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BIO125 Physiology > Week 6 The cardiovascular system (heart & cardiac cycle) > Flashcards

Week 6 The cardiovascular system (heart & cardiac cycle) Flashcards

1
Q

Define the Cardiac Cycle.

A

all evwnts associated with the flow of blood through the heart during single heart beat.

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2
Q

Define a Systole.

A

phase of the cariac cycle in which the heart is contracting

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3
Q

Define a Diastole.

A

phase of the cariac cycle in which the heart is relaxing

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4
Q

What are the features in an Arthropod Heart?

A

They are neurogenic(require external stimulus), humans are the oppostie - homogenic

shape and size VERY variable

Common features:

  • pump hemolymph –> circulation via arteries
  • blood returns to heart via ostia
  • Ostia has valves
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5
Q

Arthropods Hearts: What controls the cardiac cycle?

A

Neurons of the cardiac ganglion needed (found in the surface of the heart, among heart muscle cells)

  • generates rhythm
  • spontaneous rhythmic depolarisations
  • initiate rhythmical contractions of the heart
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6
Q

Arthropod Hearts: the cardiac cycle - how do systole contractions work?

A

systole - contractions:

  • impulses –> heart
  • initiates heart beat and closes ostia

Effects:

  • msucle cells contract
  • ↓ volume in the heart cahmbers
  • ↑ pressure on circulatory fluid
  • blood flows out into circulation
  • + contraction pulls on ligaments
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7
Q

Arthropod Hearts: the cardiac cycle - how do diastole contractions work?

A

diastole - relaxation:

  • cease impulses –> heart
  • suspensory ligaments recoil - elastic recoil outwards
  • pulls apart walls of heart
  • ↓ volume in the heart
  • ↓ pressure on chambers
  • ostia opens
  • ↓ pressure sucks fluid into heart
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8
Q

Arthropods Hearts also act as what?

A

pressure pumps (systole) & suction pumps (diasole)

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9
Q

Vertebrate Hearts: What are 4 distinct layers of the complex walls?

A
  • endothelium (inner)
  • myocardium (middle)
  • epicardium (outer)
  • pericardial sac (visceral & parietal)
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10
Q

Vertebrate Hearts: What is the endothelium layer?

A
  • thin layer of conntective tissue
  • & layer of endothelial cells
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11
Q

Vertebrate Hearts: What is the myocardium layer?

A
  • caridac muscle - cardiomyocyctes
  • divided into several layers
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12
Q

Vertebrate Hearts: What is the epicardium layer?

A
  • thin external membrane
  • continuous with visceral layer of pericardium
  • may contain nerves (depending on heart) - regulates heart & coronary artieries
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13
Q

Vertebrate Hearts: What is the pericardial sac (visceral & perietal) layer?

A
  • double-walled membranous sac (contains fluid)
  • function: lubricates heart, decreasing friction
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14
Q

What is the caridac anatomy of a fish?

A

(water-breathing)

  • 4 chambers
  • blood flow into sinus venousus –> atrium –> ventricle –> bulbous arteriousus
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15
Q

What is the caridac anatomy of an amphibian?

A
  • 3 chambers (2 artria, 1 ventricle)
  • pulmonary vein –> LA
  • sinus venosus –> RA
  • LA & RA –> ventricle
  • conus arteriousus (spinal fold) controls the blood flow going into:
    • systemic arteries
    • pulmocutaneous artery
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16
Q

What is the caridac anatomy of birds & mammals?

A
  • 4 unobstructed chambers
  • Left side: thin walled atrium, thick walled ventricle
  • Right side: thin walled atrium, thin walled ventricle

(ventricles dont have to be symmetric in size, as some preform different functions)

17
Q

Caridac anatomy of birds & mammals: what does the left ventricle do?

A

Left Ventricle: pumps blood to systemic circulation

systemic = high pressure and resistance

–> stronger force of contraction needed

18
Q

Caridac anatomy of birds & mammals: what does the right ventricle do?

A

Right Ventricle: pumps blood to pulmonary circulation

pulmonary = lower pressure and relatively low total resistance

  • large number of capillaries arrnages in parallel
  • shorter distance, shorter vessels
19
Q

Caridac anatomy of birds & mammals: What are the different types of valves?

A
  1. Atrioventricular valves: between atria and ventricles (R = tricuspid valve, L = bicuspid valve)
  2. Outflow valves: pulmonary and aortic (semilunar)

heathy valves have very little resistance - small pressure gradient causes them to open.

20
Q

The structure of the heart:

A
21
Q

What are the considerations of the cardiac cycle:

A

considerations:

  • rhythmic changes in electrical acitivty of the heart
  • alternate periods of contraction (systole) & relaxation (diasole)
  • resultant changes in pressure
    • drice BF (high to low pressure) causing opening/closing of heart valves
22
Q

What are the phases of the cardiac cycle?

A
  1. ventricular filling (during diastole)
  2. isovolumetric contraction (systole)
  3. ventricular ejection (systole)
  4. isovolumetric relaxation (diastole)

Volume stays contstant but pressure changes

23
Q

Define a Stoke volume.

A

the amount of blood ejected by ventricle (SV)

24
Q

Define the cardiac output.

A

volume ejected per minute (SA x heart rate)

the cardiac cycle begins with sinoatrial (SA) node that initiates the heart beat

25
Q

What occurs during Phase 1 of the cardiac cycle?

A

Ventricular Filling

  1. LA pressure higher than LV
    • Mitral valve opens, blood flows into LV
  2. LA contracts - ‘atrial kick’
26
Q

What occurs during Phase 2 of the cardiac cycle?

A

Isovolumetric contraction

​​3. LV contracts

  1. LV pressure rises (Isovolumic contraction)
  2. AV opens when V pressure exceeds A pressure
  3. Ventricular ejection
27
Q

What occurs during Phase 3 of the cardiac cycle?

A

Ventricular ejection

  1. End-systolic pressure falls
  2. LV pressure falls below AP and AV shuts
  3. Period of isovolumic relaxation
  4. LV pressure falls below A pressure and MV opens and V refills
28
Q

What occurs during Phase 4 of the cardiac cycle?

A

Isovolumetric relaxation

​

29
Q

What is the relationship between pressure and volume: P-V Loops?

A

you can relate the phases of the cardiac cycle on the PV loops

30
Q

How can you measure the stroke volume with use of the P-V Loop?

A
31
Q

What phase of the cardiac cycle is systole?

A

isovolumetric contraction & ventricular ejection

32
Q

Arthropod hearts are myogenic. T/F?

A

False. They are neurogenic (require external stimulus), humans are the oppostie - homogenic

33
Q

Arthropod hearts act as a pressure pump during which phase of the cardiac cycle?

A

during systole

34
Q

Is the myocardium of mammals more compact or spongy?

A

more compact

35
Q

How many chambers do amphibian hearts have?

A

3 chambers

36
Q

What are the 2 types of valve that exist in the heart of brids & mammels?

A

Atrioventricular valves & Outflow valves

37
Q
A
38
Q

During isovolumetric contraction in mammals, pressure in the ventricles is greater than pressure in the atria. T/F?

A

True. AV opens when V pressure exceeds A pressure

BIO125 Physiology (17 decks)

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