffusion of oxygen and food to cells and waste out of cells. Take blood to and from tissues.
Double circulatory system
- Humans have a double circulatory system- 2 circuits joined together.
- The first pumps deoxygenated blood to the lungs to take in oxygen. The blood then returns to the heart.
- The second pumps the oxygenated blood around the body. The blood gives up its oxygen at body cells and the deoxygenated blood returns to the heart, to be pumped again.
- The right atrium of the heart recieves deoxygenated blood from the body through the wena cava.
- The deoxygenated blood moves through to the right ventricle, which pumps it to the lungs via the pulmonary artery.
- The left atrium recieves oxygenated blood from the lungs through the pulmonary vein.
- The oxygenated blood then moves through to the left ventricle, which pumps it around the body via the aorta.
The valves in the heart prevent the backflow of blood- veins also have valves for this reason.
There are two coronary arteries which supply the heart muscle with blood.
The left ventricle wall is thicker than the right as it has to pump blood all around the body. The atria have even thinner walls because they only pump to the ventricles.
- Arteries branch into capillaries, which are really tiny blood vessels.
- They have permeable walls to allow diffusion of substances out.
- Natworks of capillaries in tissue are called capillary beds.
- As blood passes through the beds small molecules (e.g. water, glucose and oxygen) to form the tissue fluid which surrounds the cells. The substances diffuse out of the tissue fluid into the cells.
- Waste chemicals e.g. carbon dioxide and urea diffuse out of the cells into the tissue fluid, then into the capillaries.
- The tissue fluid allows cells to get the substances they need and to get rid of waste with out a capillary supplying every single cell.
- Bones are attached to muscles by tendons
- Muscles move bones at a joint by contracting
- Tendons cant stretch so when a muscle contracts a muscle pulls on the bone, transmitting the force from the muscle to the bone.
- Muscles can only pull on bones to move a joint- they cant push. This is why they come in antagonistic pairs.
- Exercise helps to increase fitness
- Being fit is a measure of how well you can do physical activities.
- Exercise increases fitness, and it's most effective when it's done in a structured way by following a regime. Fitness practitioners, e.g. personal trainers and gym instructors can design fitness regimes for people.
- When you are not exercising your heart rate and blood pressure are said to be at resting levels.
- During exercise your blood pressure and heart rate increase.
- When you stop exercising your blood pressure and heart rate return to their resting levels. The time this takes to happen is the recovery period.
- The fitter you are the shorter your recovery time.
Excessive exercise can cause injuries:
- Sprains- damage to a ligament,usually by being stretched too much.
- Dislocations- a bone comes out of its socket.
- Torn ligaments- the ligament tears.
- Torn tendons- a tear in the tendon that attaches the muscle to its bone.It happens when a muscle contracts in one direction, but is pulled in the other.
Physiotherapists treat skeletal- muscular injuries. They may give treatment to reduce pain and swelling (e.g. RICE, cortisone injections) and therapies (e.g. laser treatment) to speed up healing.
They give advise on the best exercises to do to rehabilitate after an injury. These may include graded exercises, which steadily build up the strength of a muscle or joint.
Keeping body temperature
- The body must balance the amount of heat gained (e.g. through respiration) and the heat lost to keep the core body temperature constant.
- Temperature recepters in the skin detect the external temperature, and recepters in the hypothalamus (part of the brain) detect the temperatur of the blood.
- The nervous system helps to control body temperature, using the following negative feedback mechanism:
- Temperature recepters detect that core body temperature is too high or low.
- The hypothalamus acts as a processing centre- it recieves information from the themperature recepters and triggers the effector automatically.
- Effectors e.g. sweat glands or muscles produce a response and counteract the change.
Some receptors work antagonistically e.g. one effector heats and another cools- they will work at the same time to produce a steady temperature. This allows a more sensitive response.
Altering body temperature
- Blood vessels clod to the skins surface get bigger in diameter- this is called vasodilation. As a result more blood gets to the surface of the skin, and loses some of its heat to the surroundings.
- Sweat glands produce more sweat- when water in sweat evaporates heat is used, which cools the bosy. If you sweat alot e.g. during exercise the water loss may cause dehydration. If you are dehydrated your body will produce less sweat and your body temperature will rise.
- Blood vessels close to the skins surface get smaller in diameter- this is called vasoconstriction. This means less blood gets to the surface of the skin, which stops the blood losing as much heat to the surroundings.
- You shiver- your muscles contract rapidly. This increases the rate of respiration and warms the tissue surrounding the muscles.
Controlling blood sugar
Insulin controls blood sugar level
- Eating sugary foods causes blood sugar to rise rapidly.
- This is because simple sugars and digested and absorbed into the blood really quickly.
- Blood sugar levels need to be kept steady- the body uses insulin to control it.
- When blood sugar levels get too high, the pancreas releases insulin, which causes sugar to be removed from the blood.
Diabetes is where blood sugar can't be controlled properly. There are two types.
- The pancres stops producing insulin.
- This means blood sugar level can rise to a dangerous level.
- It is controlled by injecting insulin into the blood at mealtimes.. The injection must have the right amount to make sure the body doesn't remove too much sugar.
- Late onset- usually develops in later life. Having a poor diet or being obese increasing the rick of developing type 2 diabetes.
- The body no longer responds to its own insulin, or it doesnt make enough. This causes blood sugar to rise to a dangerous level.
- It can be controlled by exercising and eating a carefully controlled diet.
- They can control their blood sugar level by eating foods that are high in fibre and complex carbs. They are digested slower than simple sugars, so the sugar is absorbed into the blood over a longer period of time.
- This means blood sugar level rises more slowly and the body can remove the sugar (e.g. by respiration) before it becomes too high.