AS Applied Anatomy and Physiology Flashcards
What is the function of the blood transport system?
To deliver blood around the body to get oxygen to respiring tissues
How is blood transported around the body?
In blood vessels
What are the roles of the blood?
- deliver oxygen to working muscles
- remove waste products
- transport nutrients, glucose and hormones
- thermoregulation
- protect body from infection
- clots to prevent blood loss
What are the 2 parts to the double circulatory system?
Systemic and pulmonary
What is the systemic circulatory system?
Pump blood from heart to body and back via the aorta and vena cave
What is the pulmonary circulatory system?
Pump blood from the heart to lungs and back via the pulmonary artery and vein
What is the role of the septum?
Split the heart into left and right
Where is the SA node found?
Right atrium
Which ventricle has the thickest walls and why?
- left ventricle
- has the highest pressure
What are the semi lunar valves?
- found between the ventricles and the arteries
- prevent the back flow of blood
What is the cardiac conduction system?
- SA node emits an electrical impulse
- impulse spreads throughout the atria causing them to contract
- impulse arrives at AV node
- AV node delays transmission for 0.1s allowing atria to contract
- impulse sent down septum via bundle of His
- purkinje fibres spread impulse throughout muscular walls
- ventricles contract
What does myogenic mean?
Generates its own impulse/self regulating e.g. the heart
Where is the neural control mechanism located?
In the medulla oblongata
Are the neural control mechanisms voluntary or involuntary?
Involuntary
What is the role of the sympathetic nervous system?
Sends out impulses to SA node to increase heart rate before and during exercise
What is the role of the parasympathetic nervous system?
Sends impulses to SA node to decrease heart rate after exercise
What is the role of receptors?
Detect changes in the body
What is the role of chemoreceptors?
- detect changes in blood acidity
- during exercise there is an increase in blood acidity so the sympathetic NS is stimulated causing heart rate to increase
What is the role of baroreceptors?
- detect blood pressure changes
- changes in pressure sends signals to medulla oblongata
- stretch at high arterial pressure to allow heart rate to decrease
What is the role of proprioceptors?
- detect changes in muscle movement
- located in muscles, tendons and joints and medulla oblongata
- detects movement at start of exercise and sends impulse to medulla oblongata to stimulate sympathetic NS
What is anticipatory rise?
Increase of heart rate before exercise (mimics the sympathetic NS)
What hormone causes anticipatory rise?
Adrenaline
What is stroke volume and what happens during exercise?
- volume of blood leaving the left ventricle per beat
- increases during exercise
- 70ml per beat
What is venous return and what happens to it during exercise?
- volume of blood returning to the heart via veins
- increases during exercise
- directly proportional to stroke volume
What is ejection fraction?
- percentage of blood pumped out of the left ventricle per beat
- average is 60%
What is the elasticity of cardiac fibres?
The degree of stretch of cardiac tissue during the diastole phase of the cardiac cycle
What is Starlings Law?
The more the cardiac fibres stretch the greater the force of contraction which increases ejection fraction
What is bradycardia?
A decrease in resting heart rate
What is CHD?
- coronary heart disease
- coronary arteries became blocked up due to fatty deposits
- atherosclerosis
- fatty deposits are called atheroma
What is high blood pressure?
- a high force exerted by the blood against the blood vessel walls
- can be reduced by aerobic exercise
What are LDLs?
- low density lipoproteins
- bad cholesterol
- transported in blood to the tissues
What are HDL?
- high density lipoproteins
- good cholesterol
- transport excess cholesterol in the blood to the liver where is it broken down
What is a stroke?
- occurs when the blood supply to the brain is cut off causing damage to brain cells
- aerobic exercise can reduce risk of stroke by 27%
What is cardiovascular drift?
As heart rate increases, over time stroke volume decreases
What are the causes of cardiovascular drift?
- reduction in fluid in blood due to vasodilation
- reduces venous return and stroke volume
- increase in cardiac output due to thermoregulation
What is the structure and function of arteries?
- thick walls
- made of elastic and muscle fibres
- can vasoconstrict and vasodilate
- carry blood away from heart
- main one is aorta
What is the structure and function of arterioles?
- small arteries
- made of elastic and muscle fibres
- vasodilate and vasoconstrict
What is the structure and function of capillaries?
- tiny blood vessels supplying nutrients to cells and removing waste products
- 1 cell thick
- around lungs and muscles
What is the structure and function of veins?
- thin walls
- have valves
- carrying blood to the heart
What is the structure and function of venuoles?
- small veins
- have pocket valves
What is blood pressure?
Force exerted by blood against the blood vessels walls
How do you calculate blood pressure?
Blood flow x resistance
What is systolic pressure?
Pressure of contraction
What is diastolic pressure?
Pressure of relaxation of heart
What are the 4 venous return mechanisms?
- skeletal muscle pump
- pocket valves
- involuntary/smooth muscle in vein walls
- respiratory pump
What is the skeletal muscle pump?
Contracting muscles squeeze the walls of the veins to pump blood to the heart
What are pocket valves?
Prevent back flow of blood and ensures it is unidirectional
What is the function of smooth muscle in vein walls?
Contract when stimulated by sympathetic nervous system
What is the role of the respiratory pump?
Changes in pressure in the thorax during inspiration compressing the veins and squeezes blood towards the heart
How much oxygen combines with haemoglobin during exercise?
97%
How many oxygen molecules can a fully saturated haemoglobin molecule carry?
4
What stores oxygen in the muscles?
Myoglobin as it has a higher affinity to oxygen than haemoglobin
What is shown in the oxygen dissociation curve?
- at low partial pressures of oxygen, haemoglobin unloads its oxygen
- at high partial pressures of oxygen, haemoglobin loads its oxygen
What is the Bohr shift?
- due to more carbon dioxide in the blood there is a low pH
- curve shifts to the right
- haemoglobin unloads easier as there is a reduced affinity for oxygen
What factors cause the Bohr shift?
- increased blood temperature
- partial pressure of carbon dioxide increases
- a lower pH
What is vascular shunting?
Directing blood to skeletal muscles for respiration during exercise
How much blood is directed to the muscles at rest and during vigorous exercise?
At rest is 15-20% and during exercise is 80-85%
What is the importance of redistribution of blood?
- increased supply of oxygen to working muscles
- remove waste products
- ensure move blood to skin for thermoregulation
- direct more blood to heart as it is a muscle and requires extra oxygen during exercise
What is vasodilation?
Blood vessels around skeletal muscles widen to increase blood flow to muscles
What is vasoconstriction?
Blood vessels narrow around nonessential organs to decrease blood flow to muscles e.g. intestines
What is A-VO2 difference?
- arterio-venous difference
- the difference between the oxygen content of arterial blood arriving at the muscles and the venous blood leaving the muscles
Why is A-VO2 difference low at rest?
Not much oxygen is required by the muscles
Why is A-VO2 difference high during exercise?
- more oxygen is needed from blood for the muscles to respire
- this will cause an increase in gas exchange at alveoli
What does regular aerobic training do to A-VO2 difference?
- increases it
- trained individuals can extract a greater amount of oxygen from the blood
What are the alveoli and the adaptations?
- responsible for gas exchange between the lungs and blood via diffusion
- thin walls (1 cell thick), short diffusion pathway
- extensive capillary network, excellent blood supply
- lots of alveoli that are highly folded, large surface area
How do the mechanics of breathing work?
- air moves from high to low pressure down a pressure gradient
- the steeper the gradient the faster the air flows
How does inspiration work?
- external intercostal muscles contract
- ribs pulled up and out
- diaphragm contracts and flattens
- volume of thorax increases
- pressure decreases compared to atmosphere so air moves in down its pressure gradient
How does expiration work?
- internal intercostal muscles contract
- ribs move down and in
- diaphragm relaxes and domes up
- volume of thorax decreases
- pressure increases compared to the air so air moves out down its pressure gradient
What is tidal volume and what happens during exercise?
Volume of air inspired/expired per breath, 0.5L at rest and increases during exercise
What is minute ventilation and what happens during exercise?
The volume of air inspired/expired per minute (breathing rate x tidal volume) and increases during exercise
What is inspiratory reserve volume and what happens during exercise?
The extra volume of air you can inspire which decreases during exercise as tidal volume increases
What is expiratory reserve volume and what happens during exercise?
The extra volume of air you can expire which decreases during exercise as tidal volume increases
What is residual volume and what happens during exercise?
The volume of air left in the lungs after breathing which remains the same during exercise
What does a spirometer measure?
Measures the volume of air inspired/expired
What is partial pressure?
The pressure a gas exerts in a mixture of gases (mmHg)
How does gas exchange work at the lungs?
- higher partial pressure of oxygen in the alveoli so oxygen moves down concentration gradient from alveoli to blood
- higher partial pressure of carbon dioxide in the lungs so carbon dioxide moves down concentration gradient from blood to alveoli
How does gas exchange work at the muscles?
- higher partial pressure of oxygen in the blood so oxygen moves down concentration gradient from blood to muscles
- higher partial pressure of carbon dioxide in the muscles so carbon dioxide moves down its concentration gradient from muscles to blood
What is the effect of exercise on the diffusion gradient?
- muscles use more oxygen
- steeper diffusion gradient
- more oxygen diffuses into blood and into muscles
How do we regulate pulmonary ventilation during exercise?
- neural control (brain and nervous systems)
- chemical control (blood acidity)
- hormonal control
What is the role of the sympathetic and parasympathetic nervous system in regulation of pulmonary ventilations?
- the sympathetic system increases breathing rate before and during exercise
- the parasympathetic system decreases breathing rate after exercise
What is the respiratory centre?
- located in the medulla oblong at a
- controls rate and depth of breathing using neural and chemical control
How do we control breathing during exercise?
- increased carbon dioxide in blood stimulates the respiratory centre to increase breathing rate
- the inspiratory centre sends out impulse in phrenic nerve to inspiratory muscles causing them to contract
- can also be stimulated by blood acidity
What is the inspiratory centre?
Responsible for inspiration and expiration
What is the expiratory centre?
Stimulates expiratory muscles during exercise
What are factors that control breathing?
Mechanical factors, baroreceptors and stretch receptors
What are mechanical factors that control breathing?
Proprioceptors that are located in joints and muscles and provide feedback to RC to increase breathing
What are baroreceptors in the control of breathing?
Decrease in blood pressure detected in aorta and carotid results in increased breathing rate
What are stretch receptors in the control of breathing?
Prevent over inflation of lungs by sending impulses to the expiratory centre
How does adrenaline regulate breathing?
Before exercise the brain sends an impulse to adrenal glands which secretes adrenaline into the blood to increase breathing rate in preparation for exercise
How does minute ventilation during sub maximal exercise change?
- anticipatory rise as a result of adrenaline
- rapid rise due to an increase in acidity and an increase in temperature and muscle movement (medulla oblongata increase BR an TV)
- levels off as a plateau is met
- rapid decline as exercise stops
- slower decrease due to need for oxygen to get rid of lactic acid
What are the effects of training on respiration?
- small increase in lung volumes and capacities
- increased number of red blood cells (haemoglobin)
- increase in capillary density
- increased number of mitochondria
- energy demands met at lower minute ventilation
- faster recovery post exercise
How does smoking affect the respiratory system?
- irritates the trachea and bronchi (cilia)
- reduced lung functions
- damage cilia and alveoli
- reduced efficiency of gas exchange leading to an increase risk of COPD
- oxygen transport declines as CO combines with haemoglobin more readily than oxygen a it has a higher affinity
What is the autonomic nervous system?
Regulates the function of internal organs e.g. heart and some skeletal muscles, and is involuntary
What response does the sympathetic NS elicit?
Fight or flight
What response does the parasympathetic NS elicit?
Rest and relax
What determines your proportion of muscle fibres
Genetics
What are slow twitch muscle fibres?
- type 1
- aerobic exercise
- e.g. marathon
What are fast twitch muscle fibres?
- type 2a and 2x
- anaerobic
- example of type 2a is 400-800m
- example of type 2x is 100m
What are the functional characteristics of type I muscle fibres?
- slow contraction speed
- low force produced
- high resistance to fatigue
What are the structural characteristics of type I muscle fibres?
- small motor neurone size
- high mitochondrial density
- high capillary density
What are the functional characteristics of type IIa muscle fibres?
- fast contraction speed
- high force produced
- moderate resistance to fatigue
What are the structural characteristics of type IIa muscle fibres?
- large motor neurone size
- moderate mitochondrial density
- moderate capillary density
What are the functional characteristics of type IIx muscle fibres?
- very fast contraction speed
- very high force produced
- very low resistance to fatigue
What are the structural characteristics of type IIx muscle fibres?
- very large motor neurone
- very low mitochondrial density
- vey low capillary density
What is a motor unit?
- a motor neurone and its muscle fibres
- there is only one type of muscle fibre in a unit
What do motor neurone branches end in?
Neuromuscular junctions
What is the difference between small and large motor units
- small motor units are used for fine motor control (e.g. eye movement)
- large motor units are used to gross motor control (e.g. quadricep movement)
What is the all or nothing law?
Once a motor neurone stimulates muscle fibres, all fibres contract or no fibres contract
What must be crossed for a motor unit to contract?
The threshold
What is wave summation?
The greater the frequency if stimuli the greater the tension so the greater the force of contraction
What is a tetanic contraction?
The greater the frequency of stimuli the less time for rest so there is a build up of calcium so there is a high force, smooth, sustained contraction