3.2 Transport In Animals

Question 1

Describe single and double circulation.

Answer 1

Single - blood flows through the heart once for one complete circulation of the body
Double - blood flows through the heart twice for one complete circulation of the body

Question 2

Why is double circulation more efficient than single circulation?

Answer 2

Ensures oxygenated blood is separated from deoxygenated blood.
Higher pressure on the systemic side ensures materials are delivered further more quickly.
Lower pressure in the pulmonary side reduces chance of damage to capillaries in the lungs.

Question 3

Describe an open circulatory system

Answer 3

There is no separate tissue fluid
Blood circulates around cells and organs
Pressure cannot be raised to help circulation
Circulation is affected by body movements
Oxygenated and deoxygenated blood mix freely

Question 4

Describe closed circulatory systems

Answer 4

Blood is kept in vessels
Pressure can be maintained
Pressure can be higher
Flow faster
Flow can be directed

Question 5

Structure and function of the arteries

Answer 5

Transport blood away from the heart at high pressure.
Thick collagen rich outer layer, thick smooth muscle and elastic fibres, endothelial cells to reduce friction

Question 6

Structure and function of veins

Answer 6

Transport blood back to the heart at lower pressure
Thinner layer of muscle and elastic fibres, thinner collagen outer layer, endothelial cells, valves to prevent backflow of blood.

Question 7

Capillaries

Answer 7

Enable exchange between blood and tissues
Low pressure, one layer of endothelial cells

Question 8

Arterioles

Answer 8

Distribute blood from arteries to capillary bed
Layer of smooth muscle for vasodilation and vasoconstriction

Question 9

Venules

Answer 9

Carry blood from capillary bed to veins
Thin layer of muscle and elastic tissue, thin collagen layer, thin layer of endothelial cells

Question 10

Tissue fluid formation

Answer 10

At the arteriole end, hydrostatic pressure is greater than oncotic pressure so blood plasma is forced out.
Plasma proteins are too large to leave and lower water potential.
Oncotic pressure is greater than hydrostatic pressure at the venule end so re-enter capillary by osmosis

Question 11

Describe blood flow through the heart

Answer 11

Vena cava, right atrium, tricuspid valve, right ventricle, semi lunar valve, pulmonary artery, lungs, pulmonary vein, left atrium, bicuspid valve, left atrium,semi lunar valve, aorta, body

Question 12

What is the function of coronary arteries?

Answer 12

Carry oxygen to the cardiac muscle

Question 13

Describe the cardiac cycle.

Answer 13

Atrial systole: atria contract decreasing volume increasing pressure, AV valves open, blood fills ventricles
Ventricular systole: ventricles contract, AV valves close, SL valves open, blood to arteries
Diastole - heart relaxes. AV valves close, atria fill

Question 14

Cardiac output equation

Answer 14

Cardiac output = heart rate × stroke volume

Question 15

Initiation and coordination of the cardiac cycle

Answer 15

Cardiac muscle is myogenic
SAN - initiates heart beat by stimulating atria to contract
AVN - detects electrical activity from SAN and imposes a delay
Bundle of HIS - receives electrical activity from AVN and conducts to hearts apex
Purkyne - branch off bundles of HIS causing ventricles to contract from base upwards.

Question 16

What does each part of an ECG represent?

Answer 16

P wave - atrial systole
QRS complex - ventricular systole
T wave - diastole

Question 17

What conditions can be shown on an ECG?

Answer 17

Tachycardia - abnormally fast HR
Bradycardia - abnormally slow HR
Ectopic - extra heart beat
Atrial fib - rapid/ ineffective contraction of atria - no clear p wave
V fib - ineffective atrial contraction

Question 18

Describe oxygen transport

Answer 18

Erythrocytes contain Hb which has haem groups
In capillaries in lungs O2 binds to Fe2+ in haem groups forming oxyhaemoglobin
Each Hb can hold 4 O2 molecules
Oxyghaemoglobin is transported to respiring tissues via blood
At body cells O2 dissociates from Hb

Question 19

How is CO2 transported

Answer 19

5% in plasma 85% HCO3- ions 10% combine with Hb = carbaminohaemoglobin

Question 20

Describe CO2 transportation

Answer 20

CO2 diffuses into RBCs and binds with oxygen via carbonic anhydrase forming carbaminohaemoglobin
Carbonic acid dissociates to H+ and HCO3- ions
HCO3- diffuses out of RBC, Cl- ions enter to rebalance charge
H+ binds with Hb to buffer forming haemoglobinic acid
Oxyghaemoglobin must dissociate

Question 21

Why is fetal Hb dissociation curve to the left of adult Hb?

Answer 21

Fetal Hb has a higher affinity for oxygen
Fetal Hb takes up O2 at lower ppO2
Placenta has lower ppO2
At lower ppO2 adult oxyhaemoglobin will dissociate