Module 3: Transport In Animals Flashcards
Why do multicellular organisms need a transport system
- small SA:V
- distance between environment and cells is to large
- rate of diffusion would be too slow
- higher metabolic rate
- more active
- need to be able to remove toxins
- need constant supply of
What are the features of a single circulatory system
- blood only passes through the heart once
- fish have a single circulatory system
- heart and exchange surface are next to each other
- usually for small animals
What are the features of a double circulatory system
- Blood passes through the heart twice
- two separate circuits pump blood (pulmonary cirucit and systemic circuit)
What are the benefits of a double circulatory system
- Gives blood an extra push
- so blood travels faster and o2 is delivered to tissues quicker
What are the features of an open circulatory system
and how does an insect use this system
-blood is not enclosed in vessels
- in an insect heart is segmented, when it contracts it pumps blood into the main artery
- main artery is open to body cavity
- blood flows through body cavity
- then blood returns to heart through waves
What are the features of a closed circulatory system
-blood is enclosed in vessels
examples in fish and mammals
What are the features of arteries?
- Thick muscular tissue
- elastic tissue which stretches and recoils (this helps maintain blood pressure)
- endothelium is smooth which helps blood flow easily
- endothelium is folded to allow artery to expand easily(helps maintain blood pressure)
What are the features of an arteriole
- more smooth muscle than arteries (allows arteriole to contract allowing blood to flow into capillaries)
- less elastic tissue
- involved in vasodilation
What are the features of capillaries
- one cell thick (for efficient diffusion)
- narrow lumen (to slow blood flow to allow diffusion to occur)
- highly branched
- narrow diameter
- spaces between cells for tissue fluid ???
What are the features of veins?
- have valves to prevent backflow of blood as pressure is low
- less elastic and muscle tissue
- large lumen to minimise friction
- Thin walls as pressure is low
What are the features of venules
- have very thin walls
- contain no elastic
- connect to capillaries and veins
What is tissue fluid
- Tissue fluid is fluid that surrounds cells
- contains glucose, amino acids, salts and oxygen
- supplies cells with nutrients
- takes waste away
How is tissue fluid formed?
-heart beats/ventricle contracts
Hydrostatic pressure in capillaries is higher than hydrostatic pressure in tissues
-fluid is forced out of capillaries (fenestrations)
-as fluid leaves, the capillaries oncotic pressure is generated by plasma proteins
-this means at venule end there is a low wp and high oncotic pressure
-so tissue fluid re-enters capillaries via osmosis
What do the lymph vessels do
- no all tissue fluid re-enters capilaries
- extra fluid drained through lymphatic system
- excess tissue fluid passes into lymph vessels
- valves in lymph stop it from going back
- move towards vessels in chest to return to the heart
What is the name of blood vessels that supply the heart with oxygen
Coronary arteries
How does deoxygenated blood move through the heart
- Oxygenated blood enters from inferior vena cava
- blood goes to RA which contracts
- blood goes through av valve (tricuspid valve)
- goes to RV which contracts
- blood goes through SL valves then out of pulmonary atery
How does oxygenated blood move through the heart
- Comes in from pulmonary vein
- goes to LA which contracts
- goes through AV valve (bicuspid valve)
- enters LV which contracts
- Pumps blood to SL valve
- pumps blood to aorta
What is the cardiac cycle
- ongoing sequence of contractions and relaxations of atria and ventricles
- keeps blood moving constantly
Describe what happens in the cardiac cycle
- Atrial systole (contraction)
- atria contract which decreases volume in atria
- but this increases pressure so blood is pumped into ventricles
- VP>AP
- so valves close to prevent backflow
- Atria systole
- atria relax and ventricles contract
- increases pressure and decreases volume of ventricle
- VP>AOP
- so semi lunar valves open which allows blood to go through to the aorta
Atria and ventricular systole
- AOP>VP
- So semi lunar valves close to prevent back flow
- Blood returns to heart
- atria begin to full again due to high pressure in vena cava
- ventricles relax
- AP>VP
- so av valves open which allows blood to flow into ventricles
What is the equation for cardiac output
Heart rate x stroke volume
Heart rate: number of beats per minute
Stroke volume: volume of blood pumped each heart beat (cm3)
What is an electrocardiograph
-used to check heart function
Can you draw and label a normal heartbeat?
-P wave: atrial contraction (depolarisation)
-QRS: ventricular contraction
T wave: diastole
(bigger the wave more electrical charge)
How do you calculate heart rate
60/t
you can from the same peak to the other peak so from p to p etc
What are the different kinds of heart problems
Bradycardia: heart rate is too slow (<60) due to problem with SAN
Tachycardia: heartbeat is too fast(>100)
Fibrillation: irregular heart rate atria or ventricles lose rhythm
Ecotopic heartbeat: extra heartbeat, can be caused in early contraction of ventricles or atria
What does myogenic mean
the heart controls its own contractions by initiating its own electrical impulses
How is the heartbeat controlled
- SAN (sinoatrial node)
- initiates electrical impulse and atrial systole
- natural pacemaker
- sends a wave of excitation over atrial wall which causes atrial systole
- band of collagen prevents wave being passed onto ventricles - atrioventricular node
- delays signal (allows atria to fully contract)
- pases signal to bundle of HIS - Bundle of HIS
- transmits signal from AVN to apex of heart
- makes walls of ventricle contract from bottom up - Purkinje fibres
- spreads impulses along ventricles
- stimulates ventricular systole
Describe the structure of haemoglobin
- large globular conjucated protein
- has 4 subunits (2 alpha, 2 beta)
- each subunit has 1 haem group
- so max o2 can bind
What is meant by positive cooperativity?
- shows positive cooperativity as binding of 1st o2 changes HB shape
- increases affinity for oxygen
- makes it easier for oxygen to bind
What does Po2 mean
-partial pressure of o2
What happens in respiring tissues
- low po2
- lower affinity for oxygen
- low oxygen conc
What happens to oxygen in the lungs
- oxygen loads
- high o2 conc
- high po2
- greater affinity for o2
- easier to bind to HB
What happens at very high po2
HB becomes saturated with oxygen
Explain the Bohr effect
-graph shifts to the right
- HB gives unloads oxygen more at higher PCO2
- this gives cells more o2
- when cells respire they produce co2
- increases rate of unloading o2
Compare fetal haemoglobin and adult haemoglobin
- structure is slightly different
- fetal haemoglobin has higher affinity for o2 than adult HB
- when blood reaches placenta (it has a low po2) so adult haemoglobin will unload
How can co2 be transported around the body
- through plasma
- can bind to haemoglobin
- reacts with water to form carbonic acid
(check this)
How is co2 transported in blood
- diffuses into RBC
- Co2 reacts with water to make carbonic acid ( which is catalysed by carbonic anhydrase)
- this dissociates into h+ and hco3- ions
- h+ bind onto haemoglobin (haemoglobnic acid)
- hco3- diffuses out of red blood cell
- cl- diffuses in (called chloride shift) which balances charge of plasma and blood
then hco3- +h+ -> h20+co2
co2 diffuses out of the lungs
