Transport in Animals

Question 1

Mammals and fish both need circulatory systems to transport oxygen to respiring tissues. They have different circulatory systems because they have different oxygen requirements.

Compare and contrast the circulatory systems of mammals and fish

Answer 1

Similarities:
- Both have a heart
- both carry oxygen by haemoglobin
- both carry blood in veins, arteries and capillaries
- both have a closed circulatory system

Differences
F = blood passes through 2 sets of capillaries BUT
M = blood passes through 1 set of capillaries before returning to the heart
F = blood pressure is low to organs BUT
M = blood is maintained at higher pressure
F = lower oxygen demand - controls internal temp by other means - lower metabolic rate
M = mammals need to maintain their own internal body temp with metabolic activity and have a high metabolic demand
F = have a single circulatory system
M = double circulatory system

Question 2

Compare the circulations of a frog and a mammal and the relative effectiveness of each type of circulation.

Answer 2

Circulations:
- Both are double circulations
- blood from mammalian is transported separately to the lungs and the body
- oxygenated and deoxygenated blood never mix
- blood carries oxygenated and deoxygenated blood together in frogs - partially oxygenated
- oxygenated blood is only separate when reentering the heart
- blood flows through the atriums and ventricles and out through arteries
- there is no septum in frog heart and no valves whereas there are both in mammals

Effectiveness of circulation:
- both deemed to be effective at providing O2 for their own metabolic demand
- frog considered less effective - less O2 available for body cells
- frog has a lower metabolic rate than mammals so circulation effective
- frogs heart may beat faster to compensate
- mammals body cells get maximum O2 to cells
- mammals have higher metabolic rate
- mammals maintain their own body temp using metabolism

Question 3

Outline how the differences in lumen size between arteries and veins is related to their function. (3)

Answer 3

In arteries the lumen maintains pressure
In veins low resistance is needed because of the slow flow rate
The same flow rate is achieved by there being a larger cross sectional area so fewer particles colliding with the wall ( lower resistance)

Question 4

A student cut her hand on a school trip. The bleeding stopped and formed a scab. However over the next. 3 days, the area around the cut became swollen, red and tender. They also noted a small swelling and discomfort around the armpit.

Describe the non - specific defences against pathogens that would explain all of these observations.

Answer 4

Bleeding stops:
- exposure of platelets to collagen activates blood clotting cascade
- soluble fibrinogen converted to insoluble fibres
- mesh of fibrin traps cells and platelets
- clot dries out to produce a scab
- scab prevents entry of pathogens

Swelling/redness:
- infection by pathogens
- detection by mast cells
- release of histamines causes arterials to vasodilate
- more tissue fluid forms causing more swelling ( oedema )
- phagocytes attracted to the area
- phagocytosis of pathogens

Discomfort in armpits :
- excess tissue fluid drained to lymph vessels
- pathogen in tissue fluid enters lymph fluid
- pathogens transported along lymph system
- phagocytes cause swelling of lymph nodes / armpit discomfort

Question 5

Describe similarities and differences between ultrafiltration and formation of tissue fluid.

Answer 5

Similarities:
- small molecules are filtered / diffuse out of the cell
- both processes occur in capillaries
- large molecules remain in the blood
- high hydrostatic pressure in both
- many molecules are reabsorbed back Into the blood
- blood vessels become narrower to maintain high hydrostatic pressure
- hydrostatic pressure greater that oncotic pressure in both
- both involve basement membranes

Differences:
- filtrate enters bowman’s capsule and PCT whereas TF bathes cells
- molecules that are not reabsorbed into the blood form urine / molecules not absorbed are drained into the lymph nodes
- blood filtered through 3 layers in ultrafiltration ,but only 1 layer in formation of tissue fluid
- knot of capillaries in ultrafiltration / network in tissue fluid formation

Question 6

Describe the cardiac cycle.

Answer 6

Atrial systole;
Atrial contracts
Pressure in the atrial increases
Blood flows through the atrioventricular valves
Ventricles fill with blood and pressure in the ventricles increase and pressure in the arteries are low

Ventricular systole
Ventricles contract
Volume of the ventricles decreases
Pressure in the blood increases
Atrioventricular valves close
Semis lunar valves open
Blood flows into aorta/PA

Diastole
Atria relaxes
Ventricles relaxed
Blood flows through the AVV
Blood enters the atria passively
Blood enters ventricles passively

Question 7

What are the units for cardiac output

Answer 7

Cm^3 min^-1

Question 8

What are the features of bradycardia ECG

Answer 8

Lower QRS complex
Width of the T wave greater
Slower heart beat

Question 9

What are the defining features of ectopic heartbeat.

Answer 9

Early contraction of the atrium
P wave comes earlier than it should

Question 10

What are the defining features of fibrillation

Answer 10

Atria and ventricles completely lose their rhythm completely and stop contracting properly
Distorted QRS complex
No defined P waves