mass transport in humans Flashcards
heart structure
- deO2 blod enters the vena cava from body and enters the right atria
- blood passes into ventricles via atrioventricular valve and out via the semi lunar valve into the pulmonary artery
- blood passes lungs into heart via pulmonary vein
- blood passes through atrioventricular valve ito left ventricle and through semi lunar valve into aorta and body tissues
explain how an arteriole can reduce the blood flow into capillaries
- muscle contracts
- contstricts lumen
describe how the heart muscle and the heart valves maintain a one way flow of blood from the left atria to the aorta
- atria has higher pressure than the ventricle
- AV valve opens
- ventricle has higher pressure than the atria
- AV valve closes
- Ventricle has higher pressure than aorta
- semi lunar valve opens
- higher pressure in aorta than ventricle
- SL valve closes
- contraction causes increase in pressure
pressure changes valve graph
COCO
1. AV CLOSE
2, SL OPEN
3. SL CLOSE
4. AV OPEN
cardiac output equation
CO = SV x HR
SV: volume of blood expelled from LV in one cycle
HR: number of cardiac cycles per minute
units: dm3/min
risk factors for coronary heart disease
- high cholesterol diet; increases levels of LDL
- high lipid diet
- lack of exercise
- smoking
- age
- STRESS
- gender
define mass flow
bulk movement of liquids (and gases) due to a pressure difference.
- closed more efficient than open systems
role of the liver
processes absorbed food molecules (eg: glucose and amino acids)
- hepatic artery: tagkes blood from aorta to liver
- hepatic vein: blood from liver to vena cava
- hepatic portal vein: blood from intestines to liver
role of kindey
osmoregulation
exctretion of nitrgoenous waste
- renal artery and vein: blood to and from kidney
artery structure
- thick walls to withstand high pressure
- endothelial layer reduces friction
- elastic layer recoils when high BP passes, maintains hydrostatic pressure of the blood
- outer layer to give strength to the wall
capillary structure
- only endothelial layer
- small diameter, greater friction, reduces BP
veins structure
- larger luman
- lower pressure blood
- muscle layer thinner than artery no need for vasoconstriction
pressure in arteries
- flow is fast
- high pressure due to contraction of LEFT ventricle
pressure in capillaries
- increases cross sectional area causes increased friction
- lower BP
CAPILLARY adaptations
- very thin walls: increases rate of diffusion
- numerous and branched: increases SA for diffusion
- narrow lumen: ensures RBCS in contact with the wall, increase SA, reduces diffusion distance
- wall spaces/fenestrations - allow rapid formation of tissue fluid and WBCs to pass
ultrafiltration
hydrostatic pressure (HP) higher in blood than tissue fluid, so water forced out of capillary fenestrations
- crates a water potential fgradient, allows osmosis to return water
describe how tissue fluid is formed and how it is returned to the circulatory system
formation
- high hydrostatic pressure
- forces fluid out
- large proteins remain in capillary
Return
- lowers water potential in capillary
- due to the plasma proteins
- water enters capillary
- by osmosis
decribe how the movement of of the diaphragm leads to air in the lungs
diaphragm contracts and flattens
- volume of lungs increase
- pressure inside lungs lower than atmospheric pressure
- air moves into lungs
describe and explain how the lungs are adapted for rapid exchange of oxygen between air in alveoli and blood in capillaries around them
- many alveoli walls folded to provide a large SA
- many capillaries provide a large SA so fast diffusion
- alveolar walls are thin so shorter diffusion distance
- squamous epitheliun so shorter diffusion distance
- ventilation so maintains a cg
describe the pathway taken by an oxygen molecule from an alveoli to the blood
- across alveoli epithelium
- endothelium of capillary
arteries and arterioles take blood away from the heart. explain how the structures of the walls of the arteries and arterioles are related to their functions
ELASTIC TISSUE
- elastic tissue stretches when under pressure
- recoils
- evens out pressure
MUSCLE
- muscle contracts
- reduces diamter of lumen
- changes pressure
EPITHELIUM
- smooth epithelium
- reduces friction
the thickness of the aorta wall changes all the time during each cardiac cycle. explain why
- aorta wall stretches
- because ventricle contracts/systole
- aorta wall recoils
- because ventricle relaxes/diastole
- maintains smooth pressure
