mass transport in humans Flashcards

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1
Q

describe the double circulatory system in mammals?

A
  • blood passes through heart & gets pumped to the lungs, returning back to the heart (pulmonary circulation).
  • The blood now passes through heart 2nd time (blood is re-pressurised) & pumped round the body organs before returning to the heart (systemic circulation).
  • Blood moves around the body due to pressure difference between the pressure in the heart (high) and pressure in the blood vessels (low). This is mass flow.
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2
Q

describe the heart structure?

A

2 pumps, w upper chamber(atrium) & lower chamber (ventricle). heart wall made of cardiac muscle. (heart cells = cardiomyocytes)
1. Deoxygenated blood returns from the body via vena cava (vein) and enters right atrium
2. The blood then passes, via an atrio-ventricular valve into the right ventricle and out, via the semi-lunar valve, into the pulmonary artery.
3. The blood now passes through the lungs and returns to the left atrium via the pulmonary vein.
4. The blood passes through 2nd atrio-ventricular valve into left ventricle and then through semi-lunar valve into aorta, then onto the body tissues

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3
Q

Describe how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the aorta.

A
  1. Atrium has higher pressure than ventricle (due to filling / contraction);
  2. Atrioventricular valve opens;
  3. Ventricle has higher pressure than atrium (due to filling / contraction);
  4. Atrioventricular valve closes;
  5. Ventricle has higher pressure than aorta;
    Points 1, 3, 5, and 7 must be comparative: eg higher
  6. Semilunar valve opens;
    Marks 2, 4, 6, 8 given in the correct sequence can gain 4 marks
  7. Higher pressure in aorta than ventricle (as heart relaxes);
  8. Semilunar valve closes;
  9. (Muscle / atrial / ventricular) contraction causes increase in pressure;
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4
Q

what is systole and diastole?

A

systole - contraction of heart muscle
diastole - heart muscle relaxed

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5
Q

what causes a change of pressure in the heart chambers?

A

changes in volumes of blood in chambers and contractions of heart muscle

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6
Q

Explain how an arteriole can reduce the blood flow into capillaries.

A
  1. Muscle contracts;
  2. Constricts/narrows arteriole/lumen;
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7
Q

what is cardiac output and how is it calculated?

A
  • volume of blood expelled from left ventricle per minute
    cardiac output = stroke volume x heart rate(BPM)
    SV: volume of blood expelled from left vent. in 1 cardiac cycle
    units: dm3 min-1
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8
Q

what are the 2 most common causes of blockage to coronary arteries (heart disease) and what can be the outcome?

A
  • atherosclerosis (atheroma formation - fatty deposits in lumen of artery - leads to heart attack)
  • thrombosis (plaque ruptures & causes blood clotting - leads to stroke)

aneurysm : artery blocked, blood flow restricted, blood pressure build up and weaken wall. start to bulge outwards. may rupture & cause internal bleeding

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9
Q

what are the risk factors of coronary heart disease and what can this lead to?

A
  1. age - gradual deposit over time
  2. gender - men more risk until women menopause (oestrogen protective effect)
  3. genetic factors - genes or same family, same lifestyle?
  4. smoking - nicotine is vaso-constrictor, increase blood pressure which can damage endothelium
    also increases cholesterol in blood & increase chance of thrombosis
  5. stress - increases blood pressure
  6. high fat/cholesterol diet - lipoproteins made in liver from fats, cholesterol & protein, cholesterol transported in blood to damaged areas w LDL.
    higher LDL conc. = higher CHD risk (treated w statins)
    HDL in blood absorb excess cholesterol & return it to liver where it’s removed
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10
Q

respiratory surfaces should have following properties…

A

1) Large surface area
2) Permeable
3) Thin walls / membranes
4) Moist….gases diffuse more readily in solution
5) Efficient transport system…. maintains a concentration gradient.

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11
Q

what is Ficke’s law?

A

rate of diffusion = SA x diff. in conc.
————————
diffusion distance

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12
Q

describe the structure of the lungs?

A
  1. Trachea (Wind pipe) - tube like structure that carries air from the mouth to the lungs
  2. Bronchi - trachea splits into 2 bronchi as it enters lungs, which allows air to travel to left and right lung (singular: Bronchus)
  3. Bronchioles - Bronchi divide into smaller branches called bronchioles. These supply alveoli with air.
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13
Q

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

A
  • Many alveoli/ alveoli walls folded provide a large surface area;
  • Many capillaries provide a large surface area (So) fast diffusion;
    Alveoli or capillary walls/ epithelium/ lining are thin/ one cell thick / short distance between alveoli and blood;
  • Flattened/ squamous epithelium (So) short diffusion distance/ pathway / (So) fast diffusion;
  • Ventilation / circulation; So Maintains a diffusion / concentration gradient (So) fast diffusion;
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14
Q

Describe the gross structure of human gas exchange system and how we breathe in and out

A
  • Named structures – trachea, bronchi, bronchioles, alveoli
  • Above structures named in correct order
    o OR
    o Above structures labelled in correct positions on a diagram
  • Breathing in – Diaphragm contract and external intercostal muscles contract
  • Volume increases and pressure decreases in thoracic cavity.
  • Breathing out – Diaphragm relaxes and internal intercostal muscles contract
  • Volume decrease and pressure increase in thoracic cavity
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15
Q

describe the diffusion of gases in the lungs

A

deoxygenated blood from pulmonary artery has low conc. of O2 and high CO2 conc. compared w air in alveoli
blood reach capillaries around alveoli, O2 diffuse into blood across squamous epithelial membrane and endothelial wall of capillary
CO2 move from blood in pulmonary artery (high conc.) to alveoli (low conc.)

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16
Q

Describe how the movement of the diaphragm leads to air movement into the lungs

A
  1. Diaphragm contracts and flattens.
  2. Volume of lungs increases.
  3. Pressure inside the lungs is lower than
    atmospheric pressure.
  4. Air moves into the lungs.
17
Q

Describe the pathway taken by an oxygen molecule from an alveolus to the blood

A
  1. (Across) alveolar epithelium;
  2. Endothelium of capillary;
18
Q

what is pulmonary ventilation rate?

A

tidal volume (volume of air taken in each breath at rest - dm3) x breathing rate (no. breaths taken in 1 min - min-1)

19
Q

define:
1. inspiratory/expiratory reserve
2. residual volume
3. vital capacity

A

Inspiratory/Expiratory reserve – Extra volume required for a deep breath

Residual Volume – Air that remains in lungs to prevent collapse of alveoli.

Vital capacity - is the maximum amount of air a person can expel from the lungs

20
Q

risk factors of lung disease?

A
  1. smoking
  2. air pollution
  3. infection
  4. occupation (exposure to irritants)
  5. genetic pre-disposition
21
Q

what is mass flow

A
  1. bulk movement of liquids & gases due to pressure difference
  2. closed systems (liquid in tubes) more efficient than open, easier generate & maintain pressure gradient
  3. contraction of left ventricle generates high hydrostatic pressure
  4. pressure in capillaries & veins lower so blood moves down pressure gradient through arteries, arterioles, capillaries venules & into veins
22
Q

when is a specialised transport medium (plasma) and pump needed in mass flow?

A

lower SA:V, more active organism = greater need

23
Q

why do mammals have a DOUBLE circulatory system?

A
  • blood pass twice through heart for each complete circuit of body
  • when blood pass through lungs pressure reduced
  • blood returned to heart to increase pressure before circulated to rest of body
24
Q

what is one of the functions of the liver and what are the 3 blood vessels associated w the liver?

A
  • process absorbed food molecules ( e.g. glucose & AA’s) *& adjust their conc. in blood
  1. Hepatic artery - takes blood from the aorta to the liver (provides oxygen)
  2. Hepatic vein - takes blood from the liver to the vena cava
  3. Hepatic Portal Vein - takes blood from the intestines to the liver contains absorbed food molecules)
25
Q

what is a function of the kidney and what blood vessels are associated with it ?

A

excretion of nitrogenous waste & osmoregulation (maintaining correct water potential in blood).

Renal artery and vein - take blood to & from kidney

26
Q

Arteries and arterioles take blood away from the heart. Explain how the structures of the walls of arteries and arterioles are related to their functions. (6)

A

Elastic tissue:
1 Elastic tissue stretches under pressure/when heart contracts;
2 Recoils/springs back;
3 Evens out pressure/flow;
Muscle:
4 Muscle contracts;
5 Reduces diameter of lumen/vasoconstriction/constricts vessel;
6 Changes flow/pressure;
Epithelium:
7 Epithelium smooth;
8 Reduces friction/blood clots/less resistance;

27
Q

The thickness of the aorta wall changes all the time during each cardiac cycle.
Explain why. (5)

A

The thickness of the aorta wall changes all the time during each cardiac cycle.
Explain why. (5) 1. (Aorta wall) stretches;
2. Because ventricle/heart contracts / systole / pressure increases;
3. (Aorta wall) recoils;
4. Because ventricle relaxes / heart relaxes /diastole / pressure falls;
5. Maintain smooth flow / pressure;

28
Q

Describe how tissue fluid is formed and how it is returned to the circulatory system. (6)

A

Formation
1. High blood / hydrostatic pressure / pressure filtration;
2. Forces water / fluid out;
3. Large proteins remain in capillary;

Return
4. Low water potential in capillary / blood;
5. Due to (plasma) proteins;
6. Water enters capillary / blood;
7. (By) osmosis;
8. Correct reference to lymph;

29
Q

what is the lymphatic system?

A
  • force pushing liquid out at start of capillary greater than force pulling back in at end of capillary
  • more liquid leaves capillary than re-enters
  • tissue fluid cannot stay in tissue spaces or swells (oedema)
  • tissue fluid drains into open end tubes (lymphatic vessels)
  • merge together & form network running through body
  • vessels empty back into blood stream in veins in neck region
  • skeletal muscles contractions assist in movement of lymph fluid
30
Q

Heat from respiration helps mammals to maintain a constant body temperature.
Use this information to explain the relationship between the surface area to volume ratio of mammals and the oxygen dissociation curves of their haemoglobins. (5)

A
  1. Smaller mammal has greater surface area to
    volume ratio;
  2. Smaller mammal/larger SA:Vol ratio more
    heat lost (per unit body mass);
  3. Smaller mammal/larger SA:Vol ratio has
    greater rate of respiration/metabolism;
  4. Oxygen required for respiration;
    (Haemoglobin) releases more oxygen / oxygen released more readily / haemoglobin has lower affinity;
31
Q

The thickness of the aorta wall changes all the time during each cardiac cycle.
Explain why. (5)

A

The thickness of the aorta wall changes all the time during each cardiac cycle.
Explain why. (5) 1. (Aorta wall) stretches;
2. Because ventricle/heart contracts / systole / pressure increases;
3. (Aorta wall) recoils;
4. Because ventricle relaxes / heart relaxes /diastole / pressure falls;
5. Maintain smooth flow / pressure;