3.1.2- Transport in Animals Flashcards
what are the four types of circulatory systems?+
- open
- closed
- single
- double
what type of circulatory system do insects, fish and mammals have?
- insects= open circuit
- fish= closed, single circuit
- mammals= closed, double circuit
what do all mass transport/circulatory systems have?
- fluid/medium to carry nutrients and oxygen
- tubes/vessels to carry transport medium
- pumping mechanism to create pressure to move/push fluid around the body.
what is the function of ARTERIES?
= to send blood from the heart
what is the function of VEINS
=to send blood to the heart
what is the function of CAPILLARIES?
= to exchange material with tissue.
what do arteries branch off into?
arterioles
what do veins branch off into?
venules
what are the four layers that arteries and veins contain?
- collagen fibres
- smooth muscle
- elastic fibres
- lumen endothelium
which vessel has the thickest wall?
= arteries
what does the structure of the artery include
- narrow lumen
- thick wall
- large amounts of smooth muscle and elastic fibres
what are the elastic fibres in artery walls do?
- enable the artery to withstand the force of the blood pumped out of the heart
- stretch to take larger volumes of blood
why do arteries have smooth muscle
it is smooth so that blood can easily flow over it
why do arterioles have more smooth muscle and less elastic fibres compared to arteries?
- little pulse surge
- muscles can constrict/dilateto control blood flow into organs.
what is VASCOCONSTRICTION
when the smooth muscle in the arteriole contracts, it constricts the vessel, which then prevents blood flow into the capillary bed.
what is VASODILATION?
when the smooth muscle relaxes, blood flows through the capillary bed
what are the components of veins?
- wide lumen
- thin wall
- small amount of muscle + elastic fibres
- valves
which vessel has high pressure?
artery
which vessels have low pressure?
veins + capillary.
how are capillaries structured for their role?
- large surface area for diffusion in/out of blood.
- total cross sectional area is greater than the arteriole supplying them, rate of blood flow falls
- walls are one endothelial cell thick, thin layer for diffusion.
why do veins contain valves?
to prevent the backflow of blood.
valves close when blood tries to flow backwards.
how much of a human’s blood volume is in the veins at one time?
up to 60%
when does blood move along veins?
when skeletal muscles contract.
what is the order of flow of blood?
artery–> arterioles–> capillaries–> venules–> veins
what are the four components of the blood?
- erythrocytes (red blood cells)
- platelets
- leucocytes (white blood cells)
- plasma
what does the blood plasma contain?
- glucose
- amino acids
- mineral ions
- hormones
- carbon dioxide
- oxygen
what is tissue fluid?
a liquid that contains oxygen and nutrients, supplying tissues with essential solutes in exchange for waste products.
the amount of liquid that leaks from the capillary to form tissue fluid depends on what?
- relative hydrostatic pressure
- oncotic pressure
what is hydrostatic pressure ?
the surge of blood that occurs every time the heart contracts
what is oncotic pressure?
the tendency of water to move into the blood by osmosis
how is tissue fluid formed?
when the hydrostatic pressure is higher than oncotic pressure, water is attracted in to the capillary, so fluid is squeezed out
this fluid fills the spaces between cells.
how do you work out filtration pressure?
hydrostatic pressure - oncotic pressure
how does tissue fluid become lymph?
tissue fluid drains into lymphatic vessel through the one way valves, becoming lymph.
what is lymph?
the large molecules that cannot pass through the capillary wall (and can’t become tissue fluid or drain into the blood)
what are lymph capillaries like?
- closed ends
- large pores, allowing large molecules to pass through
- separate from the circulatory system
- liquid moves along them by compression caused by body movement
where does lymph reenter the blood stream?
through veins near the heart.
what is the composition of blood?
red blood cells, white blood cells, platelets and plasma
what is the composition of tissue fluid?
O2 , CO2 , sugars, salts, amino acids, hormones, coezymes & white blood cells.
what is the composition of lymph?
carbon dioxide, proteins, glucose and white blood cells
how many chambers does the mammalian heart contain, and what are they called?
4 chambers
- right and left atrium
- right and left ventricle
what are the key features of the external structure of the heart?
- off centre in left of chest cavity
- coronary arteries lay over surface
what causes angina or heart attacks?
if the arteries on the surface of the heart, become restricted, so the heart muscle reduce delivery.
what are some details of the internal structure of the heart
- 4 chambers
- vena cava
- pulmonary vein
- aorta
- pulmonary artery
what are the names of the different valves in the heart?
- tricuspid valve + bicuspid valve
- mitral valve
- pulmonary/semi-lunar valve
- aortic valve
how do you work out heart rate of the cardiac cycle?
heart rate = 60 / cycle time(s)
how many stages of the cardiac cycle are there, and what are they called?
there are 3 stages
- atrial systole
- ventricular systole
- diastole
what is systole?
when the heart contracts
what is diastole?
when the heart relaxes
what happens during atrial systole?
-atria contracts, which forces small amounts of blood into the relaxed ventricles
what happens during ventricular systole?
- ventricular contraction
- AV valve closes
- blood is forced out of pulmonary artery and aorta.
- rise in ventricular pressure, semilunar valves open
what happens during diastole?
- ventricles relax, so pressure drops and blood flows back against cusps of sl valves, so they close
- blood flows into relaxed atria and ventricles
- as all chambers are relaxed, the ventricles fill passively.
when do the ATRIOVENTRICULAR VALVES and SEMILUNAR VALVES open?
AV= diastole SL= systole
when do the ATRIOVENTRICULAR VALVES and SEMILUNAR VALVES close?
AV= systole SL= diastole
what is the definition of the cardiac cycle?
the sequence of events that make up on single heartbeat.
what are the role of valves in the cardiac cycle?
to stop backflow of blood
what are the pressure changes during the cardiac cycle?
systole= contraction so pressure rises diastole= relaxation, so pressure decreases
how do you work out cardiac output?
cardiac output = heart rate X stroke volume
what is the functions of blood?
the transport of
- co2 and o2
- digested food from small intestines
- nitrogenous waste
- chemical messages
- platelets to damaged areas
- cells/antibodies in immune response
what part of the blood carries oxygen?
red blood cells
when does oxygen enter the body?
during respiration
how does oxygen get to the red blood cell from the plasma in the capillaries?
oxygen diffuses across the plasma membrane of the red blood cells into the cytoplasm
what does oxygen bind with in the rbc and what does this form?
oxygen bind with haemoglobin to form oxyhaemoglobin
whats the equation for the oxygen binding with haemoglobin?
Hb + 4O2 —> Hb (O2) 4
what type of protein is Hb?
= a large, globular protein, with 4 peptide chains (each with an iron-containing haem prosthetic group.
how many subunits does Hb have?
4
how many oxygens can each Hb bind to?
4
what does each subunit in Hb consists of?
a polypeptide chain and a haemoglobin (non-protein) group.
-haem group contains single iron atoms
what does the iron atom in the haem group do?
attracts and holds oxygen molecule, meaning the group has an affinity for oxygen
what does the Hb’s ability to take up + release oxygen depend on?
the amount of oxygen in the surrounding tissue
what is the partial pressure of oxygen / oxygen tension?
the pressure that oxygen contributes to a mixture of gases
if the amount of oxygen is great, what is partial pressure like?
also great
what are the axis on the oxygen dissociation graph
- percentage saturation of Hb
- partial pressure of oxygen
what is the shape of the line on this OD graph?
an S shape
what is the conformal change?
the adjustments of a proteins tertiary structure in response to external factors.
what is positive cooperativity?
the effect of the substrate being able to bind to a second subunit
what is PC seen as on the curve on the graph?
when the curve rises steeply
what does a small change in partial pressure cause, to do with oxygen?
a large change in the amount of oxygen that haemoglobin carries.
why is it difficult to achieve 100% saturation of Hb molecules?
it is difficult for the fourth oxygen molecule to diffuse in and associate, due to the other 3 oxygens.
when does Hb have increased oxygen affinity?
when more oxygen molecules bind to it.
what is foetal Hb?
a slightly different protein, with a higher affinity to oxygen.
what does a higher affinity mean?
there is higher partial pressure of oxygen to saturate 50% of Hb.
why does foetal Hb have a higher affinity?
if affinity was the same as mothers, then little/no oxygen would transfer, as they get their oxygen via the mother’s blood via the placenta.
what is the BOHR EFFECT?
the change when the partial pressure of CO2 rises, so the Hb gives up oxygen more easily.
the increase in CO2 conc causes a shift in the O2 dissociation curve
what happens to the line on the graph due to the BOHR EFFECT?
line moves up or down from orginal
why is the bohr effect IMPORTANT?
- active respiring tissue have a high PPCO2, so haemoglobin gives up O2 more easily
- in lungs, CO2 is low, so oxygen binds easily.
if the BOHR EFFECT leads to the curve being above the normal line, what does this mean?
low CO2, high ph
if the BOHR EFFECT leads to the curve being below the normal line, what does this mean?
high CO2, low ph
what are the 3 ways in which carbon dioxide is transported?
- in aqueous solution in the blood plasma.
- in combination with haemoglobin.
- in the form of hydrogen carbonate ions.
what enzyme is present within red blood cells?
carbonic anhydrase
what does the reaction of carbon dioxide and water create in the red blood cell?
CARBONIC ACID
H2CO3
what does the dissociation reaction of carbonic acid create?
hydrogen ions + hydrogencarbonate ions
H+) ( HCO3+
when the hydrogen ions form with Hb, what does this form/do?
- forms haemoglobic acid (HHb)
- this then releases the oxygen it is carrying
why does Hb act as a buffer?
- it ‘mops up’ H+
- if H+ was left in blood, then blood would become very acidic
- this means that it remains at around 7.4 pH
what does the reaction that produces hydrogen cause?
a decrease in the pH.
how much CO2 is carried in the plasma
about 5% (dissolved)
how much CO2 combines with amino groups to form carbaminohaemoglobin?
10-20%
how much CO2 converts into hydrogen carbonate ions in RBC?
75-85%
what is CHLORIDE SHIFT?
when the electrical balance of the cell is maintained due to hydrogen carbonate ions moving out of the RBC and chloride ions moving into it.
