cardiac system Flashcards
Name the 4 chambers of the heart
R/L atrium
R/L ventricle
Name the pathway of blood through 4 vessels in the heart
VENA CAVA - deox in from body
PULMONARY ARTERY - deox out to lungs
PULMONARY ARTERY - oxygenated in from lungs
AORTA - oxygenated out to body
Roles of blood
- transporting co2 to the lungs to be removed during exhalation
- Transport glucose to working muscles
- Helps control body temperature
(vasoconstriction/dilation) - Protects body from infection
- clots to prevent blood loss
Name the two blood transport systems in the body
1.Pulmonary circulation
2. systematic circulation
Direction of blood in the pulmonary circulation system
Heart -> lungs -> heart
Direction of blood in the systematic circulation system
heart-> body tissues -> heart
What do the two blood transport systems make up?
the double circulatory system
Name the 5 blood vessels
Artery
Arterioles
capillaries
venules
veins
Name a characteristic of the Artery
- thick elastic walls that withstand pressure - after the walls stretch they recoil helping force blood towards the body
Name and explain 3 characteristics of the capillaries
- one cell thick - diffusion distance short for maximum gas exchange
- small diameter - to slow rate of bloodflow for maximal gas exchange
- Large surface area - large contact area for incr opportunity for maximal gas exchange
Define vasoconstriction
Reduction in the diameter f blood vessels which reduces the flow of blood into the capillaries
Define vasodilation
increase in the diameter of blood vessels which increases the flow of blood into the capillaries
What are vasoconstriction and vasodilation controlled by
the sympathetic nervous system
What is the venous return mechanism?
How the deoxygenated blood returns to the right side of the heart via the venules, veins and vena cava.
what happens to venous return during exercise?
when we exercise venous return increases so that more oxygen is pumped from the heart to the body.
venous return is made more difficult by the low pressure of blood in veins and as the blood has
Give the 4 components of the venous return system
- skeletal muscle pump
- respiratory muscle pump
-involuntary/ smooth muscle - pocket valves in veins
What is vascular shunt?
The way the body redistributes the blood around the body so that the working muscles receive an increased proportion
Defined as the redistribution of blood flow during exercise
How is vascular shunt achieved ?
- Vasodilation - of arteries and arterioles to working muscles to increase blood flow and gas exchange
- Vasoconstriction - arteries and arterioles constrict to decrease blood supply to the liver, gut and kidneys.
- pre-capillary sphincters - regulates bloodflow by vasoconstricting or dilating
❗ Describe how skeletal muscle pump and valves work together to return blood to the heart (3)
- skeletal muscles contract more during exercise, compressing veins
- squeezing veins forcing blood back to the heart
- one way pocket valves - prevent backflow
During vascular shunt what body parts receive..
an increase
a decrease
the same volume of blood
- coronary vessels - to the heart / the skin - help body lose heat
- the gut, liver and digestion system
- brain - needs to function at work and rest. needs constant supply of glucose
❗ Explain how redistribution of blood occurs during exercise (3)
- Sympathetic nervous system controls vascular shunt
- vasodilation to areas needing blood - to incr oxygenated blood flow
- vasoconstriction to non working - eg gut, liver and kidneys - so more blood can be distributed to working muscles
❗ Explain why bloodflow to brain remains the same during rest AND maximum effort (2)
- the brain function is maintained during exercise
- Therefore oxygen and glucose are still required to be delivered
How is blood pressure created ?
as the heart pumps blood through vessels, the walls of the vessels offer resistance
What does blood pressure in vessels depend on
Whether the blood has been forced through the vessels, or this forced flow of blood is reduced
The further away from the heart the blood flow is the lower the pressure (heart is source of pressure)
systolic pressure
pressure of the heart contracting
diastolic pressure
pressure of the relaxed heart
order the vessels in terms of blood pressure from highest to lowest
arteries
arterioles
capillaries
venules
veins
what causes blood pressure to decrease between arterioles and capillaries
smaller vessels have a larger SA (cross sectional area)
leads to more friction from vessel walls - reducing blood pressure
as the blood moves from arteries to arterioles to capillaries the total SA incr, friction incr, blood pressure drops
describe patterns of blood velocity in the vessels
arteries FAST
arterioles
capillaries SLOW
venules
veins FAST
why do capillaries need a lower blood velocity ?
for maximal diffusion to occur.
eg gas exchange
❗ Describe how the cardiac system causes the heart to contract.(7)
- Heart is myogenic (generates its own impulse through SA node)
- SA node emits an impulse
- atria contract
- impulse sent to AV node where its delayed
- sent through bundle of his
- spread through perkinji fibres in ventricle walls
- ventricles contract
the heart is self regulating - what is the term for this?
myogenic
where is the SA node located ?
right atria of the heart
stroke volume
the volume of blood leaving the left ventricle per beat
heart rate
number of beats per minute
cardiac output ( and equation)
the volume of blood leaving the left ventricle per minute
CO = SV x HR
Ejection fraction
proportion of / percentage of all blood pumped out left ventricle per beat
average resting HR
60bpm
where is the neural control mechanism located ?
Medulla oblongata
What does the neural control mechanism control
unconscious and involuntary activity
- HR
Name the two components of the neural control mechanism
sympathetic nervous system
parasympathetic nervous system
describe the role of the sympathetic nervous system
send out impulses to SA node to INCREASE heartrate
describe the role of the parasympathetic nervous system
send out impulses to SA node to DECREASE heartrate
❗ describe what is meant by anticipatory rise and name the hormone that causes it (2)
1.adrenaline
2. causes HR to increase before exercising
Name 3 receptors that send impulses to increase HR
chemoreceptors
baroreceptors
proprioceptors
❗ explain how rising levels of co2 cause an increase in cardiac output (4)
1.exercise causes an incr in co2 levels which incr blood acidity
2. change in blood PH detected by chemoreceptors
3. an impulse is sent to the medulla oblongata in CCC - incr stimulation of the sympathetic nervous system
4. incr impulse emission from SA node -incr HR
5. CO= SR x HR - if HR incr so will CO
Explain the roles of the receptors controlling HR
chemoreceptors - detect change in blood PH /acidity / conc of CO2
baroreceptors - detect changes in blood pressure
proprioceptors - detect muscle movement / contraction
maximum HR equation
220 - age
Explain Starlings Law
during exercise - venous return incr meaning a larger volume of blood in the heart
the elastic ventricle walls are stretched MORE causing a more forceful counter-contraction
causing an incr stroke volume
State starlings law
increased venous return leading to an increased stroke volume during exercise
what happens to HR when exercise stops?
- HR decr quickly
- followed by a second, slower decr to return to resting rate
- during this second phase HR remains slightly elevated to make up for EPOC and waste products (eg lactic acid )
Name and describe the 2 main effects of training on the cardiovascular system
BRADICARDIA- a reduction in resting HR below 60bpm
CARDIAC HYPERTROPHY - increase in thickness of the cardiac muscle in the left ventricle making it stronger - this increases stroke volume
what might hypertrophy result in?
a higher stroke volume
why does bradycardia occur ?
CO=SVxHR
There’s an incr in SV due to hypertrophy
BUT
cardiac output remains constant
so HR must decr
name other effects of training on the cardiac system
- lower resting HR
- Increased capillarisation
3.Increased Ejection fraction - Increased Stroke volume
- Increased Cardiac output
❗ use starlings law of the heart to explain how stroke volume increases when running (3)
- incr venous return
- greater diastolic filing
- cardiac muscle stretched
4.more powerful counter contraction
define systole
contraction and ejection of the heart
define diastole
relaxation and filling of the heart
❗ Explain the term cardiovascular drift (3)
- As water is lost through sweat in exercise,
- The blood becomes more viscous, bloodflow slows and venous return decr
- reduced stroke volume
- To maintain cardiac output heart rate must increase (CO = SV x HR)
where is the tricuspid and bicuspid valve located?
tricuspid - right atria
bicuspid - left atria