chapter 8- transport in animals Flashcards
what are the 5 types of blood vessels
arteries, arterioles, capillaries, venules and veins
what arteries dont carry oxygenated blood
placental and pulmonary
what is the role of elastic fibres in blood vessels
to stretch and recoil providing flexibility, made of elastin (fibrous protein)
blood vessels are not tissues
but organs
how can you tell the difference between arteries and veins on a micrograph
arteries retain their shape (remains circular) and have thick musclular wall and veins collapse a bit
what is the role of smooth muscle in blood vessels
to contract and relax to change the size of the lumen
what is the role of collagen in blood vessels
to provide structural support, maintain shape and lumen
what type of protein is collagen
fibrous
what is tissue
a group of the same cells or similar cells that provide the same function
what is the inner layer of an artiery and a vein called
endothelium of tunica intima
what is the layer called in veins and arteries where the elastic and collagenous fibres are
the connective tissue
what is the “middle layer” called in arteries and beins
tunica media
what is the outside layer called in arteries and veins
tunica adventitia/externa
what is the role of arteries
to carry blood at high pressure from the heart ventricles to the tissues of the body and the lungs
what are the 3 structures of arteries that are special
narrow lumen (relative to the wall thickness)
a thick wall containing an outer layer of collagen
an inner layer of muscle and elastic fibres
what is the function of a narrow lumen in arteries
to maintain a high blood pressure (80-120mmHG)
what is the function of a thick wall containing an outer layer of collagen in arteries
to prevent the artery from rupturing under the high pressure
what is the function of an inner layer of muscles and elastic fibres in arteries
to maintain pulse flow and controlling the diameter of the lumen, muscle also offers support to withstand pressure but not s much as collagen, the elastic fibres recoil to smooth out the pulse
explain how muscle fibres in arteries contorl the flow of blood
they help to form a rigid arterial wall that is capable of withstanding a high blood pressure without rupturing , can also contract to narrow the lumen which increases the pressure between pumps and helps to maintain bp throughout the cardiac cycle
what are pulses
when blood is expelled from the heart upon ventricular systole it flows through the arteries in repeated surges called pulses at a high pressure
what is the difference in the size of the lumens in arteries and veinss
arteries have a narrow lumen relative to the arterial wall and veins have a large lumen relative to the venular wall
why is the pressure in capillaries low
high pressure is dissipated by extensive branching of vessels and narrowing of the lumen
what are the 3 features of capillaries
vary narrow diameter
thin walls only 1 cell thick
walls are leaky (gaps in the endothelium)
what is the function of a very narrow diameter in capillaries
reduces blood flow (erythrocytes 7.5-8micrometres so they go single file) to allow time and sa for exchange between blood and surrounding cells to take place more efficiently.
what is the function of thin walls in capillaries
the ensure max rate of transfer between blood and surrounding tissue fluid (SDP) they do not need to withstand high pressure
what is the function of leaky walls in capillaries
to allow plasma and dissolved substances to leave the blood, high permeability
what are the walls of capillaries composed of
endothelium only (1 cell thick)
capillaries are surrounded by
interstitial fluid or tissue fluid
what is the flow of blood like in capillaries
very slow for maximal material change
what is the pressure like in capillaries
very low
what are the differences in pressure at different points in the capillary
the arterial end is the highest (+10), the mid capillary is 0 and the venous end is -7
what happens at the arterial end of the capillary
fluid exits as capillary hydrostatic fluid is greater than the blood osmotic pressure
what is hydrostatic pressure
pressure due to a fluid
what happens at the mid capillary
no net fluid movement as capillary hydrostatic pressure is equal to blood osmotic pressure
what happens at the venous end of the capillary
fluid re-enters the capillary as capillary hydrostatic pressure is less than the blood osmotic pressure
what is in the fluid that exits the capillary
oxygen and nutrients needed for respiration
what is in the fluid that re-enters the capillary
at body tissues- carbon dioxide and urea (waste produced by cells)
what are the types of capillaries
continuous
fenestrated
sinusoid (although not said sinisoid capillary)
fenestrated capillaries contain what
pores
some capillaries are sinusoid what does this mean
that they have open spaces between cells and be permeable to large molecules and cells
where are continuous capillaries
in the brain
explain the proportions of tissue and muscle in the aorta
mostly elastic fibres
then collagen
a bit of smooth muscle
collagen for support from high bp and elastin to smooth pulse which is high because it is close to the heart
what are the proportions of tissue and muscle in a regular artery
lots of elastic fibres and smooth muscle and then a small amount of collagen (least for all arteries)
explain what the proportions of tissue and muscle are in an arteriole
mostly smooth muscle for constriction to control flow, then smaller but equal amounts of elastic fibres and collagen because the pressure is lower and so the pulse surge is less and so the collagen is less.
what is the purpose of continuous capillaries
the are continuous with endothelial cells held together by tight junctions to limit the permeability of large molecules forming the blood-brain barrier (in the cns)
what are the 3 things to remember about vein structure
very wide lumen (relative to wall thickness)
a thin wall containing lots of collagen but not lots of elastic fibres and smooth muscle
valves
what are the function of valves in veins q
to prevent backflow which is possible with the low pressure and to maintain unidirectional flow back to the heart, it also prevents pooling at the extremities.
what is the function of a very wide lumen in veins
to maximise blood flow for more effective return
what is the function of a thin wall in veins
because the bp is very low in veins (5-10 mmHG)
which veins carry oxygenated blood
pulmonary and umbilical vein
is there a pulse in veins
no as it is lost in capillaries
as veins decrease in size what happens to the levels of…
as veins decrease in size the elastin and smooth muscle decreases
in venules there are no
elastic fibres and smooth muscle
in a large vein what is there most of
collagen and smooth muscle with some but not loads of elastic fibres
several ….. will spilt from one…..
venules
vein
low bp is veins can make it difficult for what
for the blood to move against the downward force of gravity
how can the flow of blood in veins be impacted by muscles
skeletal muscle groups facilitate venous blood flow via periodic contractions, when they contract they squeeze the vein and cause the blood to flow
what else can cause the blood in veins to flow (not valves or muscles)
arteries, which usually run parallel to veins, can cause a similar effect to skeletal muscle, by causing a rhythmic aterial bulge created by a pulse
what is a superficial vein
one that is close to the skins surface and can sometimes be seen the naked eye
what%
what supplies the cardiac muscle with oxygenated blood
coronary arteries
cardiac muscle does not get….
fatigued, does not need to rest
how many pumps does the heart consist of
2
what prevents the blood from the 2 sides of the heart from mixing
septum
the heart is surrounded by
inelastic pericardial membranes which help prevent the heart from over distending with the blood
roles of the pericardium
creates a closed chamber with sub atmospheric pressure that aids atrial filling and prevents it from over distending .
sheilds the heart by reducing external friction by lubricating it
acts as a barrier against infection
what are the 2 atrioventricular valves and why are they called that
tricuspid (right AV valve)
bicuspid (left AV valve)
they separate the atria from the ventricles
what are the 2 semilunar valves
pulmonary valve
aortic valve
they are in arteries
new things to remember about the heart structure
aortic arch
carotid arteries
descending aorta
left and right PA
septum
tendinous cords/tendon
pericardium
blood with a lower concentration of co2 has….. (sat)
a higher percentage saturation of haemoglobin with oxygen
at lower co2 concentrations, oxygen associated…… and dissociates…..
associated more readily and dissociates less readily
at higher carbon dioxide concentration oxygen associates and dissociates…
dissociated more readily
and associates less readily
why is the left side of the heart thicker than the right
left requires more force to pump the blood to the extrememties at high pressure and needs to overcome the resistance of the aorta and arterial systems of the whole body. the right side has to only pump blood to the lungs which is closer and only has to overcome the resistance of the pulmonary system
cardiac muscle cells have more what, and how is this useful
mitochondria, there is an increased reliance on and more aerobic respiration taking place so more is needed as it is beating all the time so there is more mitochondria than in skeletal muscle cells
cardiac muscle cells are….. (structure)
bracnches for faster signal propagation and contraction in three dimensions and are connected by gap junctions (so they are not fused together) at intercalated discs
what is the word for a cell that has one nucleus give an example for this topic
uninucleate
cardiac muscle (myocardium)
distending means to
swell/increase in size/any other value
cardiac muscle has a longer period of
period of contraction and refraction which is needed to maintain a viable heart beat
the heart tissue does not become
fatigued allowing for continuous life long contraction
Name the molecule formed when hydrogen ions react with haemoglobin.
haemoglobinic acid
what ph does thrombin requrie to function
ph8
what is thrombin and what does it do
it is an enzyme which plays an important role in clot formation in the blood
explain how h+ ions reacting with hb help thrombin to function
the reaction causes the free h+ ions to be removed increasing blood ph
blood ph can be decreases y
what causes blood ph to drop
too many free h+ ions in the blood
when the carbon dioxide concentration in the blood decreases the oxyhaemoglobin dissociation curve shifts to the
left
When the concentration of carbon dioxide in the blood decreases, the oxyhaemoglobin dissociation curve shifts to the left. This means that…
oxygen associates more readily (hb has a higher affinity for o2) and dissociates less readily
when does the oxyhaemoglobin curve shift to the right
when the conc of co2 in the blood increases
increasing the concentration of co2 in the blood does what to hbs affinity for o2
it decreases haemoglobins affinity for oxygen
Decreasing the concentration of H+ ions in the blood does what to Hbs affinity for oxyegn
increases haemoglobin’s affinity for oxygen.
Decreasing the acidity of the blood does what to Hbs affinity for oxyegn
increases haemoglobin’s affinity for oxygen.
The release of lactic acid by anaerobically respiring cells does what to Hbs affinity for oxygen
decreases haemoglobin’s affinity for oxygen.
Rapid exhalation does what to Hbs affinity for oxygen
increases haemoglobin’s affinity for oxygen.
chloride shift
When the blood reaches the lung tissue where there is a relatively low concentration of carbon dioxide, carbonic anhydrase catalyses the reverse reaction, breaking down carbonic acid into carbon dioxide and water. Hydrogen carbonate ions diffuse back into the erythrocytes and react with hydrogen ions to form more carbonic acid. When this is broken down by carbonic anhydrase it releases free carbon dioxide, which diffuses out of the blood into the lungs. Chloride ions diffuse out of the red blood cells back into the plasma down an electrochemical gradient.
how is foetal haemoglobin different to adult haemoglobin
It has a higher affinity for oxygen than adult haemoglobin
By the time the baby is
6 months old, most of its foetal haemoglobin has been replaced with adult haemoglobin. Suggest why this is advantageous for the baby.
The baby can supply more oxygen to its tissues, which are more active than the foetus’ tissues.
