2. The Cardiovascular System Flashcards
What are the 3 layers of the heart?
- epicardium: protective outer
-Myocardium: muscular middle→ can undergo hypertrophy
-endocardium: thin inner
What are the 3 types of muscles?
- Skeletal muscle, cardiac muscle, smooth muscle ( arteries, veins, capillaries)
Maximal exercise definition
Physical activity performed at highest intensity level of an individual achieve, pushes body to limit
→ short duration, at/near 100% effort.
Examples of maximal exercise
Sprinting, HIIT, 1 rep max
Benefits of maximal exercises
Enhances max. Strength, speed & power, improve anaerobic capacity
Submaximal exercise definition
Physical activity performed at intensity level below max. Capacity of individual
→ longer duration, 70 - 85% max. HR
Examples of submaximal exercise
Brisk walking, moderate jogging
Benefits of submaximal exercise
Improves cardiovascular health, endurance & overall fitness
What are the 3 main parts of the cardiovascular system
Heart, blood vessels, blood
CV system function
Deliver oxygen & nutrients and remove waste products from body’s cues and regulate temperature
What is the pulmonary circuit?
Transports deoxygenated blood from heart to lungs & oxygenated from lungs to heart
What is the systemic circuit?
Transports oxygenated blood from the heart to tissues & deoxygenated from tissue to heart
What is the conduction system?
Cells in the heart that send signals to cause the heart to contract
Conduction system order
- SA node (sinoatrial)
- AV node (atrioventricular)
- Bundle of his
- Purkinje fibres
SA node’s role
Heart’s natural pacemaker, sends electrical signal that tells heart to beat, starts right in atrium to fill
AV node’s role
After signal from SA node causes atria to contract, AV node slows signal down before sending it to the ventricles. This delay allows the atria to empty fully before the ventricles contract
Bundle of His role
Electrical signal traces from AV node to bundle of His which splits into 2 branches, one for each ventricle
Purkinje fibres role
Spread electrical signal throughout ventricles causing them to contract & pump blood out of heart to rest of body
Name for SA node
Heart’s natural pacemaker
Heart rate definition.
Number of times the heart beats per minute (bpm)
Average heart rates
Trained:
-rest: 70 bpm
- submax: 100 -130 bpm
- max: 220- age
Untrained:
- rest: 50 -60 bpm
- submax: 95-120 bpm
- max: 220 -age
Bradycardia definition.
Decrease in resting HR to below 60 bpm
Stroke volume definition
Volume of blood pumped out of the left ventricle per beat (L)
SV formula
End diastolic value (EDV) - end systolic value (ESV)
Stroke volume values
Trained:
- rest → 100 ml
- submax → 160 - 200 ml
- max → 160 -200 ml
Untrained:
-Rest →70ml
- submax → 110ml
-Max→ 110ml
Diastole definition
Relaxation phase, ventricles fill
Systole definition
Contraction phase, ventricles empty
What factors determine stroke volume?
- venous return→ blood returned to heart via veins
- if VR increases, so does SV
- elasticity of cardiac fibres sees a degree of stretch during diastole phase; greater stretch → greater contraction→ greater SV (Frank starling’s law)
- contractility of cardiac tissues; greater contraction → greater force
Venous return definition
Amount of deoxygenated blood returning back to the heart (right atrium)
What are the 5 mechanisms of venous return?
Pocket valves, gravity, smooth muscle, respiratory pump, skeletal muscle pump
Pocket valves function (VR)
Prevent backflow of blood, flows in one direction, prevent blood pooling
Skeletal muscle pump function (VR)
Veins situated between skeletal muscles which help squeeze blood back to the heart when they contract & relax
Respiratory pump function (VR)
During exercise, breathing deeper increases pressure in the thorax & abdomen
Smooth muscle function (VR)
Thin layer of smooth muscle helps squeeze blood back towards heart → vasodilation & vasoconstriction of blood vessels
Gravity function (VR)
Blood from upper body aided in its return to heart as graving allows it to easily flow down
Cardiac output (Q) definition
Volume of blood pumped out of left ventricle per minute (L/min)
Cardiac output values
Trained:
-Rest→ 5L/min
-Submax→ 15 - 20 l/min
-Max → 30 -40 L/min
Untrained:
-Rest→ 5 L /min
- submax → 10-15 l/min
- max → 20 -30 l/min
Changes to HR during exercise
HR increase, how much depends on intensity of exercise, direct proportion, greater intensity = greater HR
Anticipatory rise
Hormonal action of adrenaline secretion stimulates SA node for heart to beat faster
Sharp rise at start of exercise
Due to mainly anaerobic exercise (heart beats rapidly to meet increased demand for oxygen by supplying more oxygenated blood to working muscles
Heart rate continues to rise
Due to maximal workload stressing anaerobic system athlete reaches 90 - 100% max effort)
Steady state exercise
Able to meet oxygen demands required for activity (reaching a plateau as intensity is sustained)
Rapid decline as exercise stops
Decreased demand for oxygen in working muscles
Slow recovery
Body systems return to resting levels (but Mr remains elevated to remove waste products
Changes in stroke volume
- SV↑ as exercise increases
- only increases up to 40-60% of max. Intensity
- SV starts to level / drop
- due to shorter diastolic phase
- less time to fill with blood
- volume pumped out decreases
Changes in cardiac output
- ↑ during exercise
- through training heart gets bigger & stronger (hypertrophy)
- bigger heart → more blood can be pumped out by left ventricle per beat (SV)
- however resting HR will ↓
-at rest: ↑ SV x ↓ HR = Q stays same - during exercise: HR & SV ↑
- during exercise: ↑SV &↑ HR = YQ
Cardiac control centre
Central nervous system & peripheral nervous system
Central nervous system
Brain & spinal cord
Peripheral nervous system
Cranial & spinal nerves
- sensory division & motor division
Sensory division
Somatic & visceral sensory nerve fibres → conduct impulses from receptors to CNS
Motor division
Motor nerve fibres→ conducts impulses from CNS to effectors
- autonomic & somatic nervous systems
Autonomic nervous system
-Involuntary
→ conduct impulses from CNS to cardiac & smooth muscles and glands
- sympathetic & parasympathetic division
Sympathetic division
Mobilises body systems during activity (fight or flight)
- releases hormones to ↑ HR
Parasympathetic division
Conserves energy, promotes ‘housekeeping’ functions during rest
-Release hormones to ↓ HR
Somatic nervous system
Conduct impulses from CNS to skeletal muscles
Cardiac control centre role
- Found in medulla oblongata → part of ANS
- sympathetic nervous system (SNS) ↑ HR via accelerator nerve
- parasympathetic nervous system (PNS) ↓ HR via vagus nerve
- accelerator & vagus nerve send messages to SA node to ↑ or ↓ HR
What happen to SNS during exercise?
SNS becomes more dominant & takes control of HR
- neural control, nominal control, intrinsic control
What happens to PNS at rest?
PNS in control of HR
- vagus nerve releases acetylcholine
Internal & external ways of controlling HR
Internal → intrinsic
External → neural, hormonal
Neural control
-Receptors pick up changes in body as a result of increased physical activity
- send messages to CCC in medulla oblongata
- ANS sends messages to SA node to speed up / slow down HR.
Proprioreceptors
Pick up movement in joints & muscles
- muscle length = muscle spindles; muscle tension= Golgi tendon organs
In creased intensity generally means increased movement
Chemoreceptors
-Inside muscle tissue, a orca, carotid artery
Pick up chemical changes such as lower blood pH due to increased CO2 & lactic acid, increased O2
Baroreceptors
- Aorta, carotid artery
Changes in blood pressure due to exercise intensity
Thermoreceptors
-In skin, skeletal muscle, liver
Changes in body temp, ↑ intensity = ↑ temp
Hormonal control
- Before & during exercise, adrenaline & noradrenaline released into bloodstream from adrenal medulla in kidneys
- act directly on SA node stimulating ↑ HR & Sv
-Explains anticipatory rise - both adrenaline & noradrenaline aid redistribution of blood via vasodilation & vasoconstriction
-When intensity ↓, hormone acetylcholine begins to ↓hr
Intrinsic control
The heart rate internally controlling itself
- temperate: as temp. Of cardiac muscle ↑ it speeds up nerve impulses causing ↑ HR
- starling’s law: as venous return ↑ so does SV
Components of blood
45% cells
55% plasma
What is plasma made of ?
approx 90% water
- plasma proteins
-Electrolytes
-Nutrients
-Waste products
-Hormones
-Gases
What are the cells in the blood?
- Red blood cells → O2 & CO2 transport
- white blood cells → immune system, attack pathogens
- platelets → clotting
What are the functions of blood?
- transports O2 & CO2
-Transports nutrients
-Remove waste products
-Thermoregulation
-Protect against infection - clotting & injury repair
-Regulation of fluid balance
Arteries - structure & function
-Thick wall
-10-25 mm diameter
- no valves
-High pressure
- oxygenated blood, except pulmonary
- flow away from heart
-Transports oxygenated blood to tissues
Arteriole - structure & function
- Thinner wall
-30 -100 μm diameter - no valves
-Lower pressure than arteries - oxygenated blood
- flows away from heart towards capillaries
- regulate blood flow, control pressure (constrict & dilate), direct blood to active tissue
Capillary - structure & function
- Very thin (for diffusion)
- 5-10 μm diameter
- no valves
-Low pressure - oxygenated in systemic, deoxygenated in pulmonary
- flow: arteriole → capillary → venule
- exchange of gases, waste products &nutrients; temp regulation; aid fluid balance
Venule - structure & function
-Thin
-20-250 μm
- some small ones have valves
- very low pressure
- deoxygenated blood
-Flows towards heart
- collect deoxygenated blood from capillaries, drain capillary bed, fluid exchange, regulate venous pressure
Veins - structure & function
- Thin
-1 mm -3 cm diameter - no valves
- very low pressure
- deoxygenated blood except pulmonary
- flow towards heart
- transport deoxygenated blood to heart, storage reservoir for blood, regulate blood volume & pressure
Redistribution of blood during exercise is also known as….
Vascular shunting
Proportion of blood flow at rest / exercise
Rest: 80% to brain, kidneys, skin etc to carry out normal bodily functions
Exercise: 80% to working muscles away from non-essential organs
Vascular shunting definition
Action of smooth muscle around arterioles (vasoconstriction & vasodilation) & action uf precapillary sphincters will direct blood to where it is needed & restrict it where it isn’t needed.
Vasodilation definition
Widening of blood vessels due to relaxation of muscular walls
→ increases blood flow, decreases pressure
Vasoconstriction definition
Narrowing of blood vessels due to tightening of muscular walls
→ decreases blood flow, increases pressure
Pre capillary sphincters definition
Small ring of muscle located at entrance of capillaries
Controls blood flow into capillaries by opening & closing
Importance of blood redistribution
-Increased supply of oxygen to working muscles
-More blood to skin to regulate body temp to dissipate heat
-Remove waste products from muscles
- direct more blood to heart as it needs more oxygen
Vasomotor control centre (VCC) allowing redistribution of blood (neural control)
- Chemoreceptors: chemical changes in blood→ increased carbonic acid & lactic acid
- baroreceptors: changes in systolic blood pressure in aorta & carotid artery
- receptors send into to VCC in medulla oblongata
-Arterioles have middle layer of muscle connected to VCC stimulated by sympathetic nerve
-Increased ins action causes vasoconstriction towards NEOs which increases blood pressure & redirects to muscle - decides if pre capillary sphincters should open/close
