MTH

Question 1

Explain how an arteriole can reduce blood flow into capillaries.

Answer 1

• muscle contracts
• narrows arteriole

Question 2

Describe how the heart maintains a one-way flow from left atrium to aorta.

Answer 2

• atrium has highER pressure than ventricle
• atrioventricular opens
• ventricle has highER pressure than atrium
• atrioventricular close
• ventricle has highER pressure than aorta
• semilunar opens
• highER pressure in aorta than ventricle
• semilunar close
• contraction causes increase in pressure

Question 3

How does diaphragm movement lead to air in lungs.

Answer 3

• contracts and flattens
• lung volume increase
• pressure inside lungs lower than atmospheric pressure
• air moves in

Question 4

How are lungs adapted to allow oxygen exchange.

Answer 4

• many alveoli so large surface area
• many capillaries so large surface area = fastER diffusion
• thin epithelium = shortER diffusion distance
• ventilation/circulation so maintain conc gradient = fastER diffusion

Question 5

How we breathe in and out.

Answer 5

• trachea, bronchi, bronchioles, alveoli
• breathe IN = Diaphragm contracts, external intercostal muscles contract
• volume increases and pressure decreases in thoracic activity
• breathe OUT = diaphragm relaxes, internal intercostal muscles relax
• volume decrease and pressure increase in thoracic activity

Question 6

Pathway taken by oxygen molecule.

Answer 6

• alveolar epithelium
• endothelium of capillary

Question 7

Why does death of alveolar epithelium cells reduce gas exchange?

Answer 7

• reduced surface area
• increased distance for diffusion
• reduced rate of gas exchange

Question 8

How walls of arteries and arterioles relate to functions.

Answer 8

• elastic tissue stretches under pressure
• recoils
• evens out pressure
• muscle contracts
• diameter of lumen reduced
• changes flow
• epithelium smooth
  -reduces friction

Question 9

Why does wall thickness of aorta change during cycle.

Answer 9

• wall stretches
• pressure increases
• wall recoils
• ventricle relaxes
• maintains smooth flow

Question 10

How to improve quality of scientific drawing.

Answer 10

• single lines/no sketching
• add labels
• add magnification scale
• draw all parts to same scale
• no shading

Question 11

Two precautions when clearing away after dissection.

Answer 11

• carry scalpel around facing down
• disinfect hands with soap
• disinfect surfaces
• put paper towels in a separate bin to dispose

Question 12

How is tissue fluid formed and returned.

Answer 12

Formed=
- high blood pressure
- forces water out
- large proteins remain in capillary

Return =
- low water potential in capillary
- due to proteins
- water enters capillary
- by osmosis

Question 13

SA:V in mammals.

Answer 13

• smallER = greater SA:V
• as more heat loss
• greater rate of respiration
• oxygen required for respiration

Question 14

Coronary heart disease.