week 9 cardiovascular

Question 1

Outline factors that affect mean arterial pressure

Answer 1

Regulation of TPR
cardiac output
regulation of heart rate

Question 2

Discuss intrinsic controls of cardiac output

Answer 2

If ventricular wall stretched before contraction, contractile force increases
If End Diastolic Volume ↑ (meaning the ventricle chamber is stretching and putting pressure on ventricular wall) → SV ↑ → CO ↑

Question 3

Discuss extrinsic controls of cardiac output

Answer 3

Noradrenaline (& adrenaline injection) acting on β1 adrenergic receptors.
Effect: increased contractile force

Question 4

Explain how the autonomic nervous system contributes to the regulation of blood pressure

Answer 4

sympathetic= vasoconstriction and vasodilation// during stress heart rate
parasympathetic= resting heart rate

Question 5

what is autoregulation

Answer 5

local control at the blood vessel site causing immediate localised homeostatic adjustments

Question 6

Neural mechanisms respond quickly to changes (such as sympathetic system):

Answer 6

Cardiovascular centers and vasomotor centre in the medulla oblongata:
Vasomotor center = A cluster of sympathetic neurons in the medulla that oversee changes in blood vessel diameter
Part of the cardiovascular center, and work along with the cardiac centers
Maintains vasomotor tone (moderate constriction of arterioles) receives inputs from baroreceptors, chemoreceptors, and higher brain centers

Question 7

why is autoregulation important

Answer 7

allows body to remain within homeostasis

Question 8

There are two types of chemoreceptors:

Answer 8

1) Peripheral chemoreceptors: present in the carotid and aortic bodies

Highly sensitive to hypoxia
Moderately sensitive to hypercapnia and acidosis
2) Central chemoreceptors: located in the medulla oblongata

Highly sensitive to hypercapnia and acidosis

Question 9

Age-related changes occurring in blood

Answer 9

1) a decrease in total body water -> Decrease in blood volume,
Increased blood viscosity, Sluggish blood flow → more work for heart
2) cellular changes in blood occurs because:

RBC become more rigid, less ‘deformable’:

‘Stiffer’ membranes
More resistance in microcirculation
Impaired oxygen delivery to tissues
3) anemia

Question 10

Age-related changes of blood vessels and flow

Answer 10

1) Arteries become less elastic:

Due to decrease production of elastin protein by fibroblast
Pressure changes can cause aneurysm
2) Increase of calcium deposits on vessel wall → atherosclerosis and increased risk of stroke or infarction

3) Decrease of venous return:

Due to venous valve deterioration
Lack of movement
Dehydration

Question 11

Age-related changes of the heart

Answer 11

1) Changes in heart function and structure:

Reduced maximum cardiac output (in response to exercise or stress)
Cardiomegaly increases, thickening of the left ventricular wall
Decrease of contractility (cardiac cells less efficient to contract)
Changes in conductivity due to:
Reduction of number of pacemaker cells
Increase of fatty and fibrous tissue infiltration of SA node
Increase of scar tissue leading to reduction of heart conduction → heart block → slower heart rate
2) Coronary artery blood flow DECREASES:

Reduction of oxygen delivery to the heart muscle → myocardial hypoxia → myocardial infarction
3) Heat valve changes:

Calcification
Increase Thickness
Decrease valve Flexibility
Incomplete valve closures

Question 12

blood flow through the heart

Answer 12

superior/inferior vena cava
right atrium
tricuspid valve
right ventricle
pulmonary valve
pulmonary arteries
lungs
pulmonary veins
left atrium
bicuspid valve
left ventricle
aortic valve
aorta

Question 13

p waves are associated with what stages in the heart

Answer 13

sinoartial (atria) node depolirization

Question 14

qrs are associated with what stage of blood flow in the heart

Answer 14

depolirzation of the ventricle

Question 15

t waves are associated with what stage of blood flow in the heart

Answer 15

repolirization of the ventricles