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Flashcards in 12 control of cardiac output Deck (30):
1

What is P in an electrocardiogram?

atrial systole

2

What is QRS in an electrocardiogram?

spread of electrical impulses through the ventricles through bundle of his --> purkinje fibres --> ventricular systole and atrial diastole

3

What is T in an electrocardiogram?

ventricular diastole

4

What is QT in an electrocardiogram?

Time between depolarisation if ventricles and relaxation

5

What are the factors effecting cardiac output?

-stroke volume
-heart rate

6

What is cardiac output?

the amount of blood ejected per ventricle per minute

7

What is stroke volume?

volume of blood ejected per ventricle per minute

8

CO of an athlete vs. non athlete

rest: A-5.5 NA - 5
after exercise: A-30 NA-20
L/MIN

9

SV of an athlete vs. non athlete

rest: A-100 NA-65
After exercise: A-165 NA-105

10

HR of an athlete vs. non athlete

Rest: A-55 NA-75
After exercise: A-180 NA-190

11

Heart weight of an athlete vs. non athlete

500 vs 300g

12

What is stroke volume governed by?

-End diastolic volume
-End systolic volume
(mainly diastolic coz what enters the heart must leave the heart)

13

How is the heart rate slowed down?

The vaygus nerve which acts on the SAN and releases acetylcholine

14

How is the heart rate increased?

The accelerator nerve which acts on the SAN and releases norepinephrine/noradrenaline

15

What is a positive chonotropic effect?

Increases the heart rate

16

Name 4 things that have a positive chonotropic effect on the heart

-norepinephrine
-adrenaline
-glucagon
-thyroid hormones

17

What part of the brain is responsible for the heart

pons?

18

where does adrenaline/ noradrenaline come from?

Adrenal gland
sympathetic nerves
kidneys

19

How do positive chonotopic substances work?

they cause a faster inflow of sodium and calcium ions which causes the threshold to be reached much faster.
reduced repolarisation (below the line) so there can be more depolarisation

20

How does acetylcholine work on the heart?

It causes K to leave the cell faster and so causes slower depolarisation. its all about what happens before threshold potential is reached - after that its all the same
-the membrane becomes more hyper polarised
acts on the muscarininc K channels (more neg)

21

What is the HR if you cut the vaygus nerve?

110

22

What happens to HR if you inhibit ACH

it increases from 70 to 110

23

What is fast heart rate called?

Tachycardia

24

What is a slow heart rate called?

Bradycardia

25

Why do some people have a lower heart rate? (e.g. athletes)

Increased vaygal tone --> more ACH acting on SAN

26

What is the the preload?

The pressure exerted on the ventricles by the filling of blood. can be measured using the EDV. the amount of blood entering the ventricles/atria

27

How do you work out stroke volume?

EDV-ESV

28

What is the afterload?

the end load against which the heart contracts to eject blood from the ventricles

29

What effects the afterload

-preload volume
-aortic pressure (^=^)
-vasoconstriction

30

What is contractility?

The energy of contraction regulated by SNS and adrenaline