Chapter 8- Transport in Mammals Flashcards
what does a closed circulatory system mean
Blood is pumped around the body and is always contained within a network of blood vessels
what is double circulation
This means that blood passes through the heart twice in one complete circulation
differentiate pulmonary and systematic circulation
pulmonary- blood is pumped to the heart from the right side via pulmonary artery, blood is pumped back to the heart via pulmonary vein
Systematic- blood is pumped from the left ventricle to the rest of the body via the aorta, it is then transported back to the right ventricle via vena cava
state the functions of the main blood vessels
> >
- Aorta-Carries oxygenated blood to the body
- Vena Cava- carries deoxygenated blood from the body to the heart
- Pulmonary artery- carries deoxygenated blood from the heart to the lungs
- pulmonary vein- carries oxygenated blood from lungs to the heart
describe the structure of an artery
1-Tunica external the outer layer containing elastic fibres, collagen and smooth muscles, which prevents the artery from bursting
2-Tunica media- the middle layer with elastic fibres, collagen and smooth muscles mainly consisting of elastic fibres to allow it to stretch and recoil depending on their pressure
3-Tunica intimal- made up of a layer of endothelial cells
what are the 2 types of arteries
-Elastic arteries
-Muscular arteries
describe how elastic arteries operate
-* the elasticity helps them stretch and recoil to accommodate the pressure of blood when the ventricles contract. the artery wall recoils when pressure reduces in order to increase it.*
state 3 features of arterioles
- they contain lots of smooth muscles in the middle layer
- Their **narrowness **provides resistance to blood flow
- they **regulate blood **flow from the arteries to the capillary
describe the structure of the vein
1-they have a thin tunica media meaning few elastic fibres and smooth muscles
2- they have a wide lumen
3-veins have valves called semi-lunar valves at intervals which allows one direction of blood to prevent the back flow of blood
4-blood moves at a very low pressure
describe capillaries
> >
- smaller blood vessels in the body
- their walls are made of one Layer of endothelial cells
- they Bring blood very close to body tissues to allow exchange of substances
- their walls have tiny pores allowing exchange of substances
give 3 features of venules
-are made by a union of capillaries
-collect blood from body tissue
-their walls consist of endothelium and have a thin tunica media
what is blood plasma
Is a slightly alkaline liquid consisting mainly of water and other substances dissolved in it
state 5 functions of blood plasma
1> Is a solvent (water) hence allows an easier exchange of materials
2>useful nutrients are dissolved in the plasma and can be transported
3>can transport wasteful products as well
4>can transport hormones and proteins which regulate metabolic reactions
5>its high specific heat capacity maintains a stable temperature and the plasma is able to distribute heat
what is tissue fluid
This is a fluid that surrounds cells in order to allow exchange of substances in and out of cells
Main difference between tissue fluid and blood plasma
Tissue fluid have few big proteins
how is tissue fluid formed
> It forms when plasma and other materials leaks between the cells in the walls in the capillary down a hydrostatic pressure gradient
This pressure is created from the arterial end of the capillary bed
which materials are forced out into tissue fluid
- water molecules
- dissolved minerals and salts
- small proteins(anti-bodies) and amino acids
- fatty acids
- oxygen
- white blood cells
Which materials remain in the capillary
-large proteins
-red blood cells
-platelets
How is tissue fluid reabsorbed
-This is when the water molecules are taken back to the capillary.
-This is due to the large amount of proteins decreasing the water potential in the capillaries hence forces water by osmosis into it by a smaller pressure.
What are the main functions of tissue fluid
-Allows exchanging of substance
-transports waste products such as CO2 from cells
-allows supply of glucose, water ,e.t.c
describe lymph vessels and their functions
> >
- lymph vessels like veins have valves which prevent any back flow
- they have close ends and large pores that allow large molecules which could not enter capillaries to pass through
- lymph eventually re-enters the blood through veins close to the heart
- lymph movement is caused by the contraction of muscles
- bacteria and other unwanted substances are moved from the lymph by white blood cells
Describe the unusual structure of a red blood cell
1-they have a biconcave disc shape which increases their surface area: volume ratio allowing oxygen to diffuse quickly
2-the cell is very small; allows haemoglobin to be very close to the surface
allows red blood cells to squeeze through capillaries
3- they are flexible. When passing through small capillaries, red blood cells can deform and squeeze through
4-they lack a nucleus, Mitochondria and E.R leaving space for oxygen to be carried
Neutrophils VS Monocytes
Neutrophils- classified as granulocytes and have a large lobed nucleus
Monocytes- these are the biggest phagocytes classified agranulocytes and have a large kidney shaped nucleus
describe the oxygen dissociation curve
*overall the higher the partial pressure of oxygen, the higher the percentage of haemoglobin with oxygen
*the first part of the curve requires a large amount of partial pressure of oxygen for one molecule to bind to a haem group.
*when one oxygen molecule binds, it becomes relatively easier for the other 3 oxygen molecules aka the affinity of the haem groups increases
*positive cooperativity occurs as less pressure is needed this time
*the curve reduces its steepness as the 4th haem group requires more pressure to attach to an oxygen molecule due to most oxygen binding sites already being filled.
what is the Bohr effect
-It is a shift in the oxygen dissociation curve as a result of changes in the partial pressure of carbon dioxide.
compare the Bohr effect curve to the oxygen dissociation curve
It requires a higher partial pressure of oxygen for the affinity of haemoglobin and oxygen to increase. Curve shifts to the right
What is the cardiac cycle
It is a cycle of contraction and relaxation of the atria and ventricles that keeps the blood circulating around the body
what occurs in Diastole
> >
- Both ventricle and atria relax
- semi lunar valves close due to high blood pressure from aorta and pulmonary artery
- both atria from left and right sides fill with blood. It is then transported down to the ventricles once the Atrioventricular valves open.
How is the contraction of the ventricles set
1-the depolarisation is taken to the AVN
2-the AVN then delays the transmission for the blood to empty out from the atria
3-impulse is passed to the bundle of His
4-impulse then passes to the purkyne fibres and is penetrated through the septum to pass through the entire ventricles
