Cardiovascular System

Question 1

functions

Answer 1

transport of o2, co2, nutrients, waste products
maintenance of pH and hydration
protection- transport of white blood cells
thermoregulation

Question 2

components

Answer 2

fluid medium= blood
system of channels= arteries, veins, capillaries, closed loop channel
pump= heart

Question 3

divisions- pulmonary circuit

Answer 3

transports blood to and from the lungs
includes pulmonary arteries + veins, capillaries in lungs

Question 4

systemic circuit

Answer 4

transports blood around the rest of the body- under large amounts of pressure
includes capillaries in head, neck, abdominal organs, upper + lower limbs + systemic veins

Question 5

location of heart

Answer 5

located in thoracic cavity, near anterior chest wall, directly posterior to the sternum
between 2 lungs
size of heart affected by training status, size of individual, sex + age
apex of heart at 5th intercostal space

Question 6

structure + function of the heart

Answer 6

functions as a double pump
atria- RA receives blood from systemic circuit and passes it to the right ventricle
LA receives blood from pulmonary circuit and passes it to the left ventricle

ventricles- RV receives blood from RA and pumps it into pulmonary circuit
LV receives blood from LA and pumps it into the systemic circuit

systole- contraction diastole- relaxation

Question 7

valves

Answer 7

atrioventricular valves
right= tricuspid valves
left= bicuspid
chordae tendinae- heart strings

Question 8

heart wall- pericardium

Answer 8

pericardium- fibrous tissue, stabilises heart position, lubrication (through pericardial fluid in pericardial space)
made of:
outer fibrous layer
parietal layer (outer serous)
visceral layer (inner serous, epicardium)

Question 9

heart wall- myocardium

Answer 9

thick muscular layer between epicardium + endocardium
thickness varies according to chamber
large central nucleus + many mitochondria
interconnections with other cardiac cells via intercalated discs
involuntary, myogenic controlled by ANS and endocrine system

Question 10

intercalated discs

Answer 10

junctions between cardiac cells
2 components:
gap junctions- allowing for depol to pass through cells synchronising muscle contraction
desmosomes- bind adjacent myocytes together

Question 11

endocardium

Answer 11

covers all inner surfaces of the heart:
internal chambers + heart valves
consists of epithelial tissue and is continuous with the epithelium of the great vessels

Question 12

ventricular differences

Answer 12

wall of LV is thick + cylindrical shape
LV delivers blood into systemic circuit where pressure is 80-100mmHg
pumping blood around systemic circuit requires 4-6 times more pressure than pulmonary circuit
wall of RV is thin as delivers blood to pulmonary circuit where pressure is 15mmHg

Question 13

heartbeat

Answer 13

single contraction of heart
entire heart contracts in series- atria then ventricles
2 types of cardiac muscle cells:
contractile cells- produce contractions
cardiac pacemakers (nodal/ conducting)- SAN, AVN, purkinje fibres- control and coordinate contractile cells

Question 14

cardiac cycle

Answer 14

1. SAN (pacemaker) - creates periodic electrical impulses
2. stimulus spreads across the atrial surfaces and reaches the AV node where there is a delay to allow emptying of atria
3. travels along interventricular septum to purkinje fibres
4. impulse is distributed by purkinje fibres and relayed throughout the ventricular myocardium, atrial contraction is completed and ventricular contraction begins

Question 15

heart rate regulation- autonomic NS

Answer 15

sympathetic - increases HR
parasympathetic (vagal) - slows down heart rate
both innervate the heart directly at SA node
at rest, para NS dominates
during exercise symp NS dominates

Question 16

catecholamines- epinephrine

Answer 16

released by adrenal medulla upon activation of sympathetic nerves innervating the tissue
released during stress, exercise + activity
increases HR and contractility (inotropy)
works by binding to adrenergic receptors on the heart

Question 17

norepinephrine

Answer 17

noradrenaline
initially increases HR and contractility but with longer exposure can result in decreasing heart rate
released by adrenal medulla (20%) but mostly from spill over from sympathetic nerves innervating blood vessels
works by binding to adrenergic receptors on the heart

Question 18

chemoreceptors

Answer 18

receptors that monitor chemical characteristics of the blood and help regulate function of cardiovascular and respiratory systems
monitor blood co2 and pH
peripheral - in carotid + aortic bodies
high co2 + low pH= increase HR
low co2 + high pH= decrease HR

Question 19

barorecpetors

Answer 19

mechanoreceptors that sense changes in blood pressure on a beat to beat basis
carotid sinus- senses increase and decreases
aortic arch- senses increase only
low blood pressure= low stretch of vessel= less stretch of receptor= decreased afferent firing = increased efferent sympathetic firing and decrease parasympathetic firing

Question 20

circulatory vessels

Answer 20

arterial system- high pressure system delivering blood away from heart (arterioles and arteries)
venous system- veins and venules, under low pressure, take a long time to return blood back to heart
capillary bed- thoroughfare channels provide faster exchange, pre capillary sphincters control rate of blood flow into capillary

heart > artery > capillary > venule > vein > heart

Question 21

distribution of blood volume

Answer 21

systemic venous system= 60%
large veins, large venous networks, venules + medium size veins
pulmonary circuit= 9%
heart= 7%
systemic arterial system = 13%
systemic capillaries = 7%

Question 22

blood vessels

Answer 22

three layers
1. tunica intima- inner layer (encompasses)
2. tunica media- middle layer
3. tunica externa- outer layer
common between veins and arteries but different characteristics between the two

Question 23

endothelium

Answer 23

releases vasoactive substances which affect vascular tone, blood pressure and blood flow
maintains vascular homeostasis
vasodilators- nitric oxide
vasoconstrictors - endothelin
damage to endothelium = more likely to get blood clots

Question 24

tunica intima

Answer 24

encompasses endothelial lining and connective tissue layer
internal elastic membrane in arteries providing elastictiy to tunica intima
in arteries- usually ripples due to vessel contraction
in veins- often smooth

Question 25

tunica media

Answer 25

concentric sheets of smooth muscle in loos connective tissue with elastic fibres in arteries and collagen in veins encircles the endothelium that lines the lumen (interior space) of the blood vessel binds to inner and outer layers external elastic membrane (arteries)- separates tunica media from tunica externa

Question 26

tunica externa

Answer 26

anchors vessels to adjacent tissue contains collagen + elastic fibres, smooth muscle cells (in veins) vasa vasorum- vessels of vessels -small arteries and veins in walls of large arteries and veins- serve cells of tunica media and tunica externa

Question 27

type of artery

Answer 27

elastic artery- high elastin content in tunica media, internal elastic membrane in tunica intima muscular artery arteriole-

Question 28

capillary

Answer 28

endothelial tube inside thin basement membrane no tunica media no tunica externa diameter similar to that of RBC types- continuous, fenesrtated + sinusoid

Question 29

continuous

Answer 29

found in all tissues except epithelia and cartilage have complete endothelial lining permit diffusion of water, small solutes and lipid soluble materials - block blood cells and plasma proteins specialised continuous capillaries in CNS and thymus with restricted permeability (blood brain barrier)

Question 30

fenestrated capillary

Answer 30

have pores in endothelial lining permit rapid exchange of water and larger solutes found in chloroid plexus (brain), endocrine organs, kidneys + intestinal tract

Question 31

sinusoid

Answer 31

have gaps between adjacent endothelial cells permit free exchange of water and large plasma proteins found in liver, spleen, bone marrow + endocrine organs phagocytic cells monitor blood at sinusoids

Question 32

capillary bed

Answer 32

capillary plexus connect one arteriole and one venule pre capillary sphincter - guards entrance to each capillary, opens + closes causing capillary blood to flow in pulses thoroughfare channels- direct capillary connections between arterioles + venules

Question 33

venous system

Answer 33

veins collect blood from capillaries and return to heard compared to arteries, have large diameter, thinner walls + lower blood pressure large veins medium veins- less smooth muscle venules- very thin walls, no tunica media or intima smooth muscle present in vein wall allows autonomic control over blood flow and pressure- can vasoconstrict to help with propulsion of blood back to heart

Question 34

valves

Answer 34

fold of tunica intima which prevents blood flowing backward compression of veins pushes blood towards heart when walls of veins near the valves weaken, varicose veins may result

Question 35

skeletal muscle pump

Answer 35

valve opens superior to contracting muscle valve closes inferior to contracting muscle

Question 36

blood flow

Answer 36

total capillary blood flow (cardiac output) = SV x HR determined by pressure and resistance greater resistance = higher pressure (vice versa)

Question 37

pressure

Answer 37

P- generated by the heart to overcome resistance absolute pressure is less important than pressure gradient pressure gradient- difference in pressure from one end of a vessel to the other flow (f) - proportional to the pressure gradient divided by resistance circulatory pressure- must overcome total peripheral resistance total peripheral resistance is affected by vascular resistance, blood viscosity + turbulence

Question 38

vascular resistance

Answer 38

due to friction between blood and vessel walls depends on vessel length and vessel diameter vessel diameter varies by vasodilation + vasoconstriction - R increases exponentially as vessel diameter decreases

Question 39

blood pressure

Answer 39

normal BP= 120/80 systolic/ diastolic hypertension- abnormally high BP (<140/90) hypotension- abnormally low blood pressure

Question 40

redistribution

Answer 40

blood flows to tissue in proportion to their metabolic demands major portion of exercise cardiac output diverts to active muscles increase from 7ml per 100g of muscle at rest to 75ml per 100g of muscle during exercise controlled by regulation of HR

Question 41

regulation of HR

Answer 41

rest- para NS via vagus nerve slows HR by inhibiting SA and AV node symp NS via cardiac accelerator nerves increase HR by stimulating SAN and AVN increase in HR at onset of exercise - initial increase due to parasymp withdrawal

Question 42

changes in stroke volume

Answer 42

increased force of contraction= increased stroke volume how it increases 1. increased sympathetic NS activation- effects of circulating adrenaline + noradrenaline, direct stimulation of heart muscle 2. increased end diastolic volume, leading to increased stretch of sarcomeres and increased force of contraction

Question 43

EDV- end diastolic volume

Answer 43

EDV= amount of blood in ventricles before heart contracts greater EDV= greater stroke volume factors affecting: increased activity of symp nerves to veins increased blood volume increased activity of skeletal muscle pump increased inspiration movements increased venous pressure in peripheral veins, increases venous return + atrial pressure

Question 44

changes in cardiac output

Answer 44

Q increases due to: increased HR increased SV- increases then plateaus at 40% of vo2 max (no plateau if highly trained) cardiac output can increase to 35l/min in highly trained endurance athletes + 20-2l/min in untrained