topic five - transport in animals - miss whitehouse Flashcards
why are transport systems needed
in multicellular organisms?
size of organism – oxygen used up by outer
layers of cells
low SA:volume ratio – surface area is not large
enough to supply all oxygen and nutrients needed
by internal cells through simple diffusion
level of activity – more active organisms need
more oxygen for the release of energy through
respiration (higher metabolic rate), carbon
dioxide also needs to be removed at a faster
rate
name five features of a good a transport system?
a circulating fluid to carry materials around the body – blood (plasma and cells)
a muscular pump to create pressure that will push the fluid around the body – the heart – composed of cardiac muscle
vessels to convey the fluid from one region to another – arteries, capillaries, and veins
exchange surfaces – enable useful materials to enter the blood and to leave it again where they are needed
two circuits (double circulation) – one to pick up oxygen and another to deliver oxygen to the tissues
in mammals the double circulatory system has two circuits what are these called?
Pulmonary circulation: • Blood to lungs • Low pressure prevents damage to capillaries in the lungs
Systemic circulation: • Blood to body organs • High pressure – blood needs to travel a great distance
single circulatory system features?
Fish
Blood passes through the heart once per complete
circuit of the body
Blood pressure is reduced as blood passes through
capillaries in gills
Blood flow is slow to rest of body
Rate of oxygen delivery limited
double circulatory system features?
Mammals
Blood passes through the heart twice per complete
circuit of the body
Heart increases blood pressure after blood has
passed through lungs
Blood flow is fast to rest of body
Rate of oxygen delivery faster
what happens in an organisation with an open circulation?
in an organism with an open circulation, blood is not enclosed in vessels but flows freely through the
body cavity
E.g. insects and some other invertebrates
what happens in an organisation with an open circulation?
in an organism with a closed circulatory system, blood is
contained in vessels -arteries, veins and
capillaries
E.g. all vertebrates
open circulation features?
chambers pump blood forwards by peristalsis
blood re-enters heart through series of valves called ostia
larger insects have some open-ended tubes attached to direct blood flow to active parts
efficient enough for insects as they have the tracheal system to deliver oxygen to cells and to remove carbon dioxide
name the types of blood vessels and what they do?
arteries: carry blood (usually oxygenated) away from the heart. arteries have thick walls and a relatively narrow lumen
arterioles: smaller vessels which carry blood between an artery and capillaries
capillaries: the smallest type of blood vessel, with walls only a single cell thick
venules: a small vessel which carries blood between a larger vein and capillaries
veins: carry blood (usually deoxygenated) back towards the heart. Veins have thin walls and a relatively large lumen and
may contain valves
name the three types of tissues in vessels?
tunica interna/intima: an endothelium lining the inside of the vessels. This is a layer of squamous epithelium that is only one cell thick
tunica media: middle band of tissue that contains smooth muscle, collagen and elastic fibres
tunica externa: outer
layer containing collagen
and elastic fibres
what do veins contains and what do these do?
veins contain semi-lunar valves formed from their
endothelium which keep blood flowing towards the heart
what do valves help?
valves help to overcome the problem of moving blood against the force of
gravity under fairly
low pressure
how have arteries adapted to there functions?
very thick walls with smooth muscle to constrict the lumen
lots of elastic fibres in tunica media allow artery walls to
stretch as blood surges through under high pressure, then recoil
relatively narrow
lumen to maintain high pressure
collagen in walls
provides strength
to withstand high
pressure
how have veins adapted to there functions?
thin walls as high pressure is not needed
wide lumen
much thinner tunica media than the arteries, with
fewer elastic fibres and less collagen
semi-lunar valves
to prevent backflow
how have capiliaries adapted to there functions?
small diameter of 7-8μm ensures that RBC pass through in single file – better for diffusion
walls made of squamous epithelium are only one cell thick – short diffusion pathway
examples of blood compostion?
red blood cells (erythrocytes)
white blood cells (leucocytes)
platelets
plasma
dissolved carbon dioxide
dissolved oxygen
glucose
amino acids
fatty acids
mineral ions
plasma proteins
hormones
antibodies
(Heat)
what do fenestrations do?
these are tiny pores that exchange of
molecules between the blood plasma and body tissues
what’s a capillary bed?
a network of capillaries within a tissue
how is tissue fluid formed?
as blood flows through the capillaries in a capillary bed some
of the molecules are forced out of the capillary
what do tissue fluid contain?
Water
dissolved oxygen
dissolved solutes e.g.
glucose, amino acids, ions
some hormones and
proteins
very few white blood cells (some phagocytes)
no plasma proteins
what does lymph fluid contain?
less oxygen and nutrients than
tissue fluid due to use by cells
more carbon dioxide than tissue
fluid due to cell waste
more fatty material from absorption in intestines
lymphocytes produced in lymph
nodes (a type of WBC)
what does systole mean?
means contraction
what does diastole mean?
means relaxation
what is a atrial systole?
both atria contract
blood flows into the ventricles
valves in the veins close to prevent the backflow of blood
high pressure in the atria forces the atrioventricular valves to open
what is a ventricular systole?
both ventricles contract
atrioventricular valves pushed shut
semilunar valves are pushed open
blood flows into the arteries
what is a ventricular diastole?
atria and ventricles relax
semilunar valves are pushed shut
blood flows into the atria through the veins, then through the open AV valves into the ventricles