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Physiology > Lecture 5 - Cardiovascular II > Flashcards

Lecture 5 - Cardiovascular II Flashcards

1
Q

list the vessels returning blood to the heart

A

superior and inferior vena cava, right and left pulmonary vein

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2
Q

list the vessels conveying blood away from the heart

A

pulmonary trunk –> L + R pulmonary arteries, ascending aorta

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3
Q

function of the aorta

A

carries oxygenated blood from the L ventricle to upper and lower body

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4
Q

Function of pulmonary arteries

A

carries deoxy blood from R ventricle to lungs

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5
Q

function of vena cava

A

carries deoxy blood from upper and lower body into R. atria

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6
Q

function of pulmonary veins

A

carries oxygenated blood from the lungs to the left atrium

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7
Q

describe why the brain receives a relatively large portion of blood from the heart compared to other organs

A

needs lots of energy to maintain membrane potential

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8
Q

Describe path of blood flow through the heart starting at the right atrium

A

right atrium –> tricuspid valve –> right ventricle –> pulmonary semilunar valve –> pulmonary arteries –> lungs –> pulmonary veins –> left atrium –> bicuspid valve –> left ventricle –. aortic semilunar valve –> aorta –> systemic circulation –> vena cava –> right atrium

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9
Q

function of superior vs inferior vena cava

A

superior: main route of blood from head, neck and upper limbs to the heart

inferior: main route from lower body to heart

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10
Q

describe the composition of the outer layer of arteries

A

connective tissue

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11
Q

describe the composition of the middle layer of arteries

A

smooth muscle and elastin

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12
Q

describe the diameter and function of elastic arteries

A

large diameter, helps propel blood onward while ventricles are relaxing

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13
Q

describe the diameter and function of muscular arteries

A

medium diameter, capable of greater vasoconstriction and vasodilation, helps adjust blood flow

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14
Q

composition of the inner most layer of arteries

A

thin sheet of endothelium

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15
Q

describe the stretch and recoil pattern of elastic arteries during ventricular systole and diastole

A

stretch during systole (contraction)

recoil during diastole (relaxation of ventricles), propels blood forward

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16
Q

describe the walls of arterioles

A

walls built of smooth muscle rings over elastic tissue

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17
Q

arterioles ______ when smooth muscle relaxes, _____ resistance

arterioles _____ when smooth muscle contracts, ____ resistance

A

dilates, decreasing

constricts, increasing

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18
Q

what do arterioles offer more of, compared to other vessels

A

offer more resistance to blood flow, can significantly affect BP via. vasoconstriction and vasodilation

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19
Q

Describe the walls of capillaries

A

thinnest wall of any blood vessel - consists of endothelial cells, forming a layer one cell thick.

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20
Q

describe the function of capillaries

A

site for diffusion of gasses, nutrients, and wastes between blood and tissues

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21
Q

describe the speed at which blood must flow in the capillaries in order to facilitate exchange

A

blood flow is slowest in the capillaries, must slow down to move substances in and out of the bloodstream

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22
Q

define thoroughfare channel

A

center vessel of capillary beds

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23
Q

what do capillaries branch into

A

capillary beds

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24
Q

function of precappillary sphincters

A

regulates the flow of blood into the capillary, can constrict and restrict blood flow

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25
Q

What are precapillary sphincters made of?

A

ring of smooth muscle

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26
Q

describe blood flow when the pre capillary sphincters are relaxed vs contracted

A

relaxed: blood flows through capillary bed

contacted: blood flows through thoroughfare channel (blood does not flow through capillary bed

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27
Q

do thoroughfare channels have precappillary sphincters

A

naur

28
Q

In the sliding filament model of contraction, explain the state muscles filaments are in when ATP binds, where the ATP binds and the effect it has on both filaments

A

ATP binds to the head of myosin which reduces the affinity of myosin for actin causing the myosin to release from the actin filament. if all cross bridges/muscle were in this state, it would be fully relaxed

29
Q

describe the process of ATP hydrolysis, where it occurs and the effect it has on actin and myosin in the sliding filament model of contraction. What state is the muscle in at this point

A

breakdown of ATP –> ADP and phosphate occurs on the myosin head. (Note: these products stay on the head of the myosin). hydrolysis –> head pivots around hinge (to a 90*C degree angle to the actin and myosin filaments). Rotation causes tip of the myosin to move along the actin filament to line up with a new actin monomer. “cocked state of myosin”, Muscle is relaxed

30
Q

Describe cross-bridging in the sliding filament model of contraction

A

cocked myosin head binds to new actin monomer. ADPPi-myosin complex has an increased affinity for actin

31
Q

what triggers the power-stroke . What happens and what kind of movement is generated

A

release of phosphorous from myosin . myosin head bends about the hinge –> Actin is pulled towards the tail of myosin molecule. Actin filament is drawn along the myosin filament –> generating force and motion

32
Q

what happens when ADP is released from the myosin head in the sliding filament model.

A

actomyosin complex is left in a rigid state (attached state) –> completing cycle. myosin left at a 45 degree angle. complex remains bound until another ATP molecule binds to initiate another cycle

33
Q

Describe how does cardiac muscle contraction is initiated

A

initially tropomyosin is blocking the actin binding sites on the myosin. calcium enters the sarcoplasm (cytoplasm of the muscle cell), binds to cardiac troponin –> moves tropomyosin away from actin binding site exposing where the actin will bind on the myosin. Now myosin head can bind to actin

34
Q

what does smooth muscle use to develop force vs initiate contraction

A

smooth muscle cells use cross bridge to develop force and calcium ions to initiate contraction ( ??????)

35
Q

what does the blood in capillaries flow onwards to

A

venules

36
Q

describe the layers associated with the walls of venules

A

(outward) connective tissue coat, smooth muscle, endothelium (inwards)

37
Q

describe the diameter and function of veins

A

large diameter, low resistance transport of blood back to the heart

38
Q

describe the layers of veins from outer to inner

A

Connective tissue, middle layer of smooth muscle and elastic fibers, inner layer of endothelium

39
Q

function of valves in veins

A

prevent backflow because very low pressure when travelling through veins

40
Q

cause of varicose veins

A

valves dont function properly

41
Q

compare and contrast arteries vs veins describing transport of blood, walls, flow, lumen and presence of valves

A

Arteries: carry blood away from heart under high pressure, thick walls, pulse flow, narrow lumen and no valves

vein: carries blood towards heart under low pressure, thin walls, smooth flow, large lumen and valves are present

42
Q

function of the lymphatic system

A

picks up excess extracellular fluid and usable substances to return them to the cardiovsac. system

43
Q

function of coronary arteries, veins and capillaries

A

hearts own network to supply cardiac muscle cells

44
Q

importance of collateral routes in coronary circulation

A

back up routes so flow doesn’t fully stop, even if major vessels are occluded

45
Q

describe the location of the right and left coronary arteries in terms of where they receive blood and cross

A

exit the ascending aorta just above the aortic valve. 2 branches subdivide and go over surface of the heart as they traverse away from aorta.

46
Q

define Anastomosis and importance in coronary circulation

A

a point where two blood vessels join/merge. Provides collateral (alternative) routes of blood supply to the heart. Ex, branch of L coronary artery joins right branch

47
Q

define oxygen tissue content

A

amount of oxygen available for production of energy to permit body function

48
Q

define myocardial oxygen content

A

balance between how much oxygen is delivered to the heart minus oxygen consumed by the heart

49
Q

what determines how much oxygen is delivered to the myocardium as long as pulmonary function is normal and there is sufficient haemoglobin

A

coronary blood flow

50
Q

what does the amount of oxygen delivered to the heart depend on

A

lung function, haemoglobin present to carry oxygen, how much blood flows through the coronary arteries

51
Q

how do you determine coronary blood flow

A

difference in mean pressure b/w the aorta and the right atrium where coronary blood empties

52
Q

when is coronary flow greatest

A

diastole because it allows for the blood to flow more freely

53
Q

myocardial ischemia

A

imbalance in myocardial oxygen demand and supply

54
Q

what are some of the factors which may contribute to myocardial ischemia

A

increased heart rate (increases o2 consumption as both contraction and relaxation use o2 and decreases time for diastole)

55
Q

describe what the circle of willis is and its importance

A

arterial circle via interconnected vessels in the brain. Large vessels originate from this to supply cerebral cortex. In sp. where circle is complete, blood flow to brain is maintained even with an obstruction at a single point

56
Q

describe cerebral capillaries

A

non- fenestrated capillaries with tight junctions between endothelial cells

57
Q

Describe diffusion and vesicular transport across cerebral capillaries

A

limited diffusion and vesicular transport

58
Q

what are cerebral capillaries surrounded by

A

feet of astrocytes (glial cells)

59
Q

What is the anatomic basis for the BBB

A

Cerebral capillaries

60
Q

What does the BBB help maintain

A

maintains a constant composition of extracellular environment in the CNS

61
Q

Role of the BBB

A
  • protects the brain from endogenous and exogenous toxins
  • prevents the escape of neurotransmitters into general circulation
62
Q

Why are neurological diseases hard to treat

A

BBB limits the penetration of many therapeutic agents into the brain and spinal cord

63
Q

What is the primary role of cerebral spinal fluid

A

protect the brain: serves as a cushion to limit trauma

64
Q

what is cerebral spinal fluid pressure determined by

A

relative rates of formation and drainage

65
Q

What is hydrocephalus

A

presence of excessive accumulation of CSF within the cranial cavity with subsequent dilation of the ventricular system

66
Q

Symptoms of hydrocephalus

A

Head pressing, large dome shaped head, brain dysfunction, abnormal behavior, gait abnormalities

Physiology (52 decks)

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