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Anatomy + Physiology (606) > Cardiovascular System > Flashcards

Cardiovascular System Flashcards

1
Q

functions

A

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

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2
Q

components

A

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

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3
Q

divisions- pulmonary circuit

A

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

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4
Q

systemic circuit

A

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

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5
Q

location of heart

A

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

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6
Q

structure + function of the heart

A

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

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7
Q

valves

A

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

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8
Q

heart wall- pericardium

A

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)

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9
Q

heart wall- myocardium

A

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

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10
Q

intercalated discs

A

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

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11
Q

endocardium

A

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

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12
Q

ventricular differences

A

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

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13
Q

heartbeat

A

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

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14
Q

cardiac cycle

A
  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
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15
Q

heart rate regulation- autonomic NS

A

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

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16
Q

catecholamines- epinephrine

A

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

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17
Q

norepinephrine

A

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

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18
Q

chemoreceptors

A

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

19
Q

barorecpetors

A

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

20
Q

circulatory vessels

A

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

21
Q

distribution of blood volume

A

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%

22
Q

blood vessels

A

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

23
Q

endothelium

A

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

24
Q

tunica intima

A

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

25
Q

tunica media

A

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

26
Q

tunica externa

A

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

27
Q

type of artery

A

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

28
Q

capillary

A

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

29
Q

continuous

A

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)

30
Q

fenestrated capillary

A

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

31
Q

sinusoid

A

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

32
Q

capillary bed

A

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

33
Q

venous system

A

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

34
Q

valves

A

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

35
Q

skeletal muscle pump

A

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

36
Q

blood flow

A

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

37
Q

pressure

A

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

38
Q

vascular resistance

A

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

39
Q

blood pressure

A

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

40
Q

redistribution

A

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

41
Q

regulation of HR

A

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

42
Q

changes in stroke volume

A

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

43
Q

EDV- end diastolic volume

A

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

44
Q

changes in cardiac output

A

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

Anatomy + Physiology (606) (15 decks)

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