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CELL BIOLOGY AND PHYSIOLOGY > week 7+8 - cardiovascular system > Flashcards

week 7+8 - cardiovascular system Flashcards

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1
Q

historic view of the cardiovascular system
ancient greece

A

400BC to 300BC

nutrients are carried around the body
heart at centre
differences noted between arteries and veins

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2
Q

historic view of the cardiovascular system
Galen

A

130AD

arteries contains blood

ventricles pulsate, veins do not

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3
Q

historic view of the cardiovascular system
leonardo Da Vinci

A

1400s

the heart is a muscle
atria identified as chambers
first description of atheroscieotoic coronary arteries

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4
Q

historic view of the cardiovascular system
Realdo Colombo

A

1500s

pulmonary vein is full of blood, not air
valves stop blood returning to lungs from heart
venous return

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5
Q

historic view of the cardiovascular system
ceasare cermoni

A

arteries involved in transport of nutrition (quantity)

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6
Q

historic view of the cardiovascular system
william harvet

A

arteries and veins contain the same blood
arteries recieve blood from veins via the heart
valves prevent blood travelling backeards in veins

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7
Q

structure of the heart

A

Heart is found in the mediastinum between the lungs and between the sternum and the vertebral column

Slightly more towards the front of the body

Roughly the size of your closed fist

Average mass
Women- 250g
Men - 300g

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8
Q

heart: key facts

A
  • Roughly the size of your closed fist
  • Average mass: 250g (W), 300g (M)
  • Found in mediastinum (between lungs and between sternum to vertebral column)
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9
Q

heart:
Pericardium
function

A

the heart is enclosed and the pericardium holds it in place (protection)

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10
Q

heart:
Pericardium
structure

A

fluid filled sac

consists of an outer fibrous layer and an inner serous layer

inner serous layer has two different layers
- visceral
- parietal
these layers are seperates by the serous cavity

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11
Q

layers of the heart wall:

A
  1. epicardium
  2. myocardium
  3. endocardium
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12
Q

layers of the heart wall:
epicardium

A

The outermost layer of the cell if forced of the visceral layer of the serous pericardium
This is where the pericardium adheres to the heart

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13
Q

layers of the heart wall:
myocardium

A

Cardiac muscle tissue
Responsible for the pumping action of the heart
Forms cardiac muscle fibres

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14
Q

layers of the heart wall:
endocardium

A

Innermost layer
Really smooth layer inside to minimize the friction for the blood that’s passing through

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15
Q

layers of the heart wall:
fibrous pericardium

A

bag
prevents over stretching
apex fused to diaphragm

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16
Q

layers of the heart wall:
parietal layer of serous pericardium

A

thinner than FP and more delicate
double layer
parietal (outer) layer fused to FP

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17
Q

heart valves
why?

A

o Separates the atria and the ventricles
o And atria and ventricles to the rest of the body

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18
Q

chambers of the heart

A
  • The chambers of the heart include two upper atria and two lower ventricles
19
Q

what do the heart valves do

A
  • They initiate cardiac excitation
  • They conduct action potential along the ventricle
  • They strengthen cardiac contractions
    o When closed allow for the pressure to build up
  • They ensure that blood only flows in a single direction.
20
Q

where are the valves in the heart

A
  • Atrioventricular valves
    o separate atria from ventricles
  • Semilunar valve
    o Ventricles to arteries away from heart
21
Q

heart valves and circulation of blood

A
  • The valves of the heart open and close in response to pressure changes as the heart contracts and relaxes
    o Right and left atrioventricular valves
     Prevent back flow from the ventricular into the atria
    o Right and left semilunar valves
     Prevent back flow from the arteries into the ventricles
22
Q

heart valves and circulation

A
  • When one set valves is open, the other set is closed
    When semilunar valves are closed blood goes from your atria to ventricles
    When semilunar valves are open blood goes from ventricles to the rest of the body
23
Q

what happens when the heart valves are damaged

A
  • Blood flow around the heart is restricted
  • Valve stenosis:
    o Valve wont open properly
    o Blood flow restricted
    o Heart has to pump harder to force blood through the narrow gap
  • Valve incompetence or regurgitation
    o Valve wont close properly
    o Blood leaks backwards
    o Heart has to work harder to pump the required volume of blood through the heart
24
Q

cardiovascular system process:

A
  1. sinoatrial node
  2. AV node
  3. bundle of His
  4. right and left bundle branches
  5. purkinje fibres
25
Q

cardiovascular system process:
1. sinoatrial node

A

Autorhythmic fibres
- Self excitable
- Generate action potenials that cause heart contraction
Need to be an action potential generates in heart

1st step
Generation of action potential through autorhythmic fibres through the Sino atrial node
Self excitable (always firing)
Don’t have to think about it
No stable resting potential
When threshold reaches –> action potential
* Happens every 0.6 seconds
* The rate of firing can be altered by nervous impulses from the automimic nervous system and hormones in the blood

26
Q

cardiovascular system process:
2. atrioventricular (AV) node

A
  • 2nd step
  • This impulse if conducted along the atrio ventricular fibres and the AV node slows down the action potential allowing time for the atria to empty the blood into the ventricles
27
Q

cardiovascular system process:
3. atrioventricular (AV) Bundle of His

A
  • Third step
  • The atrio ventricular bundles and the bundle of his is the only site where action potential is conducted from the atria to the ventricles because the other parts of your heart are insulated by fiber skeletal muscle
28
Q

cardiovascular system process:
4. Right and left bundle branches

A
  • 4th step
  • There are both left and right bundle branches
  • Which extend through the septum
  • so all the way down and up towards the apex the heart
  • and the action potential can enter both the left and right sides of this
29
Q

cardiovascular system process:
5. purkinje fibres

A
  • 5th step
  • The purkinje fibres are responsible for conducting the action potential apex up to the ventricle myocardial towards the semi lunar valves before the blood is finally ejected
30
Q

cardiovascular system process:
how does this correlate to an ECG?

A

An electrocardiogram

Basically a trace showing how your heart is functioning
The different parts of ECG show different things which we can relate back to the structure of the heart

31
Q

electrocardiogram

A
  1. depolarisation of atrial contractile fibres produces P wave
  2. atrial systole (contraction)
  3. depolarisation of ventricular contractile fibres produces QRS complex
  4. ventricular systole (contraction)
  5. repolarization of ventricular contractile fibres produces T wave
  6. ventricular diastole (relaxation)
32
Q

electrocardiogram
1. depolarisation of atrial contractile fibres produces P wave

A
  • Cardiac action potential from SA node
  • AP propagated through atrial muscle down AV node
  • Atrial contractile fibres depolarize
33
Q

electrocardiogram
2. Atrial systole

A
  • Atria contract (atrial systole)
  • AP conducted to AV node (SLOW)
  • Blood enters ventricle before ventricular systole
34
Q

electrocardiogram
3. depolarization of ventricular contractile fibres produces QRS complex

A
  • Enter AVB bundle
  • AP rapid propagation
  • P: bundle branches, Purkinje fibres, ventricular myocardium
  • QRS: septum, up from apex, out from endocardial surface
  • At this time, atrial repolarization but cant see as hidden by PQRS
35
Q

electrocardiogram
4. ventricular systole (contraction)

A
  • Ventricular contralice fibres contract (ventricular systole)
  • Soon after QRS and during S-T segment
  • Blood squeezed upwards towards semilunar valves
    left side ejected to aorta
    Right side ejected ot pulmonary trunk
36
Q

electrocardiogram
5. repolarization of ventricular contractile fibres produce T wave

A
  • Repolarization apex through ventricular myocardium
  • ~0.4sec after P wave begins
    o When ventricles start to relax and the pressure falls
37
Q

electrocardiogram
6. ventricular diastole (relaxation)

A
  • Ventricle starts to relax (ventricular diastole)
  • By 0.6sec, ventricular repolarization completed
38
Q

Molecular overview of AP in ventricular contractile fibres (QRS)

A
  1. rapid depolarization due to Na+ inflow when voltage gates fast Na+ channels open
  2. Plateau (maintained depolarization) due to Ca2+ inflow when voltage-gated slow Ca2+ channels open and K+ outflow when some K+ channels open
  3. repolarization due to closure of Ca2+ channels and K+ outflow when additional voltage-gates K+ channels open
39
Q

summary
heart function is…

A

difficult to determine by anatomy alone

40
Q

summary
the heart has…

A

4 chambers made of several layers of tissue

41
Q

summary
the heart functions to:

A

pump blood around the body using self-propagating action potentials

42
Q

summary:
the actions of the heart can be analysed using a…

A

ECG

43
Q
A

CELL BIOLOGY AND PHYSIOLOGY (11 decks)

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