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
what is a AV valves?
after contraction, the
ventricles relax and recoil
to their original shape
this decreases pressure
in the ventricles below the
pressure in the atria
the AV valves open and
blood flows into the
ventricles
during contraction of the
ventricles, pressure
increases above the
pressure in the atria
AV valves snap closed to
prevent backflow
what happens to the semi-lunar valves during ventricle contraction?
they open as the pressure in the ventricles becomes greater than the pressure in the arteries
when the ventricles relax and recoil, the pressure
inside the ventricles falls to below the arterial pressure
this pushes the SL valves closed, as blood starting to
push backwards collects in the “pockets” of the valves
what happens in the cardiac cycle?
cardiac cycle repeats itself about 70 times each minute when the heart is at rest
when the atria contract during the phase called atrial
systole, the remaining blood in them is pushed past the
atrioventricular valves into the chambers called ventricles
contraction of these chambers forces open the semi lunar valves and pushes blood into the pulmonary
artery
then goes to the lungs, and the aorta, which supplies blood to the rest of the body
what’s lub in reference to sound of the heart?
louder
AV valves snap shut
what’s dub in reference to sound of the heart?
quieter
SL valves close
pockets fill up slowly
what does myogenic mean?
means it can initiate its own contraction - it does not require stimulation from the
nervous system like most muscles do
what are ECGs?
an ECG detects the electrical activity of the heart using sensors attached to the skin
they can be used to diagnose heart conditions
what are the different parts of the trace?
P – excitation of the atria
leading to atrial systole
QRS – excitation of the
ventricles leading to
ventricular systole
T – the start of diastole
name some conditions that are shown on an ECG trace?
Myocardial infarction –
heart attack
Atrial fibrillation – atria
contract more frequently
than the ventricles
Arrhythmia – irregular
heartbeat with lack of
coordination
Enlarged heart
what is a bradycardia mean?
heartback is too slow
what is a tachycardia mean?
heartback is too fast
what is a ectopic heartbeat?
heartbeats that are earlier than expected
how is oxygen carried and what does this form?
oxygen is carried in erythrocytes (RBC) by the
globular protein haemoglobin
this forms oxyhaemoglobin
in a reversible reaction
each subunit is associated with a prosthetic haem group, what does this contain?
containing an Fe2+ ion that has an affinity (attraction) for oxygen
how many oxygen molecules can haemoglobin carry?
four oxygen molecules
what is dissociation of oxyhaemoglobin?
happens in respiring
tissues and involves the release of oxygen from haemoglobin
what two properties to be effective, what are these?
readily associate with oxygen at a gas exchange surface
readily dissociate from oxygen at respiring tissues
what does a dissociation curve show?
shows the proportion of haemoglobin that is saturated with oxygen at different oxygen concentrations
what happens at a low oxygen tension?
haemoglobin doesn’t readily take up oxygen molecules
this is because the haem groups are in the centre of the haemoglobin molecule and the four subunits are closely united, making it difficult for the first oxygen molecule to reach the haem group and bind
what happens at an increased oxygen tension?
diffusion gradient becomes steeper
haemoglobin undergoes a conformational change – the
molecule changes shape slightly, allowing oxygen
molecules to associate with the remaining three haem
groups more easily
what happens at a very high oxygen tension?
the slope of the line levels off
this is because once three oxygen molecules have
become associated with haem groups, it is difficult for
the fourth molecule to diffuse in and bind
what must a foetus be able to do?
must be able to load oxygen from its mother’s
blood
how does respiration do to the foetus?
due to the respiration occurring in the foetus’
cells, the partial pressure (concentration) of oxygen
is lower in the foetus’ blood than in the mother’s blood
why does not much oxygen diffuse across the foetus?
because of the relatively small concentration difference
what happens in order to maximise the amount of oxygen a foetus receives?
it has a different respiratory pigment - foetal haemoglobin.
this has a higher affinity for oxygen than adult
haemoglobin at any partial pressure of oxygen, so the
foetus can always obtain oxygen from the mother’s
haemoglobin
what is myoglobin?
Myoglobin is a respiratory pigment found in muscles. It is used to store oxygen (rather to transport it)
what does myoglobin provide?
it provides a back-up supply
of oxygen for times where
muscles are using oxygen for respiration at a faster rate than it can be supplied by the blood
what are the effects of carbon monoxide ?
If carbon monoxide is breathed in it binds irreversibly with
haemoglobin to form carboxyhaemoglobin.
This means that the haemoglobin cannot load and carry oxygen
what are three forms that carbon dioxide is carried in?
5% is dissolved directly in plasma
10% is combined with amino groups in
polypeptides of haemoglobin molecule to form
carbaminohaemoglobin
85% is carried as hydrogen carbonate ions
(HCO3-) which move from erythrocytes into the
plasma
formation of hydrogen carbonate ions?
CO2 diffuses into RBCs and reacts with water (catalysed
by carbonic anhydrase). This forms carbonic acid (H2CO3)
2. Carbonic acid dissociates to form H+ ions and hydrogen
carbonate ions (HCO3-)
3. H+
ions bind to haemoglobin (haemoglobinic acid). This
means oxygen has to dissociate. It is “pushed out” due to
distortion of the molecule, which decreases affinity. This
is known as the Bohr effect. Haemoglobin is acting as a
buffer to maintain a constant blood pH
4. HCO3
-
ions diffuse out of RBCs, making them less negative.
They are carried in the plasma
5. Chloride shift: Chloride ions then diffuse into RBCs from
plasma to replace lost HCO3
-
ions and maintain the charge
label a heart?
OLC
where does an aorta come from and what does it supply?
the aorta comes up out of the heart and arches round
- the main (widest) branch runs straight down the
centre of the body parallel to the spine, and branches
off in the abdomen to supply the digestive organs,
kidneys, reproductive organs and legs
where do your carotid arteries run from?
your carotid arteries run up
the neck to the brain
where does a subclavian artery supply blood to?
the subclavian arteries supply blood to the head, neck, shoulders and arms
where does a coronary artery supply blood to?
the coronary arteries supply blood to the heart muscle
function of pulmonary vein?
the pulmonary vein brings blood in from the lungs to the left side of the heart
function of aorta?
the aorta takes blood away from the left side of the heart to the body organs
function of vena cava?
the vena cava brings blood in from the body organs to the right side
of the heart
function of pulmonary artery?
the pulmonary artery takes blood away from the right side of the heart to the lungs
what happens after contraction to the atrioventricular valves?
the ventricles relax and recoil to their original shape
this decreases pressure in
the ventricles below the
pressure in the atria
the AV valves open and
blood flows into the
ventricles
during contraction of the
ventricles, pressure
increases above the
pressure in the atria
AV valves snap closed to
prevent backflow into the
atria
what happens if there is a blockage of coronary arteries?
a blockage of these arteries leads to myocardial infarction (heart attack) because the heart muscle is deprived of oxygen and so dies
