Mass Transport + Gas Exchange In Humans

Question 1

Explain how the highest blood pressure produced in the left ventricle

Answer 1

Stronger contractions as it has thicker muscular wall

Question 2

Explain the role of the heart in the formation of tissue fluid

Answer 2

Ventricles contract forming high hydrostatic pressure
Which forces water out of the capillaries

Question 3

Describe and explain adaptation of alevolar epithelium

Answer 3

• 1-cell thick, which reduces the diffusion distance , so a increases the rate of diffusion

Question 4

Explain how the constant flow of blood aids gas exchange in the lungs

Answer 4

• maintaining the concentration gradient
• By replacing oxygenated blood with deoxygenated blood

Question 5

Explain and describe how the elastic tissue in the wall helps to even out the pressure of blood flowing
through the artery or during exhalation

Answer 5

stretches as a result of high pressure/surge of blood;
then recoils
Which helps to push air out

Question 6

Apart from lung cancer and other cancers, name 2 other diseases whose risk factors are increased by smoking

Answer 6

•Heart disease
•Diabetes

Question 7

Describe and explain 2 adaptations of alveoli that enable rapid gas exchange

Answer 7

• Large number of alveoli- so that there is an increase in surface area
• Alveolar epithelium is only one cell thick- so there is a reduces diffusion distance, increasing the rate of diffusion
• A large network of capillaries- so that there is a short diffusion distance

Question 8

Describe the pathway taken by a CO2 molecule from the blood to outside the air

Answer 8

•Across the endothelial wall of the capillary
• across the alveolar epithelium into the alveolar space
• It then travels up the bronchioles and up the bronchi
• Into the trachea and out the mouth/nose

Question 9

An oxygen concentration gradient is maintained between the alveoli and the lung capillaries. Describe and explain how this is maintained

Answer 9

• Ventilation brings in air with a high Oxygen concentration
• Circulation removes blood with a high oxygen concentration

Question 10

Explain how the volume of the thorax increases

Answer 10

• external intercostal muscles contract
• diaphragm contracts, moving the rib cage up

Question 11

How are red blood cells adapted to carry oxygen?

Answer 11

• concave shape gives a big surface area for absorbing oxygen. it also helps them pass smoothly through capillaries to reach body cells
• packed with haemoglobin which absorbs oxygen
• they have no nucleus to leave even more room for haemoglobin

Question 12

Explain how the stain allows you to distinguish between white and red blood cells

Answer 12

White blood cells have a nucleus that stains whereas red blood cells do not

Question 13

Suggest how a blockage in the lymphatic system could cause lymphoedema

Answer 13

Excess tissue builds up

Question 14

Explain how cardiac output could stay the same even when their resting heart rate had decreases

Answer 14

Cardiac output= stroke volume x heart rate

Stroke volume increases
Units dm3min-1

Question 15

Effect of flow of blood between aorta and pulmonary artery could cause death

Answer 15

Less oxygenated blood flows through aorta
Less oxygen delivered to cells
Not enough oxygen for aerobic respiration
Tissue doesn’t grow properly

Question 16

Explain four ways in which the structure of the aorta is related to its function

Answer 16

Elastic tissue stretches when ventricles contract to prevent pressure rising to high when blood flows past
Recoils to maintain pressure
Has Muscle for contraction
Thick wall to withstand pressure
Smooth endothelium reduces friction
Aortic valve prevents back flow of blood

Question 17

Species B more active then A. How will the graph show Haemoglobin of B shows greater activity

Answer 17

Curve to the right so LOWER affinity
Haemoglobin dissociates more readily
More oxygen delivered to cells
For faster respiration

Question 18

Explain how an arteriole can reduce the blood flow into capillaries

Answer 18

Muscle contracts
Constricts arteriole
*arteriole short small diamater causes increase in friction decrease in blood pressure

Question 19

Give 2 safety precautions that should be followed when dissecting a heart

Answer 19

Use a sharp scalpel
Cut away from the body
Wash hands

Question 20

Explain how atrioventricular valve maintains a unidirectional flow of blood

Answer 20

Pressure in left atrium higher than in ventricle causing valve to open
Pressure in left ventricle higher than in atrium causing valve to close

Question 21

Deacribe how tissue fluid is formed and how it is returned

Answer 21

High hydrostatic pressure
Forces water out
Large proteins remain in capillary

Return
Lower water potential in capillary due to plasma proteins
Water enters the capillary by osmosis

Question 22

Smokers have loss in elastic tissue

Question 23

Coronary arteries

Answer 23

Branch off the aorta and supply heart muscle w blood

Question 24

Wat is the wall of the heart made of

Answer 24

Cardiac muscle

Question 25

Cardiac cycle

Answer 25

Atria systole Ventricular systole Diastole

Question 26

Risk factors in CHD

Answer 26

High cholesterol diet , high lipid diet, lack of exercise, smoking Leads to High blood pressure increase in cholesterol levels in the blood Leads to Damage to endothelium wall snd increase in lipid uptake

Question 27

Liver blood vessels

Answer 27

Hepatic artery Hepatic vein Hepatic portal vein - takes blood from the intestines to the liver

Question 28

Kidney vessels

Answer 28

Renal artery+ vein

Question 29

What is Mass flow

Answer 29

The bulk movement of liquids and gasses due to a pressure differencd

Question 30

Explain how oxygen in a red blood cell is made available for respiration in active tissues

Answer 30

Increase in Co2 due to increased respiration Increased dissociation of O2 from hameoglobin Low PO2 in tissues Oxygen diffuses from rbc to tissues

Question 31

Describe how HB normally loads in O2 and unloads in tissue cell

Answer 31

Oxygen combines to produce oxyhaemoglobin Each haemoglobin may transport 4 O2 molecules High PO2 in lungs HB fully saturated Presence of CO2 displaces curve to right Causes more O2 to unload as increase in acidity Low PO2 in respiring tissues

Question 32

Describe structure of artery and vein Explain features which help to carry out their functions

Answer 32

Artery has thick wall Allowing it to withstand high pressure Whereas vein has thin wall As does not need to withstand high pressure Both have epithelium (1 cell thick) Consisting of squamous cells Reduces friction with blood Elastic tissue stretches and recoils Maintaining high pressure on blood Veins have valves Which prevent back-flow of blood

Question 33

Explain structures of walls arteries and arterioles

Answer 33

Elastic tissue stretches under pressure Recoils Evens out pressure Muscle contracts Constricts the vessel Changes pressure Smooth epithelium Reduces friction

Question 34

Explain why thickness of aorta wall changes all the time during cardiac cycle

Answer 34

Aorta wall stretches Because pressure in ventricle increases Aorta wall recoils Because ventricle relaxes Maintains smooth flow/pressure

Question 35

Describe and explain how lungs are adapted to allow rapid exchange of oxygen between air in alveoli and blood in capillaries

Answer 35

Many alveoli provide large SA Many capillaries provide large SA So fast diffusion Alveoli one cell thick Squamous epithelium Short diffusion pathway Ventilation+ circulation maintains a diffusion/conc gradient

Question 36

Describe how heart muscle and the valves maintain one way flow of blood from LA to aorta

Answer 36

Atrium has higher pressure in ventricle due to filling of blood Av valve opens Ventricles have higher pressure in atrium Av valve closes Ventricle higher pressure in aorta Semi lunar valve opens Higher pressure in aorta Semi lunar valve closes Muscle contracting increase in pressure

Question 37

Arteriole compared to the artery

Answer 37

Smaller diameter compared to artery so greater friction decreasing blood pressure Thinner elastic layer- lower blood pressure Thicker muscle layer-reduces blood flow into the organ ( to increase O2 delivery to respiring muscle cels for respiration)

Question 38

Describe 2 precautions that student should follow when clearing away after dissection

Answer 38

Wash hands Disinfect instruments

Question 39

Myoglobin dissociation curve

Answer 39

Higher affinity for O2 than Hb Allows aerobic respiration at lowe PO2 Delays anaerobic respiration

Question 40

Myoglobin dissociation curve

Answer 40

Higher affinity to oxygen at lower PO2 Allows aerobic respiration to take place at lower PO2 Delays anaerobic respiration

Question 41

Blood vessel thar carries blood at lowest blood pressure

Answer 41

Vena cava

Question 42

Explain how water from tissue fluid returned to circulatory system

Answer 42

Plasma proteins remain Creates water potential gradient Water moves to blood by osmosis Returns to lymphatic system