Mass transport in animals Flashcards
Definition of haemoglobin
A complex protein with a quaternary structure composed of 4 polypeptides, each containing a haem group. Has an affinity to oxygen.
Equation for Hb and what it forms
Hb + 4O2–> Oxyhaemoglobin
Percentage saturation equation
maximum saturation x100
Partial pressure definition
The proportion of oxygen in a mixture of gases or a solution
pp in lungs vs respiring tissue
lungs: High PP, more O2 loaded, higher saturation, hb has a higher affinity for o2
Respiring tissue: lower pp, more o2 unloaded, lower saturation, hb lower affinity for O2
Lower pO2 means less Hb is saturated
Loading/dissociation definition
When oxygen is taken up by Hb
Unloading definition
When O2 is released by Hb
Affinity definition
A natural attraction for O2- Hb has a high affinity to oxygen.
Partial pressure in the lungs
pp of O2 is high in the capillaries, Hb has a high affinity for O2 at a high pp. haemoglobin becmes almost fully saturated as the blood cells pass through pulmonary capillaries
pp in respiring tissues
pp is lower, Hb has a lower affinity for O2 at a lower pp and so oxyhemoglobin starts to break down and unloads oxygen. Oxygen released then available to the tissue to be used in aerobic respiration
Binding cooperativity
The first O2 molecule alters the tertiary structure of the Hb molecule. This exposes the 2nd and 3rd O2 binding site- making it easier for the O2 molecules to bind and load.
Effect of Co2
High Co2- Hb affinity for O2 is even lower. If pCO2 increases the saturation of Hb decreases, causing oxygen dissociation curve to shift to the right
effect of increasing respiration rate
tissue cells respire aerobically, quickly reducing the dissolved O2 in the surrounding of the tissue fluid. this reduces the pO2 to a lower level than normal.
Oxygenated blood arriving with fully saturated hb begins to unoad more oxygen and more oxygen will be released from the haemoglobin to the tissue cell- because the surrounding pO2 is lower andso haemoglobin will have an even lower affinity
CO2 effects
makes blood more acidic- lowers pH. This alters the tertiary structure, proteins change shape- lower affinity for O2 at high levels of CO2. The more the cells respire, the more the graph will shift to the right.
Heat from respiration helps mammals to maintain a constant body temperature
Smaller mammal has greater surface area to volume ratio
so more heat lost
so greater rate of respiration
Oxygen required for aerobic respiration- hb releases more oxygen
Adaptation to Environment
Genetic differnces between species and populations leads to differnt haemoglobin affinities. Mutations cause variation affnity
3 types of Hb
- type A adult humans and species that live on land at sea level
- type B- live in an environment where pO2 is lower. They form Hb where dissociation curve is shifted to the left. Hb has a higher affinity for O2. Becomes fully saturated at a lower pO2 and rapidly unloads. Foetus similar to thus
- type C- shift to the right, for those with a higher metabolic rate. Hb has a lower affinity for O2 so dissociates from the Hb more readily. O2 is more readily available to respiring cells.
The oxygen dissociation curve of a foetus is to the left of that for its mother. Explain why
- Higher affinity, loads more oxygen
- At low high partial pressure
- oxygen moves from mother to foetus
Lugworms and their dissociation
Hb has high affinity for oxygen which enables the lugworm to saturate haemoglobin at low pO2 as between tides the O2 concentration in the burrow will be very low.
Blood flow through the heart
Function of heart is to pump blood around the body. there is a double circulatory system. Blood passes through the heart and is pumped to the lungs, returning back to the heart (pulmonary circulation). Blood no passes through the heart a second time (re-pressurised) and pumped round the body organs before returning to the heart (systemic circulation)
Blood moves around the body due to the pressure differnce between the pressure in the heart and the blood vessels- mass flow
Heart structure- valves and movement of blood
Deoxygenated blood returns from the body in the vena and enters the right atrium
The blood then passes, via an atrio-ventricular valve into the right ventricle and out, via the semi-lunar valve and pulmonary artery.
The blood then passes through the lungs and returns to the left atrium via the pulmonary vein. The blood passes through a second atrio-ventricular valve into the left ventricle and then through the semi-lunar valve into the aorta and then to the body tissues
Role of coronary arteries
branch off from the aorta and supply the heart muscle with blood
Pressure of chambers
1.blood enters the atrium. Blood volume increases pressure in atrium, pressure in atrium greater than ventricle. atrio ventricular valves open
Atrium muscles contract, further increases pressure, remaining blood forced into ventricle from atrium
- blood enters ventricle- increases pressure in ventricle due to volume of blood. pressure in ventricle greater than atrium- atrio ventricular valve closes.
- ventricle muscles contract- further increases pressure in ventricle until greater than in aorta. semi-lunar valve opens, blood enters aorta. Blood pumped to body
- Ventricle muscles relax- pressure in ventricle is less than in aorta, semi lunar valve close. blood enters atrium, blood volume increases pressure in atrium. Back to 1
sytole and diastole
Systole- contraction of heart muscle
Diastole- heart muscle relaxed
cardiac output equation
CO= SV x HR
units- dm3min-1
Atherosclerosis
Lumen of artery is narrowed due t build up of fatty deposits and cholesterol underneath the endothelium of the artery. The deposit is antheroma.
Muscle fibres and calcium salts accumulate forming hard uneven patches of plaque.
May cause reduced blood flow to heart muscle cells- muscle cells deprived of oxygen. If blocked completely will cause heart attack
Thrombosis
Plaque may rupture and trigger blood clotting. Clocks build rapidly. Thrombus- clot can travel and cause problems elsewhere
CHD risk factors
age- gradual deposit over time
gender- men more at risk than women- due to protective oestrogen up to menopause.
Genetic- Predisposition to CHD due to genes or similar lifestyles
Smoking- nicotine is a vaso-constrictor which increases blood pressure and damage to endothelium. Increase levels of cholesterol
Stress- increased blood pressure
High lipid/cholesterol diet- The greater the conc of LDL the greater risk of CHD
rate of diffusion
Diffusion distance
lung structure
Trachea- tube like structure that carries air from mouth to the lungs
Bronchi- splits into two bronchi as it enter into the lungs
Brochioles- bronchi further splits into smaller branches which supply alveoli with air
Alveoli
Large SA- rich blood supply which circulates to maintain a large concentration gradient between gases in blood and alveoli. Gases in the alveoli air spaces are seperated by the blood by the squamous epithelium and endothelial wall of capillary. Epithelium is one cell thick so thin dd.
Breathing
Inhalation- external intercostal muscles contract, diaphragm contracts and pulls down. Thoroacic cavity volume increases, pressure in lungs lower than atmospheric pressure, air moves into lungs down a pressure gradient
Exhalation- External intercostal muscles relax, diaphragm relaxes ad moves up, volume decreases, pressure in lungs greater then atmospheric so moves out of the lungs down a pressure gradient
Purpose of ventilation
maintains a concentration gradient
Pathway of oxygen from atmopshere to blood
oxygen moves through the trachea, bronchi, bronchioles and into the alveoli- oxygen then passes by diffusion through the epithelial cell of the alveoli- through the endothelial cell of the cspillsry- combines with hb
Pulmonary ventilation
pulmonary ventilation= tidal volume x breathing rate
mass flow
bulk movement of liquids and gases due to a pressure difference.
Closed systems are more efficient than open systems as its easier to maintain a pressure gradient- contraction of left ventricle generated high hydrostatic pressure.
Vena cava
main vein returning blood to the right atrium of the heart
pulmonary artery
artery taking blood from the right ventricle to the lungs
pulmonary vein
vein returning blood from the lungs to the left atrium
aorta
main artery taking blood from the heart to the organs
hepactic artery
vein
portal vein
takes blood from aorta to liver
vein- takes blood from liver to vena cava
portal- takes blood from intestines to liver
arteries
transport of blood from heart to organ. Blood is under high pressure. the wall is very thick to withstand pressure
Structure- endothelial layer- one cell thick, reduces friction for a smooth flow.
Middle- large amount of elastic protein fibres, allows wall to stretch. recoils once blood is passed- maintains high hydrostatic pressure on the blood. Contains a smooth muscle layer- muscle constricts the vessel and reduce volume of blood passing through to increase blood pressure
outer layer-fibrous proteins that gives support and strength to wall helps to resits damage
Arteriole
smaller than arteris and connect artery to cappilaries.Smaller diameter than artery- greater friction, fall in blood pressure. Elastic layer is thinner, thicker muscle layer- can be contracted to constrict the vessel
Capillary
Wall only has endothelial layer- involved in exchange of materials between blood and tissue cells. Diameter is very small with a large number of capillaries- greater friction and a high surface area, reducing blood pressure and blood flow
veins
carry blood back to the heart from the tissues, under low pressure. Similar to artery but muscle layer is thinner, no need for vaso constriction, thin elastic layer, low pressure. Have valves to prevent backflow- only allow blood to flow in one direction
In the arteries…
flow is fast and pressure is high and fluctuating due to the contraction of the left ventricle
in the capillaries
increaded cross sectional area causes increased friction which reduces blood pressure.
Role and adaptations of capillaries
very thin walls- short diffusion distance
numerous and branched- increased surface area
narrow lumen diameter- increase SA between red blood cell and capillary wall, reduced dd
wall spaces- gaps between cells of the endothelial.
Formation and return of tissue fluid
Hydrostatic pressure of blood is greater than tissue fluid, net force pushing water out of the capillary fenestrations] ultrafiltration
wp of the blood, due to plasma proteins is lower than tissue fluid, creating a water potential gradient which allows water to return to the capillary via osmosis
as blood enters the arteriole of the capillary- blood has higher hp- creating a larger pressure pushing out than pulling in due to wp difference. Fluid leaves the capillary. exchange of gases, nutrients now occurs between tissue fluid and cells.
at the venous end of the capillary water re-enters the capillary via osmosis, excess water is removed from the tissue via lymph vessels.
Describe how tissue fluid is formed and how it is returned to the circulatory system
high hydrostatic pressure forces water out, large proteins remain in capillary, lower water potential in capillary due to plasma proteins, water enters capillary via osmosis, water removed and transported to the lymph
