mass transport in humans Flashcards
describe the double circulatory system in mammals?
- 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.
describe the heart structure?
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
Describe how the heart muscle and the heart valves maintain a one-way flow of blood from the left atrium to the aorta.
- Atrium has higher pressure than ventricle (due to filling / contraction);
- Atrioventricular valve opens;
- Ventricle has higher pressure than atrium (due to filling / contraction);
- Atrioventricular valve closes;
- Ventricle has higher pressure than aorta;
Points 1, 3, 5, and 7 must be comparative: eg higher - Semilunar valve opens;
Marks 2, 4, 6, 8 given in the correct sequence can gain 4 marks - Higher pressure in aorta than ventricle (as heart relaxes);
- Semilunar valve closes;
- (Muscle / atrial / ventricular) contraction causes increase in pressure;
what is systole and diastole?
systole - contraction of heart muscle
diastole - heart muscle relaxed
what causes a change of pressure in the heart chambers?
changes in volumes of blood in chambers and contractions of heart muscle
Explain how an arteriole can reduce the blood flow into capillaries.
- Muscle contracts;
- Constricts/narrows arteriole/lumen;
what is cardiac output and how is it calculated?
- 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
what are the 2 most common causes of blockage to coronary arteries (heart disease) and what can be the outcome?
- 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
what are the risk factors of coronary heart disease and what can this lead to?
- age - gradual deposit over time
- gender - men more risk until women menopause (oestrogen protective effect)
- genetic factors - genes or same family, same lifestyle?
- smoking - nicotine is vaso-constrictor, increase blood pressure which can damage endothelium
also increases cholesterol in blood & increase chance of thrombosis - stress - increases blood pressure
- 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
respiratory surfaces should have following properties…
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.
what is Ficke’s law?
rate of diffusion = SA x diff. in conc.
————————
diffusion distance
describe the structure of the lungs?
- Trachea (Wind pipe) - tube like structure that carries air from the mouth to the lungs
- Bronchi - trachea splits into 2 bronchi as it enters lungs, which allows air to travel to left and right lung (singular: Bronchus)
- Bronchioles - Bronchi divide into smaller branches called bronchioles. These supply alveoli with air.
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.
- 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;
Describe the gross structure of human gas exchange system and how we breathe in and out
- 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
describe the diffusion of gases in the lungs
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.)