1.1b Cardiovascular and Respiratory Systems

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  • Created by: kwalker23
  • Created on: 07-01-21 12:29
Pulmonary circuit
Circulation of blood through the pulmonary arteries to the lungs and pulmonary veins back to the heart
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Systemic circuit
Circulation of blood through the aorta to the body and vena cava back to the heart
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Oxygenated blood
Blood saturated with oxygen and nutrients, such as glucose
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The Conduction system
1. SA node - Generates electrical impulse, causing atria walls to contract. Determines HR
2. AV node - Collects impulse, delays it by 0.1s to allow atria to finish contracting
3. Bundle of His - Located in septum, splits impulse in two, ready to be distri
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Myogenic
Capacity of the heart to generate its own electrical impulse, causes cardiac muscle to contract
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Conduction system - Definition
Set of structures in the cardiac muscle which create and transmit an electrical impulse forcing atria and ventricles to contract
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Cardiac cycle - Diastole (Relaxation)
Relaxation of atria and ventricles means lower pressure within the heart
Blood then passively flows through the atria and into ventricles
AV valves are open, allowing blood to move freely from the atria to the ventricles
Semilunar valves are closed at thi
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Cardiac cycle - Systole (Contraction)
Atrial systole - Atria contract, forcing blood into the ventricles
Ventricular systole - Ventricles contract
AV valves close
Semilunar valves open
Blood is pushed out of the ventricles and into the large arteries leaving the heart
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Heart Rate (HR)
The number of times the heart beats per minute.

Typical resting average - 72bpm
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Stroke Volume (SV)
The amount of blood ejected from the left ventricle per beat

Typical resting average - 70 ml
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Cardiac Output (CO)
The amount of blood ejected from the left ventricle per minute. HR*SV = CO

Typical resting average - 5l/min
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Bradycardia
Resting heart rate below 60bpm
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Maximum heart rate
Calculated by subtracting your age from 220
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Heart Rate response to exercise
HR increases proportional to intensity to exercise until we reach HR max
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Stroke Volume response to exercise
SV increases in proportion to exercise intensity until a plateau is reached at approximately 40-60% of working capacity.
SV is able to increase due to: Increased venous return, and the Frank-Starling mechanism
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Cardiac Output response to exercise
CO increases in line with exercise intensity and plateaus during maximal exercise.
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Venous Return
Return of blood to the right atria through the veins
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Frank-Starling mechanism
Increased venous return leads to increased SV, due to increased stretch of ventricular walls and therefore force of contraction
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HR, SV and CO during recovery
SV is maintained during early stages of recovery, as HR rapidly reduces. This will maintain blood flow and the removal of waste products while lowering the stress and workload of the cardiac muscle
CO; in recovery, there is a rapid decrease followed by a
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Regulation of HR during exercise
When the HR needs to increase or decrease the brain gets involved. Known as cardiac control.
The cardiac control centre (CCC) is: Controlled by automatic nervous system and determines firing of SA node
Located in medulla oblongata
Responsible for regulat
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Three factors controlling activity of CCC - Neural Control
Proprioceptors - In muscles, tendons and joints, these inform CCC movement has increased

Chemoreceptors - In aorta and carotid arteries, detect a decrease in blood pH due to increase in lactic acid and CO2

Baroreceptors - In blood vessel walls, inform t
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Three factors controlling activity of CCC - Intrinsic Control
Temperature - Changes will affect blood viscosity and speed of nerve impulse transmission

Venous Return - Changes will affect the stretch in ventricle walls, force of contraction and therefore SV
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Three factors controlling activity of CCC - Hormonal Control
Adrenaline and noradrenaline - These are released from the adrenal glands and increase SV and HR
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Blood Vessels - Arteries and arterioles
Carry oxygenated blood from heart to muscles and organs
Contain blood under high pressure
Have large layer of smooth muscle and elastic tissue
Smooth muscle can vasodilate and constrict, regulating blood flow and pressure
Ring of smooth muscle surroundin
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Blood Vessels - Capillaries
Walls are once cell thick
This is where gas exchange takes place. Oxygen passes through capillary wall and into tissues; CO2 passes from tissues into blood through capillary wall
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Blood Vessels - Veins and Venules
Carry deoxygenated blood from muscles and organs back to heart. Have thin walls.
Have small layer of smooth muscle allowing them to venoconstrict and dilate.
Contain blood under low pressure.
Have one-way pocket valves preventing back flow of blood agains
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Venous return mechanisms
Pocket Valves - Located in veins and prevent backflow of blood
Smooth muscle - Push blood back towards heart through venoconstriction
Gravity - Blood above the heart returns
Muscle pump - Veins between skeletal muscles are squeezed, pushing blood back to
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Vasodilation and vasoconstriction
Vasodilation: Widening of arteries, arterioles and pre-capillary sphincters
Vasoconstriction: Narrowing of arteries, arterioles and pre-capillary sphincters
Venodilation: Widening of veins and venules
Venoconstriction - Narrowing of veins and venules
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Venodilation and venoconstriction
Venodilation: Widening of veins and venules
Venoconstriction - Narrowing of veins and venules
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Vascular shunt mechanism - At rest
Arterioles to organs vasodilate, increasing blood flow; arterioles to muscle vasoconstrict to limit blood flow
Pre-capillary sphincters vasodilate, opening up capillary beds to allow more blood flow to the organ cells; pre-capillary sphincters of capillar
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Vascular shunt mechanism - During exercise
Arterioles to organs vasoconstrict, decreasing blood flow; arterioles to muscles vasodilate to increase blood flow
Pre-capillary sphincters vasoconstrict, closing up the capillary beds to decrease blood flow to the organ cells; pre-capillary sphincters of
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Vasomotor control
Vasomotor control centre (VCC) is located in medulla oblongata
Smooth muscle in muscle of walls of arterial blood vessels is always in a state of constriction
VCC alters level of stimulation sent to arterioles and pre-capillary sphincters at different sit
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Breathing rate (f)
Number of inspirations or expirations per minute
Resting value (untrained) - 12-15 breaths/min
Maximal value (untrained) - 40-50 breaths/min
Resting value (trained) - 11-12 breaths/min
Maximal value (trained) - 50-60 breaths/min
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Tidal volume (TV)
Volume of air inspired or expired per breath
Resting value (untrained) - 500ml
Maximal value (trained) - 2.5-3l
Maximal value (untrained) - 500ml
Resting value (trained) - 3-3.5l
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Minute ventilation (VE)
Volume of air inspired or expired per minute. TV*f = VE (tidal volume*breathing rate = minute ventilation
Resting value (untrained) - 6-7.5l/min
Maximal value (untrained) - 100-150l/min
Resting value (trained) - 5.5-6l/min
Maximal value (trained) - 160-21
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Mechanisms of breathing - Inspiration during exercise: Active process
In addition to external intercostal muscles and diaphragm: Sternocleidomastoid lifts sternum and scalene and pectoralis minor contract and lift ribs more
Effect - volume of thoracic cavity increases, creates larger concentration gradient in lungs, therefo
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Mechanisms of breathing - Expiration during exercise: Active process
In addition to external internal intercostal muscles and diaphragm: internal intercostal muscles contract and pull the ribs in and down and the rectus abdominals contracts and pushes the diaphragm up.
Effect - Decrease in volume of thoracic cavity increa
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Mechanics of breathing - Inspiration at rest: Active process
External intercostal muscles between ribs contract, pulling the chest walls up and out.
The diaphragm muscle below the lungs contract and flattens, increasing the size of the best
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Mechanics of breathing - Expiration at rest: Passive process
External intercostal muscles between ribs relax so that the chest walls move in and down.
The diaphragm muscle below the lungs relaxes and bulges up, reducing the size of the chest.
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Respiratory regulation at rest
The IC is responsible for rhythmic cycle of breathing. Nerve impulses are generated and stimulate the inspiratory muscles, causing them to contract, via the: intercostal nerve to the external intercostal, phrenic nerve to the diaphragm.
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Respiratory regulation during exercise
Chemical control: Chemoreceptors - Located in aorta and carotid arteries, detect changes in blood acidity, increases in CO2 and decreases in O2.
Neural control - Thermoreceptors - Inform increases in blood temp
Proprioceptors - Inform of motor activity
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Other cards in this set

Card 2

Front

Circulation of blood through the aorta to the body and vena cava back to the heart

Back

Systemic circuit

Card 3

Front

Blood saturated with oxygen and nutrients, such as glucose

Back

Preview of the back of card 3

Card 4

Front

1. SA node - Generates electrical impulse, causing atria walls to contract. Determines HR
2. AV node - Collects impulse, delays it by 0.1s to allow atria to finish contracting
3. Bundle of His - Located in septum, splits impulse in two, ready to be distri

Back

Preview of the back of card 4

Card 5

Front

Capacity of the heart to generate its own electrical impulse, causes cardiac muscle to contract

Back

Preview of the back of card 5
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