Transport in Animals Flashcards
(24 cards)
why do multicellular organisms require transport systems
large size so high metabolic rates
high demand for oxygen
what is the difference between an open and closed circulatory system
open-blood can diffuse out of vessels
closed-blood confined to vessels
what is the difference between a single and double circulatory system
single-blood passes through pump once per circuit
double-blood passes through heart twice per circuit
relate the structure of arteries to their function
thick muscular walls to withstand the high pressures
elastic tissue allows recoil
narrow lumen to maintain pressure
relate the structure of veins to their function
thin walls due to lower pressures
require valves to prevent backflow
less muscular and elastic tissue as do not have to control blood flow
relate the structure of capillaries to their function
walls only one cell thick-short diffusion distance
very narrow so can permeate tissues
numerous and highly branched providing large surface area
relate the structure of arterioles and venules to their function
branch off arteries and veins to feed blood into capillaries
smaller so that changes in pressure are more gradual
what is tissue fluid
a watery substance containing glucose, amino acids, oxygen and other nutrients
supplies these to cells and removes waste products
how is tissue fluid formed
as blood is pumped through increasingly small vessels, hydrostatic pressure is greater than oncotic pressure so fluid moves out capillaries
exchanges substances with cells
how does tissue fluid differ from blood and lymph
tissue fluid formed from blood but does not contain RBC or platelets
after tissue fluid has bathed cells it becomes lymph-so has less oxygen and more waste products
describe what happens what happens during cardiac diastole
heart is relaxed
blood enters atria increasing pressure and pushing open atrioventricular valves
allows blood to flow into ventricles
pressure in heart is lower than in arteries so semilunar valves remain closed
describe what happens during atrial systole
atria contract pushing any remaining blood into ventricles
describe what happens during ventricular systole
ventricles contract
pressure increases closing atrioventricular valves to prevent backflow
opens semilunar valves
blood flows into arteries
how do you calculate cardiac output
heart rate x stroke volume
what does myogenic mean
hearts contraction initiated from within the muscle
explain how the heart contracts
SAN initiates and spreads impulse across atria so they contract
AVN receives, delays and conveys the impulse down the bundle of His
impulse travels into Purkinje fibres which branch across ventricles-contract from bottom up
what is an electrocardiogram
a graph showing amount of electrical activity in the heart
describe the types of abnormal activity seen on ECG
Tachycardia -fast heartbeat (over 100)
bradycardia- slow heartbeat (under 60)
fibrillation- irregular, fast heartrate
ectopic-early or extra heart beats
describe the role of haemoglobin
present in red blood cells
oxygen molecules bind to haem groups and carried around in the blood
how does partial pressure of oxygen affect oxygen-haemoglobin binding
as partial pressure of oxygen increases, the affinity of haemoglobin for oxygen increases
oxygen binds tightly to haemoglobin
when partial pressure is low oxygen is released from haemoglobin
describe the bohr affect
as partial pressure of carbon dioxide increases, the conditions become acidic causing haemoglobin to change shape
affinity of haemoglobin for oxygen decreases so oxygen is released
explain the role of carbonic anhydrase in Bohr effect
carbonic anhydrase present in red blood cells
converts co2 into carbonic acid which dissociates to produce H+ ions
combine with haemoglobin to form haemoglobinic acid
encourages oxygen to dissociate from haemoglobin
describe the chloride shift
intake of chloride ions across a red blood cell membrane
Repolarises the cell after bicarbonate ions have moved out
how does foetal haemoglobin differ from adult haemoglobin
partial pressure of oxygen is low by the time it reaches the foetus
foetal haemoglobin has higher affinity for oxygen
allows both oxygen needs to be met
