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
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- 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
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- 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
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- 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
what are the 2 types of white blood cells
-Phagocytes
-Lymphocytes
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
what is the main function of lymphocytes
they secrete antibodies which invade and attach onto pathogens. they have a very large nucleus
Describe haemoglobin
-It is a globular protein
-made up of 4 polypeptide chains (4 haem groups)
-each group carries one molecule of oxygen so in total 4 oxygen molecules
Haemoglobin + Oxygen =
Oxyhemoglobin
how do the 4 haem groups attach to the oxygen
- When one oxygen molecule attaches onto one polypeptide group it causes a change on the quaternary structure making it easier for the subsequent polypeptides to join to oxygen
how is oxygen transported quickly from the alveoli
The red blood cells have a low concentration of oxygen in comparison to the alveoli hence leads to a steep diffusing gradient
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.
How is carbonic acid formed
> > When respiring cells release CO2 it gets into the blood plasma
The CO2 reacts with the water in the blood plasma and creates carbonic acid
Which enzyme can catalyse the formation of carbonic acid
- Carbonic anhydrase enzyme
what are the 3 ways that CO2 can be transported
-dissolved directly in the blood plasma
-CO2 joins with haemoglobin to form carbaminohaemoglobin
-forms hydrogen carbonate ions in the blood plasma (most efficient)
how are hydrogen carbonate and hydrogen ions formed
this is due to the breakdown of carbonic acid
how is haemoglobin acid formed
When hydrogen ions attaches to a haemoglobin
How is the Ph of the blood maintained
When hydrogen ions is formed it lowers the pH.
To reduce it from falling, haemoglobin acid is formed thus haemoglobin acts as a buffer, maintaining the pH.
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.
what is the importance of the Bohr effect
The high partial pressure of CO2 causes a decrease in the affinity of haemoglobin attaching to oxygen hence causes oxygen to be released to muscles and tissues where oxygen is needed.
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
Describe the Chloride shift
-This shift occurs when HCO3 escapes out of the red blood into the plasma while Cl enters the red blood cell in order to balance out the charges.
What does the chloride sift prevent
It prevents the red blood cell from becoming too acidic while maintaining their charges
The red blood cell exchanges HCO3 with Cl using a _________________ protein in the cell membrane
Anion exchanger
describe the 4 chambers of the heart
The two top chambers are called atria and the two bottom chambers are called ventricles
What is the role of the septum and give the two types
To prevent oxygenated and deoxygenated blood from mixing
for ATRIUM- interatrium septum
VENTRICLE- inter ventricle septum
Describe the atrioventricular valves
Tricuspid- Has 3 flaps
On the right side
-Opens when the atria contracts and closes when ventricle contracts
Bicuspid- Left side
Has 2 flaps
Opens when atria contracts and closes when ventricle contracts
what are the roles of tendons
They prevent valves from turning inside out by the pressure exerted when ventricles contract
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
Describe Systole
ATRIUM:
- Both atria contract
- AV valves open to have blood rush down to ventricles
- blood flows down to ventricles
VENTRICLES:
- Both ventricles contract
- The AV valves close due to the pressure and the semilunar valves open
- blood flows from ventricles to either aorta or pulmonary artery
what occurs in Diastole
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- 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.
what is the sinoatrial and how does it cause the atria to contract
A group of cells in the right atrium that acts as the pacemaker for the heart.
It depolarises (electrically energises) triggering a wave of electrical excitement to spread across the atria
what is the name of the fibres that the Atrio- ventricular nodes are connected to
Purkyne fibres
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
How does the ECG record the waves of excitation from the heart
-it is placed on the skin and the depolarisation of the heart causes tiny electrical changes on the skin
-it shows this through a graph of voltage against time
what is the name of the abnormal rhythm that causes a disruption
Arrythmias
What can the ECG observe
-heart diseases
-abnormal rhythms
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Which parts of the body receive the highest blood pressure
- Large arteries
- capillaries
- Large veins
- Left ventricle
