Module 1 Lecture 4

Question 1

Label the diagram on blood pressure throughout circulation!

Answer 1

–

Question 2

What does blood pressure gradient do?

Answer 2

the blood pressure gradient keeps blood flowing from high to low

Question 3

What is blood pressure depended on?

Answer 3

- the volume of blood and the compliance of vessel, Fluctuates
throughout the
systemic
circulation &
during the cardiac
cycle

Question 4

What is systolic pressure?

Answer 4

– Systolic pressure is the max
pressure in arteries when blood
is pumped into them

Question 5

What is diastolic pressure? what is the diagram yo?!

Answer 5

Diastolic pressure is the min
pressure in arteries when there
is no heart contraction & blood
continues to flow into arterioles

Question 6

What is pulse pressure?

Answer 6

Pulse pressure is the difference
between systolic & diastolic
pressures. It is this pressure
difference we can feel when
taking our pulse

Question 7

What is mean arterial pressure?

Answer 7

Mean arterial pressure is
the average pressure during
each cardiac cycle. This is
the pressure that the body
monitors & regulates

Question 8

What is MAP

Answer 8

MAP = diastolic pressure + 1/3 (systolic – diastolic)

MAP is the average pressure during each cardiac cycle

Question 9

What is MAP’s Main purpose?

Answer 9

The main purpose of MAP is to drive blood into tissues

Question 10

Blood flow to organs depends on what?

Answer 10

Blood flow to any given organ depends on:
1. resistance of local arterioles
2. vascularisation/open capillaries
MAP is the driving pressure head

Question 11

Driving pressure head in arteries diagram, explain!

Question 12

Why must MAP be closely monitored and regulated?

Answer 12

MAP must be closely monitored & regulated to ensure:
1. high enough for sufficient drive, despite local
adjustments
2. low enough to avoid damage to heart & blood
vessels

Question 13

What are the 2 determinants of MAP?

Answer 13

Regulation occurs through the integration of elaborate
mechanisms, involving various aspects of the body. The
two determinants of MAP are:
MAP = CO x TPR

Question 14

NOTE DIAGRAM

Answer 14

A change in any factor will change MAP unless another factor changes to compensate for it

Question 15

When MAP deviates from a normal ‘set-point’ numerous

responses are initiated, what are they?

Answer 15

Short-term: autonomic nervous system to heart,
veins, & arterioles as well as hormones -> CO & TPR
- Long-term: kidney & thirst responses to regulate
total blood volume -> CO

Question 16

What are baroreceptors and where are they located?

Answer 16

Short-term: autonomic nervous system to heart,
veins, & arterioles as well as hormones à CO & TPR
- Long-term: kidney & thirst responses to regulate
total blood volume à CO

Question 17

How does Baroreceptors reflex regulates short-term responses in MAP

Answer 17

-Baroreceptors fire action potentials in response to
pressure in these arteries
– Impulses are delivered via afferent neurons to the
cardiovascular control centre in medulla of brain
stem, where information is integrated
– Sympathetic & parasympathetic outflow via efferent
neurons are adjusted
– Heart & blood vessels change their status to restore
MAP

Question 18

Describe the journey where changes in blood pressure occur

Answer 18

–

Question 19

What are the 2 long-term regulation of MAP?

Answer 19

Left atrial volume receptors and Hypothalamic osmorecepters

Question 20

What are left atrial volume receptors?

Answer 20

Left atrial volume receptors: detect a profound fall in
blood volume/pressure. Stimulates hypothalamus to
release ADH from posterior pituitary -> targets kidneys to
reabsorb water (↑ blood volume) & arterioles to cause
vasoconstriction (↑ TPR)

Question 21

What are hypothalamic osmoreceptrs?

Answer 21

Hypothalamic osmoreceptors: detect a rise is ECF
concentration (e.g. dehydration) à stimulates thirst
responses (↑ fluid intake, ↑ blood volume)

Question 22

What happens in the cardiovascular system under stress (exercise)

Answer 22

Marked changes occur in anticipation & at
onset of exercise:
• CO ↑ ~3-5-fold with moderate to heavy
exercise
• CO is re-distributed compared to rest:
- Skeletal muscle, cardiac muscle & skin receive a ↑ proportion
- Other organs receive ↓ blood flow, but brain is maintained
• TPR reduced due to widespread vasodilation in skeletal muscle
• MAP modestly increased

Question 23

Hypertension? p1

Answer 23

Hypertension > 140/90 mmHg
• Two broad types:
- Secondary: known cause &
accounts for 10% of cases, e.g.
kidney disease
- Primary/Essential: unknown cause, accounts
for 90% of cases, e.g. genetic, exacerbated by
environmental factors
• Vicious cycle: damages vessel walls,
atherosclerosis - increased TPR - further
elevates BP

Question 24

HypERtension? p2

Answer 24

Baroreceptors do not return blood pressure back to
normal levels à new set-point?
• Increased workload on heart as it is now
pumping against an increased pressure
Complications:
- Left ventricular hypertrophy -> systolic heart
failure
- Stroke (rupture of cerebral vessels)
- Myocardial infarction (rupture of coronary
vessels)
- Kidney failure
- Vision loss

Question 25

Hypotension

Answer 25

heart
• Orthostatic (postural) hypotension: transient inadequacy in
sympathetic activity
– Lying to standing à blood pools in lower leg veins -
reduced venous return - reduced SV, CO & MAP -
reduced baroreceptor response à dizziness or fainting
• Circulatory shock: extremely low blood pressure such that
blood flow to tissues is compromised. Causes: hypovolemic
shock, cardiogenic shock, vasogenic shock, & neurogenic
shock