Mass Transport in Animals Flashcards
x through heart, type of blood through heart, gas exchange to tissue
single circulatory system
- blood passes through heart once in a cycle
- only deoxygenated blood in heart
- oxygenated blood from gas exchange surface transported directly to body tissue
x through heart, type of blood through heart, gas exchange to tissue
double circulatory system
- blood passes through heart twice in a cycle
- left side has only oxygenated blood and right side only deoxygenated blood
- oxygenated blood from ags exchange surface returns to heart before being transported to body tissues
2 types of circulation in double circulation
- pulmonary circulation
- systemic circulation
2 advantages of double circulation
- prevents too low BP
- improves efficiency of distribution of oxygen for aerobic respiration
4 chambers of the heart
- right atrium
- left atrium
- right ventricle
- left ventricle
describe the pathway blood takes from respiring tissues back to respiring tissues
- through vena cava
- ito right atrium
- into right ventricle
- through pulmonary artery
- into longs
- through pulmonary vein
- into left atrium
- into left ventricle
- through aorta
- to respiring tissues
valve b/w left atrium and left ventricle
bicuspid (mitral) atrioventricular valve
valve b/ right atrium and right ventricle
tricuspid atrioventricular valve
function of the AV valves
prevent backflow of blood from ventricles to atria
name the valves b/w the ventricles and arteries
semilunar
what prevents the AV valves inverting
chordae tendinaea
what muscle attaches tendons to the heart wall?
papillary muscles
what separates the ventricles?
interventricular septum
why does the left ventricle have a ticker wall?
to create pressure needed to pump blood around the body
cardiac output formula
stroke volume x heart rate
define cardiac output
volume of blood pumped per minute
stroke volume
volume of blood pumped by the LV per heart beat
order of valves on the cardiac cycle graph
- AV valves close
- SL valves open
- SL valves close
- AV valves open
3 phases of the cardiac cycle
atrial systole, ventricular systole, diastole
pressure gradients during atrial systole
- artery»ventricle
- atrium»ventricle
pressure gradients during ventricular systole
- ventricle»atrium
- ventricle»artery
Pressure gradients during diastole
- artery»ventricle
- antrium»ventricle
partial pressure
pressure one gas exerts within a mixture (kPa)
structure of a Hb molecule
- quaternary structure
- 4 polypeptides (2 alpha, 2 beta)
- 4 haem groups each containing an iron ion (Fe++)
function of a haem group
associates with 1 O2 molecule so it can be transported to respiring tissues from the lungs
equation for oxyhaemoglobin
Hb + 4O2 = HbO8
cooperative binding
binding of O2 to Hb causes a conformational change to Hb, making it easier for the next O2 to bind
why is the fourth binding of O2 and Hb harder?
it requires a very high pO2
why is it hard for the first O2 to bind to Hb?
the polypeptide chains of the Hb are tightly bound together
define affinity
tendency of Hb to combine/associate with O2
how is an increased rate of respiration maintained?
- increased respiration in respiring tissue
- small decrease in ppO2 in plasma
- large decrease in % saturation of Hb
- more O2 unloaded to the respiring tissue
- increased respiration rate maintained
average pO2 of a respiring tissue versus a respiring muscle tissue
- ppO2 2
- ppO2 4
why does the steepness of the curve in the middle help tissue function more efficiently?
- small change in ppO2 of blood at the respiring tissue results in a large decrease in the % saturation
- tissues receive a lot more O2 to maintain aerobic respiration
- aerobic respiration more efficient than anaerobic respiration
explain the process of oxygen loading
- in the lungs, O2 diffuses into the blood plasma
- pO2 increases
- increased affinity
- association of O2
- Hb + 4O2 = HbO8
explain the process of oxygen unloading
- at respiring tissues, O2 diffuses out bood plasma
- pO2 decreases
- affinity decreases
- dissociation of O2
- HbO8 -> Hb +4O2
Mass transport
The bulk movement of liquids or gases in one direction, usually through a system of tubes or vessels
5 types of blood vessel
- artery
- arteriole
- capillary
- venule
- vein
why are there more fluctuations in BP at the aorta?
- aorta directly linked to left ventricle whic has a higher BP
- aorta has stretch and recoil due to elastic tissue
which vessel has the lowest BP and why?
vein as furthest from last pump
how does an increase in number of blood vessels result in a decreased flow rate?
as number of vessels increases, friction increases, so BP decreases so low rate decreases
why is rate of blood flow lower at capillaries?
so exchange can occur
function of smooth muscle in arterioles?
redistribute blood through vasoconstriction and vasodilation
why do arteries have thick layer of smooth muscle and elastic fibres?
- muscle = contract maintain BP
- elastic = contract to withstand and recoil to maintain BP
why is the endothelium of blood vessels smooth?
reduce friction
why do arteries have a narrow lumen?
maintains high BP
diameter of an artery
0.1-10nm
diameter of a vein
0.1 - 10nm
function of semilunar valves in veins
prevent backflow of blood
why do veins have a narrow lumen?
reduces frictional resistance so blood flows faster
diameter of a capillary
8 micrometres
function of the basement membrane in capillaries
prevent proteins passing out the capillary
name and functon of the pores in the capillary wall?
fenestrations - allow formation of tissue fluid
how to RBCs reduce blood flow rate in capillaries?
have to pass through single file
why is the lumen of cpaillaries so narrow?
- increases total CS area
- more SA in contact with blood
- increased friction
- decreased flow rate
- increased rate exchange
how does contraction of skeletal muscle allow venous return
- skeletal muscle around vein contracts and squeezes vein
- volume in vein decreases and pressure increases
- forces valve in from of poit of contraction open and valve behind shut
- prevent backflow of blood and ensure unidirectional flow of blood back to heart
how does atrial diastole create a suction effect on blood?
pressure decreases below systemic pressure
how does inhalation create a suction effect on blood?
increase volume of horacic cavity, decreases pressure in thorax, blood flows down a pressure gradient
4 functions of blood
- transport fluid
- thermoregulation in endotherms
- immune response
- maintains pH of body fluid
ratio of cells to plasma in blood
45:55
cell contents of blood
- erythrocytes
- leukocytes
- thrombocytes
7 contents of blood plasma
- water
- proteins
- ions
- nutrients
- waste
- hormones
- gases
4 adaptations of RBCs for more efficient O2 transport and exchange
- flattened biconcave shape
- no organelles
- high concentrations of Hb
- diameter is larger than the capillary lumen
what is tissue fluid?
blood plasma without proteins or blood cells
4 steps of tissue fluid formation
- ultrifiltration of tissue fluid - blood plasma is forced out capillary at arteriole end due to high hydrostatic pressure; some osmosis due to low WP in capillary
- substances exchanged with cells
- absorption of waste products and osmosis of water due to low WP in blood and low hydrostatic pressure
- excess tissue fluid drains into lymph vessel to prevent swelling
why is the WP lower in the blood in the venule end?
most water has left capillary into tissue and proteins have remained behind as cannot pass through capillary fenestrations nad basement membrane
what 2 things ensure unidirectional flow in lymph vessel?
- blind-ended
- valves
5 steps of tissue fluid drainage in lymph
- pressure in tissue opens flaps
- tissue fluid flows into vessel
- pressure increases inside, closing flaps
- lymph flows through valves to be transported
- reenters blood at subclavian or thoracic ducts
