animal transport Flashcards
what is a singular circulatory system?
blood passes through the heart once for each complete circuit of the body
what is a double circulatory system?
blood passes through the heart twice for each complete circuit of the body
what is a closed circulatory system?
blood enclosed in blood vessels all the time
what is an open circulatory system?
blood isn’t enclosed within vessels all the time
what is the systemic and pulmonary circuit?
systemic- circuit where blood is sent to rest of body
pulmonary- circuit where blood is sent to lungs
where do arteries carry blood to?
away from the heart
how are arteries adapted to their function?
thick, muscular walls, with elastic tissue- to stretch and recoil, to maintain high pressure
endothelium is folded- maintain high pressure
what are arterioles and how are they adapted?
arteries branch into arterioles
layer of smooth muscle allows them to expand and contract, controlling amount of blood flowing into tissue
what do capillaries do?
exchange substances between blood and body’s cells
how are capillaries adapted?
-branch to increase surface area
-thin walls (one cell thick) for short diffusion pathway
-narrow lumen to squeeze O2 molecules to release oxygen
what are venules?
connected to veins, thin with muscle cells
where do veins carry blood to?
back to heart
adaptations of veins?
wide lumen
valves to prevent backflow of blood
body muscles around vein contract to help blood flow
little elastic/ muscle tissue- low pressure
order of blood vessels at top of heart from left to right?
vena cava
pulmonary artery
aorta
pulmonary vein
what do atrioventricular valves link, and where is it located?
link atria to ventricles
located between right atrium and ventricle
what do semilunar valves link and where is it located?
link ventricles to pulmonary artery and aorta
located between left and right atrium
What is tissue fluid made from?
Substances that leave blood plasma e.g oxygen, water, nutrients
Why doesn’t tissue fluid contain RBC or plasma proteins?
They are too large to leave capillary through capillary wall
How is fluid forced out of capillary artery end?
Hydrostatic pressure inside capillary is greater than in tissue fluid
How is oncotic pressure formed?
A water leave’s capillary, water potential decreases, plasma proteins generate oncotic pressure
Why does water re enter capillary at venue end?
Water potential in capillaries is lower than in tissue fluid at venule end
Oncotic pressure greater than hydrostatic pressure at venule end
What is the lymphatic system made up of?
Extra fluid that doesn’t re enter capillary returns to blood through lymphatic system
Made of lymph vessels
How is pressure altered in atria and ventricles?
Contraction and relaxation of chambers, leading to change in volume and pressure
What happens at start of cardiac cycle?
Atria contract, increasing pressure
Blood pushes into ventricles through atrioventricular valves
What happens after blood enters ventricles?
Atria relax
Ventricles contract, increasing pressure
Pressure higher in ventricles than atria
Atrioventricular valves shut to prevent back flow
Ventricular pressure higher than arteries, semilunar valves open, blood forced into arteries
What is third step of cardiac cycle?
diastole
Ventricles and atria relax (diastole)
Semilunar valves close to prevent back flow, due to high pressure in arteries
Atria fill again, due to higher pressure in veins
Pressure in ventricles lower than atria, AV valves open, blood flows passively into ventricles
Cardiac output equation?
Cardiac output= heart rate x stroke volume
Why is the heart myogenic?
It contracts and relaxes without receiving signals from nerves
Electrical activity of heart steps?
-sino atrial node sets rhythm by sending waves of electrical activity to atrial walls
-right and left atria contract
-non conductive collagen tissue prevents electrical wave from passing to ventricles
-SAN passed electrical wave to atrioventricular node
-AVN passes electrical wave to bundle of His
-passed along purkyne fibres,
- passes electrical wave along ventricle walls, contraction from bottom up
What does ECG stand for
Electrocardiogram trace
What is the QRS complex
Contraction of ventricles
What is the P wave, at start of trace?
Atrial contraction
What is the T wave, at end of trace?
Relaxation of atria and ventricles
What is tachycardia?
When the heartbeat is too fast
What is bradycardia?
Heart beats too slowly
What is ectopic heartbeat?
An extra heartbeat that interrupts rhythm (early ventricular or atrial contraction)
What is fibrillation?
An irregular heartbeat
Haemoglobin structure?
Four polypeptide chains
Haem group on each chain, containing iron (red)
Quaternary structure
How many molecules/ atoms of oxygen can one haemoglobin molecule carry?
4 oxygen molecules
8 oxygen atoms
What is the process where oxygen is joined to/ leaves haemoglobin?
Join to- association/ loading
Leaves- dissociation/ unloading
What is affinity for oxygen?
The tendency a molecule has to bind with oxygen
What is pO2
Partial pressure of oxygen
(Measurement of oxygen concentration)
How do haemoglobin affinity for oxygen affected with pO2?
Higher pO2- higher affinity for oxygen
At what pO2 does oxyhaemoglobin unload oxygen?
At a low pO2
What is an oxygen dissociation curve?
How saturated haemoglobin is with oxygen at any given partial pressure
How is ‘s’ shape formed on dissociation curve?
When haemoglobin combined with first O2 molecule, it changes shape to make loading of next easier
As haemoglobin becomes saturated, it’s harder for oxygen molecules to join
How to adult and feral haemoglobin differ?
Feral haemoglobin has a higher affinity for oxygen
What happens at placenta?
Placenta has low pO2
Adult haemoglobin unloads oxygen
Fetal haemoglobin loads oxygen at low pO2
Where is fetal haemoglobin curve compared to adult?
To the left
What is the Bohr effect?
-As cells respire, they release CO2, raising pCO2
-Rate or oxygen unloading increases
-Dissociation curve shifts to right
-Saturation of blood with oxygen is lower at a given pO2, so more oxygen is released
How does pCO2 affect pO2?
-CO2 from respiring cells enters RBC
-CO2 reacts with water to form carbonic acid
-Catalysed by carbonic anhydrase
-10% CO2 binds to haemoglobin to be carried to lungs
-carbonic acid dissociates inro H+ and HCO3-
Equation for CO2 reaction in red blood cells?
CO2 + H2O —-> carbonic acid—> H+ + HCO3-
Catalysed by carbonic anhydrase
How is haemoglobonic acid formed?
Increase in H+ causes oxyhaemoglobin to unload oxygen, load H+ ions
Why is haemoglobonic acid formed?
To stop H+ ions increasing cells acidity
What happens to HCO3- ions formed from carbonic acid?
Diffuse out of red blood cells, transported by blood plasma
What is the chloride shift?
Cl- ions diffuse into red blood cells to compensate for loss of HCO3-
Maintains balance of charge between RBC and plasma
