L09: Special Circulations

Question 1

Where does coronary arteries lie

Answer 1

On the pericardium

Question 2

Which atrium does the coronary veins empty into

Answer 2

Right atrium

Question 3

Which organ has the highest a-vo2 difference

Answer 3

Heart

Question 4

Which organs have the smallest a-vo2 difference

Answer 4

Kidney

Skin

Question 5

Where does the coronary artery originate from

Answer 5

Aorta (just after the aortic valve)

Question 6

Are cardiac muscles highly or low perfused

Answer 6

Highly perfused

Question 7

What adaptation of the cardiac myocytes allow it to have a reduced diffusion distance

Answer 7

High capillary density

Question 8

In the coronary circulation what does haemoglobin hand the oxygen to

Answer 8

Myoglobulin

Question 9

What is the affinity of oxygen to myoglobulin compared to haemoglobin

Answer 9

Higher affinity for oxygen

Question 10

What does myglobulin do to the speed of oxygen transport inside the myocytes

Answer 10

Increase the speed of oxygen transport

Question 11

What mechanism controls the blood flow in coronary circulation

Answer 11

Auto regulation via a myogenic response

Question 12

What other things control the blood flow

Answer 12

Sympathetic innervation
Local factors
Endothelial factors

Question 13

What are local factors

Answer 13

Factors from metabolism

Question 14

List the substances from metabolism

Answer 14

Carbon dioxide
Potassium
Hydrogen ions
Adenosine

Question 15

Which endothelial factors released from blood vessel result in vasodilation

Answer 15

Prostaglandins
Nitric oxide
Endothelial derives hyper-polarisation factors

Question 16

What happens to blood flow in the coronary arteries when they are blocked

Answer 16

Blood flow decreases

Question 17

What happens to the endothelial factors if the blood vessel walls are damaged due to the blockage

Answer 17

Decrease

Question 18

What does reduced blood flow to the coronary circulation result in

Answer 18

Angina (chest pain).

Question 19

Which type of angina is the most serious

Answer 19

Unstable angina (thrombus)

Question 20

What vessels take blood to the brain

Answer 20

2 vertebral arteries

2 carotid arteries

Question 21

What is the circle of Willis

Answer 21

The circle of blood vessel formed when vertebral arteries join to carotid arteries

Question 22

What is the density of the capillaries like in the grey matter

Answer 22

High density

Question 23

What does the high density of capillaries allow in the grey matter

Answer 23

Short diffusion distance for exchange

Question 24

What type of junction does the blood brain barrier have

Answer 24

Tight junctions

Question 25

What controls the blood flow to the brain

Answer 25

Auto regulation via myogenic response

Question 26

What happens to the blood flow to other organs if the brain does not have enough blood flow

Answer 26

Other organs undergo peripheral vasoconstriction to main ABP and cerebral flow

Question 27

What is hypercapnia

Answer 27

High carbon dioxide

Question 28

What is hypocapnia

Answer 28

Vasoconstriction

Question 29

What does hypercapnia do to the blood flow in the cerebral vessel

Answer 29

Increase it by vasodilation

Question 30

What does hypocapnia do to the blood flow in the cerebral vessels

Answer 30

Decrease it via vasoconstriction

Question 31

Are cerebral vessels responsive to levels of arterial oxygen as much as carbon dioxide

Answer 31

No they are less responsive

Question 32

When does cerebral blood flow react to oxygen levels

Answer 32

When there is severe hypoxia

Question 33

What substances does functional hyperaemia result in

Answer 33

Potassium Adenosine Carbon dioxide Hydrogen ions

Question 34

What causes a raised intracranial pressure

Answer 34

Bleeding Cerebral oedema Tumour

Question 35

What happens to cerebral blood flow in postural syncope when you stand up

Answer 35

Cerebral blood flow decreases

Question 36

What are the 2 main functions of the cutaneous circulation

Answer 36

Provide spine with modest metabolic requirements | Regulate body temperature

Question 37

What is the network of cutaneous circulation like

Answer 37

Arteries give rise to arteriole that penetrate dermis to give capillaries Blood flows into the venous plexus Blood from arteries also give blood to venous plexus

Question 38

How does he venous receive blood from the arteries

Answer 38

By arteriovenous anastomoses

Question 39

What is the skin vessel mostly under the influence of

Answer 39

Sympathetic NS

Question 40

What happens to the skin vessel when there is an increased temperature

Answer 40

1) arterioles dilate due to withdrawal of the SNS 2) AVA also dilates and increases blood flow straight into the venous plexus 3) increase in blood to the venous plexus provide a large area of heat exchange between the blood and skin and environment

Question 41

What is the hypothalamic stimulation of the sympathetic fibres innervating the sweat glands

Answer 41

1) sweat glands receive innervation by the sympathetic fibres 2) sweat glands release bradykinin which causes the production of NO 3) this cause vasodilation to the cutaneous vessels and therefore heat loss

Question 42

What happens to the TPR when there is an increase in temperature and vasodilation occurs as a result

Answer 42

TPR decreases

Question 43

What happens to the ABP when TPR decreases

Answer 43

ABP decreases

Question 44

When the ABP falls which reflex detects the change in pressure

Answer 44

The baroreceptor reflex

Question 45

How does the baroreceptor reflex affect the heart

Answer 45

- decreases vagal activity (PNS) and increases SNS activity to the heart to increase HR

Question 46

As a result in an increase HR what happens to the CO

Answer 46

Increase

Question 47

If the CO output increases what happens to the ABP

Answer 47

Increases to normal

Question 48

Therefore as a result of increased temperature how does it affect the heart overall

Answer 48

Tachycardia due to an increased heart rate

Question 49

Describe what happens when there is a drop in temperature

Answer 49

1) SNS activity to the arterioles increase 2) vasoconstriction occurs 3) in addition AVA constricts so there is less blood flow into the venous plexus 4) this minimises heat loss by keeping blood away from the surface

Question 50

In a decreased temperature when skin vessels vasoconstrict where is blood diverted to

Answer 50

Deep vessels that lye beneath insulating fat (interior vessels)

Question 51

What happens to the cutaneous circulation when there is a prolonged exposure to cold

Answer 51

Cold induced vasoconstriction changes to a paradoxical cold vasodilation

Question 52

What does a paradoxical cold vasodilation result in the skin

Answer 52

Red appearance

Question 53

Why do we get a paradoxical cold vasodilation

Answer 53

Paralyses of NA transmission in response to cold

Question 54

How do we transfer heat to the blood returning from the cold periphery

Answer 54

Via a countercurrent exchange

Question 55

What is a Raynaud’s disease

Answer 55

When the skin vessels are overactive due to extreme vasoconstriction when exposed to cold

Question 56

What does the pressure have to be like for blood to flow in a VESSEL

Answer 56

- flow depends on perfusion pressure - artrial pressure is greater than venous pressure and theses 2 pressures have to be greater than the pressure outside (pressure in the ventricles)

Question 57

What does the pressure inside represent

Answer 57

Pressure in aorta

Question 58

What is the pressure outside

Answer 58

Pressure in the ventricles

Question 59

What happens to the flow in the left coronary artery when there is systole of the ventricles

Answer 59

Decrease

Question 60

Why does the coronary artery flow decrease in systole

Answer 60

The pressure outside i.e the ventricles is greater than the pressure in the aorta i.e the coronary artery (pressure inside the VESSELS)

Question 61

What happens when the pressure outside the vessels i.e the ventricles exceed the pressure inside the VESSELS

Answer 61

Extravascular compression in the left ventricular wall

Question 62

What happens to the blood flow during extra vascular compression the left ventricular wall

Answer 62

Coronary blood flow reverse as the myocytes squeeze the coronary vessels

Question 63

What happens to the blood flow in the RIGHT coronary vessels when there is right ventricular contraction

Answer 63

Blood flow will increase

Question 64

Why does the blood flow increase in systole in the RIGHT coronary vessel

Answer 64

The pressure inside the vessel i.e the aorta and therefore the coronary vessel increases greater than the pressure outside the vessel i.e the ventricular pressure

Question 65

By how much does the aortic pressure increase in systole

Answer 65

40 mmhg

Question 66

How much pressure increase is there in the right ventricular pressure in systole

Answer 66

25 mmHG

Question 67

Why does the right ventricular pressure not increase as much as the left ventricular pressure

Answer 67

The right ventricular pressure doesn’t need a lot of pressure to overcome the pulmonary resistance whereas the left ventricular pressure needs a bigger pressure to overcome the systemic resistance

Question 68

At what phase is the left coronary flow the highest

Answer 68

During diastole

Question 69

At what phase is the right coronary artery the highest

Answer 69

During systole