Physiology of the Heart Flashcards Preview

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Flashcards in Physiology of the Heart Deck (238)
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1

List the transportation roles of the heart and circulation

Transporting:

  • Vitamins
  • Nutrients
  • Oxygen/CO2
  • Hormones
  • Immunoglobulins
  • RBC/WBCs

2

Give the thermoregulatory roles of the heart and circulation

  • Counter-current exchange mechanism
  • Circulation of the skin

3

Give the 3 major parts of the circulation

  • Heart
  • Systemic circulation
  • Lung circulation

4

Describe Starling's effect

To increase load, the heart automatically reacts with extra work

without hormonal/neuronal factors

5

Describe the heart's work load status during rest

The heart is working in the lower range of its total working capacities

This is ensured by parasympathetic predominance

6

A decrease of parasympathetic activity may cause...

An increase in the mechanical performance of the heart

7

The autonomity of the heart rythmn is due to...

Rythmn generators in the SA node

8

Give the main parameter of cardiac mechanical performance

Cardiac output

The volume of blood propelled into the aorta from the left ventricle per unit time

9

List the layers of the heart

  • Endocardium
  • Myocardium
  • Epicardium
  • Pericardium

10

Give the contractile components of the myocardium

  • Heart muscle fibres (working fibres)
    • Stretching enhances their force-generating capability

11

Give the non-contractile components of the myocardium

  • Serially attached elastic elements (SEC)
  • Parallelly attached elastic elements (PEC)
  • Collagen

12

List the functions of the pericardium

  • Fixation: keeps the heart in the mediastinum
  • Protection from infection from other organs
  • Prevents excessive dilation of the heart during hypervolemia
  • Lubricates the heart

13

Describe fetal circulation in relation to the pulmonary circulation

  • Lungs not functioning
    • Blood bypasses lungs foramen ovale
    • Between L & R atrium

14

Describe the closing of foramen ovale 

  1. Pressure in left atrium increases
  2. Flap valve covers foramen ovale
  3. After 1 year, the foramen completely closes
  4. It is then regarded as fossa ovalis

15

  • What percentage of the population does the foramen ovale not seal?
  • What is the condition called?

  • 30%
  • Patent foramen ovale (PFO)

16

 Name the fetal vessel between a. aorta thoracica and a. pulmonalis

Ductus botallo

17

When does ductus botallo close?

4 weeks postpartum

18

List the excitable varieties of cardiac tissue

  • Pacemakers
  • Conductive system
  • Working fibres

19

Purpose of the Aschoff-Tawara (AV) node

Delays the atrial signal

So atrial contraction precedes the ventricular contraction

20

Resting membrane potential (RMP)

Diastole:

  • -90mV
  • Spontaneous depolarisation followed by AP
  • RMP doesn't exist in pacemaker cells

 

21

Describe action potential (AP)

  1. Stimulation
  2. Ion channels of membrane open
  3. Ion exchange between the two sides
  4. Action potential

22

Pacemaker potentials

23

Pacemaker cells

  • Located: SA / AV node
  • Allow continuous generation of excitation
  • No RMP
  • Repolarisation: Transmembrane potential -55mV
  • Automatic depolarisation follows

24

This electrical activity is expressed in...

Sinoatrial (SA) node

25

This electrical activity is expressed in...

Ventricular muscle

26

Pacemaker action potential is...

  • Slower/faster

and

  • Lower/higher

...than cardiomyocytes

  • Slower
  • Lower

27

Round pacemaker cells

Sites of the generation of excitation

28

Elongated/slender cells

Conduct/synchronise excitation generated in round pacemaker cells

29

Maximal depolarisation potential (MDP)

No RMP developed after the previous AP reaches -55mV

30

  • K+ channels close
  • Na+ channels open