Introduction to the Cardiovascular System (1.0)

Question 1

Why do we need a CV system?

Answer 1

Distance of cells from the source of O2 and metabolic substrates is too far.

DIFFUSION works well over short distances. Diffusion takes too long over larger distances

Question 2

What are the components of the CVS?

Answer 2

Distribution System: Vessels and Blood

Pump: Heart

Exchange Mechanism: Capillaries

Flow Control: Arterioles and Pre-capillary sphnicters

Question 3

Explain the structure of capillaries and how they are adapted to exchange for different molecules

Answer 3

Capillaries are composed of single layer of endothelial cells surrounded by BASAL LAMINA

O2 and CO2 can easily diffuse through the lipid bilayer. Other molecules, such as glucose, amino acids and lactate are HYDROPHILIC and diffuse through small aquous pores in the capillaries

Question 4

What effects the Rate of Diffusion?

Answer 4

Area (depends on the CAPILLARY DENSITY - a tissue that is more metabolically active will have more capillaries)

Diffusion Resistannce (nature of molecule, nature of the barrier and diffusion distance)

Concentration Gradient (greater the concentration gradient, the greater rate of diffusion

Question 5

What influences the change of substrate concentration between arterial and venous ends?

Answer 5

The rate tissues use the substance

The rate of blood flow through the capillary end

Question 6

What is PERFUSION RATE?

Answer 6

The rate of blood flow

Question 7

Explain the blood flow to the:

• Brain
• Heart
• Kidneys
• Skeletal Muscle/Gut

Answer 7

BRAIN: needs constant high flow of 0.5ml.min-1.g-1

HEART: high flow which increases during exercise of 0.9-3.6ml.min-1.g-1

KIDNEYS: needs high constant flow of 3.5ml.min-1.g-1

SKELETAL MUSCLE: high during exercise annd gut blood flow is high after a meal

Question 8

At REST, total blood flow is around _______ l/min-1

During EXERCISE, total blood flow can rise to _____ l/min-1

Answer 8

5

25

Question 9

What organ is the hardest to perfuse and why?

Answer 9

Brain - it is against the force of gravity

Question 10

How is blood flow regulated?

Answer 10

Via RESISTANCE vessels known as ARTERIOLES

They allow flow of blood to be re-directed to move to more diffifcult areas to perfuse (such as the brain)

Question 11

The heart consists of two pumps in series - what are the features of this circulatory systems?

Answer 11

Double Circulatory System

Closed Circulatory System

Question 12

Where is TEMPORARY BLOOD stored? - What is this known as?

Why is this storage important?

Answer 12

VEINS have thin walls (which can DISTEND and COLLAPSE) that allows them to store blood. Therefore, each vein has CAPACITANCE: the ability to store charge

Storage of blood in the CVS is important to allow the system to respond to increase demands during exercise

Question 13

Where does most blood reside?

Answer 13

Within the veins