Circulation of blood

Question 1

Functions of CVS

Answer 1

• Bulk of flow of materials
• Temp. regulations
• Homeostasis
• Immune system
• Reproduction

Question 2

Features of CVS

Answer 2

• Heart muscle
• Microcirculation
• Parallel arrangement: allows independent regulation of blood flow

Question 3

• What is the total volume of blood in the body?
• What is the percentage of blood in each of the blood vessels

Answer 3

5 litres

• Pulmonary circulation= 9%
• Systemic circulation 84%
• Heart=7%
• Arteries=13%
• Arterioles and capillaries=7%
• Veins and venules= 64%

Question 4

Characteristics that vary in different blood vessels

Answer 4

• Number
• Diameter
• Wall thickness
• Smooth muscle
• Amount elastic tissue
• Amount of fibrous tissue

Question 5

Diameter of blood vessels

Answer 5

• Aorta= 25mm
• Artery=4 mm
• Arteriole= 0.03mm
• Terminal arteriole=0.01 mm
• Capillary=0.08 mm
• Venule= 0.2 mm
• Vein= 5 mm
• Vena Cava= 30mm

Question 6

State the wall thickness of all of the blood vessels

Answer 6

• Aorta= 2mm
• Artery=0.5 mm
• Arteriole=0.006mm (6 micro-meteres)
• Terminal arteriole= 0.002 mm( 2 micro-metres)
• Capillaries= 0.5 micro-metres
• Venules= 1 micro-metre (0.001 mm)
• Vein= 0.5 mm
• Vena cava= 1.5 mm

Question 7

Blood flow at rest of each major organs

Answer 7

• Brain= 650 mL/min
• Heart=215 mL/min
• Skeletal muscle=1030 mL/min
• Skin=430 mL/min
• Kidneys= 950 mL/min
• Abdominal organs=1200 mL/min
• The rest= 525 mL/min

Question 8

• How many capillaries are there in a body
• Why is parallel arrangement of vessels the best?

Answer 8

• 10 billion capillaries
• It is the best because it allows the independent regulation of blood flow to different organs depending on their metabolic demands. Flow rate and flow distribution can also be independent. E.g while exercising blood flow can go from 5mL/min to 25 mL/min.

Question 8

*Characteristics of AV valves

Answer 8

AV VALVES
* Flimsy
* Passively open
* Attached to chordae tendinae
SL VALVES
* Heavy duty
* Expossed to more stress and physical abrasion due to higher pressure and small opening of vessels

Question 9

Describe the structure of cardiac muscle

Answer 9

• Branched uninucleated cells
• Desmosomes connect them structurally
• Gap junctions link them electrically and allows spread of electrical activity, for functional syncitium (cardiac m. depolarise and contract synchronously).
• Has intercalated discs between cells where desmosomes and gap junctions are located.

Question 10

Autonomic innervation to cardiac muscle

Answer 10

• SNS nerves increase rate of SAN depolarisation
• PSNS decrease rate of SAN depolarisation