Chapter 8- Transport In Animals Flashcards
What happens after atrial walls relax?
Ventricle walls contract
What happens after the sinoatrial node generates electrical signals?
Walls of atria contract
What happens after atrioventricular node receives electrical signals from SAN?
Electrical signals transmitted down septum
What happens after ventricle walls contract?
Atrioventricular valves close
What happens after ventricle walls relax?
Semilunar valves close
If there are 2 ventricular systoles after the atrial systole in one heartbeat, what would happen?
Less blood leaves heart for each ventricular systole as ventricles do not have time to fill before contracting
A fetus has a hole in the septum between the R + L atria which allows blood to flow directly from right atrium to left atrium. Why?
-lungs not functioning so blood is not oxygenated in lungs thus pulmonary circuit bypassed
After birth, fetal haemoglobin replaced with adult haemoglobin. State differences + why important?
- fetal Hb has higher affinity for oxygen
- must be able to bind to oxygen in lower partial pressure in placenta
- fetal Hb contains gamma sub units
- creates higher affinity for oxygen
Why tissue fluid does not contain erythrocytes?
Too large to pass through fenestrations between endothelium cells
Role of haemoglobin in transporting oxygen around the body?
- oxygen binds to Hb in capillary to form oxyhaemoglobin
- oxygen dissociates from Hb + released to where needed
How hydrogencarbonate ions are produced in erythrocytes?
- CO2 diffuses into erythrocytes
- CO2 reacts with water + catalysed by carbonic anhydrase enzyme
- forms carbonic acid
- carbonic acid dissociates to form hydrogencarbonate ions + hydrogen ions
High concentrations of carbon dioxide in the blood reduces the amount of oxygen transported by Hb. Name this effect + why it occurs
- Bohr effect
- reduces the affinity of Hb for oxygen
- more oxygen released to where needed
- CO2 binds to Hb forming carbaminohaemoglobin
What is meant by health?
Mental + physical well being and absence of disease
Why fetal haemoglobin curve is to the left of the adult haemoglobin curve?
- fetal Hb has higher affinity for oxygen
- this is because it must be able to bind to O2 in low partial pressure in placenta
How substances that are dissolved in blood plasma such as O2 + glucose enter the tissue fluid from capillaries?
- diffusion of substances down conc gradient
- hydrostatic pressure in capillary is higher than in tissue fluid so plaster forced out down pressure gradient
- as plasma moves out glucose + oxygen leave with it
Pressure fluctuates as blood flows along aorta. Why
- ventricular systole of left ventricle increases pressure
- ventricular diastole of left ventricle decreases pressure
Term used to describe no. Of fluctuations per minute?
Heart rate
Not heart beat
What causes decrease in pressure as blood flows from sorta to arteries + arteries to capillaries?
- blood flows into larger no. of vessels
- total cross sectional area of arteries greater than of aorta
- total cross sectional area of capillaries greater than of aorta + arteries
Why is it important that the pressure drops as blood flows from aorta to capillaries?
- capillary wall is very thin as only cell thick
- high pressure would damage capillary wall
Hydrostatic pressure in arteriole blood?
High
Hydrostatic pressure in tissue fluid?
Low
Erythrocytes present in tissue fluid + lymph?
No
Advantages of keeping blood inside vessel?
- maintain high bp
- flow can be directed
How artery can withstand pressure?
- wall made of thick layer of collagen which provides strength
- endothelium is folded
- no damage to endothelium as it stretches
How artery can maintain pressure?
- thick layers of elastic fibres to cause recoil
- smooth muscle constricts lumen
Why wall of left ventricle is thicker than wall of left atrium?
-left ventricle needs to create higher pressure as pumps blood to all parts of body and thus has more muscle to create more force
How pressure changes in the heart bring about the closure of the atrioventricular valve?
- ventricular systole
- this raises pressure higher than atrial pressure
- the pressure generated by ventricular contraction pushes valves shut
How to maintain pressure of blood vessels?
- smooth muscle
- elastic tissue
- collagen
- barrow lumen
Exchange surface in mammalian circulatory system?
Capillaries
Not alveoli as that is gas exchange system
Transport medium in circulatory system?
- blood
- plasma
How can the amount of oxygen released by dissociated from oxyhaemoglobin be increased + what is this called?
- presence of more CO2
- Bohr effect
Detail visible is use scanning electron microscope?
3D shape
Detail visible if use transmission electron microscope?
Can see surface detail
Why curve for fetal Hb is to the left of the curve for adult haemoglobin?
- fetal Hb has higher affinity for oxygen
- fetal Hb must be able to bind to oxygen in lower partial pressure in placenta
- at low partial pressure of oxygen, adult Hb will dissociate
How to draw curve for Bohr shift?
- to the right of dissociation curve of adult haemoglobin
- starts from 0%
- sigmoid shape
Benefits of Bohr shift to actively respiring tissue?
- requires more oxygen
- it produces more CO2
- so Hb involved in transport of CO2
- so less Hb available to combine with CO2 so more oxygen released
Roles of sinoatrial node + atrioventricular node in cardiac cycle?
- SAN is a pacemaker which initiates the heart beat
- sends impulse over atria walls
- AVN delays impulse
- AVN sends impulse down bundle of His along Purkyne fibres
Ways in which wall of artery is different from wall of vein?
- thicker
- no valves
- endothelium is folded
- more elastic tissue
- more collagen
How high hydrostatic pressure of blood is generated in the heart?
Ventricular systole
Why hydrostatic pressure of blood drops as blood moves away from heart?
- more vessels
- vessels have larger cross sectional area
- loss of plasma from capillaries
- reduced resistance to blood flow
What happens to blood plasma at arterial end of capillary?
- hydrostatic pressure of capillary greater than water potential
- plasma moves out of blood down pressure gradient to form tissue fluid
- proteins remain in capillary as too large to pass through capillary wall
Type of muscle found in walls of heart chambers?
Cardiac
Process that creates pressure inside heart chambers?
Systole
What happens at 4th intersection?
- pressure in ventricle is lower than pressure in atrium
- atrioventricular valve opens + blood flows into ventricle
Define single circulatory system?
-blood passes through heart once for each circulation of the body
Define closed circulatory system?
Blood is maintained inside vessels
How action of heart is initiated + coordinated?
- SAN acts as a pacemaker
- impulse spreads over atrial wall
- atrial systole
- delay at AVN
- impulse spreads down septum down bundle of His
- ventricular systole from apex
Why large multicellular organisms need transport system?
- high metabolic rate
- small SA:V ratio
- diffusion too slow to supply enough nutrients
- to prevent waste products building up
Full name given to trace showing electrical activity of heart?
Electrocardiogram
ECG
Why is there a short delay between excitation of atria + excitation of ventricles?
- to allow time for atria to contract fully
- to allow tome for ventricles to fill
- so ventricles do not contract too early
Purkyne tissue carries excitation wave down septum to apex of heart. Why to apex?
- So ventricular systole starts at apex
- to push blood upwards and so efficient emptying of ventricles
How weak and irregular heartbeat could result in fatigue?
- lower bp
- less oxygenated blood pumped to body
- less O2 for oxidative phosphorylation in aerboic respiration
- less ATP produced
Fluid found in gas exhange tubes for insects?
tracheal fluid
Why need well developed transport systems?
- high metabolic rates
- small SA:V ratio
- diffusion not sufficient to maintain steep conc gradient
How refreshing the air in air sacs helps to maintain step con gradient?
- increases conc of o2
- so conc of O2 higher than that in blood
- decreases conc of CO2
- so conc of CO2 lower than that in blood
One way steep diffusion gradient is maintained?
-o2 binds with haemoglobin to keep conc in blood low
How artery adapted to withstand pressure?
- wall is thick
- thick layer of collagen
- which provides strength
- endothelium folded
How artery adapted to maintain high hydrostatic pressure?
- elastic fibres to cause recoil
- thick layers of smooth muscle to constrict lumen
What causes fluctuation in pressure as blood flows along aorta?
- systole increases pressure
- diastole decreases pressure
Why important that pressure changes as blood flows from aorta to capillaries?
- capillary wall only 1 cell thick
- high pressure would damage the capillary wall
