Block E Part 1: Blood Pressure, the Heart and Thermoregulation

Question 1

What is the role of the cardiovascular system?

Answer 1

To transport nutrients and other materials, via the blood, to and from various parts of the body
(Lecture 1, Slide 3)

Question 2

How does the cardiovascular system fulfil it’s role?

Answer 2

By continuously circulating blood
(Lecture 1, Slide 3)

Question 3

How does the cardiovascular system continuously pump blood?

Answer 3

The heart acting as a pump
Blood vessels acting as a system of tubes
(Lecture 1, Slide 3)

Question 4

What is blood?

Answer 4

A fluid connective tissue
(Lecture 1, Slide 4)

Question 5

What 4 layers make up the blood?

Answer 5

Plasma
Leucocytes (white blood cells)
Erythrocytes (red blood cells)
Platelets
(Lecture 1, Slide 4)

Question 6

What percentage of total blood volume does plasma make up?

Answer 6

30 - 60%
(Lecture 1, Slide 5)

Question 7

What are 3 things that the plasma layer consists of?

Answer 7

Water
Dissolved organic and inorganic nutrients
Dissolved oxygen
Waste products of metabolism
Hormones
Proteins
pH buffers
(Lecture 1, Slide 5)

Question 8

What does haematocrit mean?

Answer 8

The volume of blood that is composed of red blood cells compared to the total volume of blood
(Lecture 1, Slide 6)

Question 9

What are the values of haematocrit?

Answer 9

40 - 65%
(Lecture 1, Slide 6)

Question 10

Where is the site of gas and nutrient exchange?

Answer 10

Capillaries
(Lecture 1, Slide 7)

Question 11

What is the role of platelets?

Answer 11

Crucial for forming blood clots
(Lecture 1, Slide 7)

Question 12

What can some organs receive that is in excess of their metabolic needs?

Answer 12

Blood
(Lecture 1, Slide 14)

Question 13

Which organ tolerates disrupted blood supply the least?

Answer 13

The brain
(Lecture 1, Slide 14)

Question 14

How long does it take for the brain to sustain irreparable damage when blood supply is disrupted?

Answer 14

4 minutes
(Lecture 1, Slide 14)

Question 15

What is the pressure gradient?

Answer 15

The difference in pressure between the beginning and end of a blood vessel
(Lecture 1, Slide 16)

Question 16

Where does blood flow in terms of pressure?

Answer 16

From an area of high pressure to an area of low pressure
(Lecture 1, Slide 16)

Question 17

Why does pressure drop as the blood flows?

Answer 17

Due to resistance in the blood vessel
(Lecture 1, Slide 16)

Question 18

What is resistance?

Answer 18

A measure of hindrance or opposition to blood flow through a vessel
(Lecture 1, Slide 18)

Question 19

What causes pressure?

Answer 19

Friction between the blood in the vessel wall
(Lecture 1, Slide 18)

Question 20

What happens when resistance to flow increases?

Answer 20

It’s difficult for blood to pass through a vessel, so blood flow decreases
(Lecture 1, Slide 18)

Question 21

What are the 3 main determinants of resistance?

Answer 21

Viscosity of the blood
Length of the blood vessel
Radius of the blood vessel
(Lecture 1, Slide 19)

Question 22

How are venules formed?

Answer 22

When capillaries re-join
(Lecture 1, Slide 21)

Question 23

Why do arteries offer little resistance to blood flow?

Answer 23

Due to their large radius
(Lecture 1, Slide 23)

Question 24

Why do arteries act as a pressure reservoir?

Answer 24

To provide a driving force for blood when the heart is relaxing
(Lecture 1, Slide 23)

Question 25

What 2 types of fibre does arterial connective tissue contain?

Answer 25

Collagen fibres Elastin fibres (Lecture 1, Slide 23)

Question 26

What is systolic pressure and how does it occur?

Answer 26

The peak pressure, occurs when blood is ejected (Lecture 1, Slide 25)

Question 27

What is diastolic pressure and how does it occur?

Answer 27

Minimum pressure - occurs when blood is draining off into vessels downstream (Lecture 1, Slide 25)

Question 28

How is blood flow calculated?

Answer 28

Pressure gradient (ΔP) divided by resistance (Lecture 1, Slide 27)

Question 29

What are 4 factors effecting blood pressure?

Answer 29

Peripheral vascular resistance (diameter of blood vessels) Cardiac output Blood volume Vascular elasticity (Lecture 1, Slide 27)

Question 30

What 2 things can the radius of the arteriole be adjusted to do?

Answer 30

Distribute cardiac output among systemic organs depending on the body's momentary needs Help regulate arterial blood pressure (Lecture 1, Slide 29)

Question 31

What is the internal core temperature?

Answer 31

37°C (Lecture 1, Slide 32)

Question 32

What does the internal core of the body consist of?

Answer 32

Abdominal and thoracic organs Central nervous system Skeletal muscles (Lecture 1, Slide 32)

Question 33

How do tissues function best?

Answer 33

At a relatively constant temperature (Lecture 1, Slide 32)

Question 34

What does the outer shell of the body consist of?

Answer 34

Skin and subcutaneous fat (fat you can pinch) (Lecture 1, Slide 32)

Question 35

What temperature can skin vary between without damage?

Answer 35

20-40°C (Lecture 1, Slide 32)

Question 36

Name 2 things an increase in core temperature can lead to.

Answer 36

Speeds up cellular chemical reactions Overheating (more serious than cooling) Nerve malfunction Irreversible protein denaturation Convulsions (>41°C) (Lecture 1, Slide 33)

Question 37

What 2 things does decreased core temperature lead to?

Answer 37

Slow down in cellular reactions If prolonged and severe, can lead to slowing of metabolism to a fatal level (Lecture 1, Slide 33)

Question 38

What are the 4 mechanisms of heat transfer?

Answer 38

Radiation Conduction Convection Evaporation (Lecture 1, Slide 35)

Question 39

What is the role of the hypothalamus?

Answer 39

Acts as a thermostat - speeds up heat loss or heat production as needed (Lecture 1, Slide 36)

Question 40

What are the 2 ways in which the hypothalamus is activated?

Answer 40

Thermal receptors in the skin provide input to central command Direct stimulation of the hypothalamus through changes in the blood temperature suppling the hypothalamus (Lecture 1, Slide 36)