Topic 3B: More Exchange Systems Flashcards
Why is digestion important
Larger biological molecules in food are too big to cross the cell membranes meaning this can’t be absorbed from the gut into the blood r
What digestive enzyme breaks down starch
Amylase
What 2 polysaccharides is starch made out of
Amylose and amylopectin
How does amylase work
By catalysis hydrolysis reactions that break the glycosidic bonds in starch to produce maltose
Where is amylase produced
Salivatory glands
What are membrane-bound disaccharides
Enzymes that are attached to the cell membrane of epithelial cells lining through ileum
Helping to break down disaccharides into monosaccharides
What are lipase enzymes
Catalyse the breakdown of lipids into monoglycerides
How do lipase enzymes work
Involves hydrolysis of ester bonds in lipids
What do bile salts do and where are they produced
Produced by liver and emulsify lipids
What do micelles do
Help products of digestion to be absorbed
How are micelles formed
Monoglycerides and fatty acids stick with the bile salts to form micelles
What does exopeptidases do
Acts to hydrolyse peptide bonds at the ends of a protein molecule
What does endopeptidases do
Acts to hydrolyse peptide bonds within a protein
What does dipeptidases do
They are exopeptidases that work specifically on dipeptides
Act to separate the amino acids that make up a dipeptide by hydrolysing the peptide bond
Where are dipeptidases found
Cell-surface membrane of epithelial cells in the small intestines
What’s the role of haemoglobin
To carry oxygen around the body
What’s the structure of haemoglobin
Large protein with a quaternary structure, made up of 4 peptide chains each chain had a haem group
It can carry 4 oxygen molecules at one time
What does a haem group do
Contains iron giving Hb its red colour
What’s the name of the structure when HB and oxygen bind?
Oxyhaemoglobin
What’s the process called when oxygen joins to Hb
Association or loading
What’s the process called when oxygen leaves oxyhaemoglobin
Disassociation or unloading
What is meant by affinity for oxygen
Tendency a molecule has to bind to with oxygen
What affects affinity
Partial pressure of oxygen
What’s partial pressure of oxygen a measure of
Oxygen concentration
When does oxygen load/unload
Loads when there’s a high pO2
Unloads when there’s a low pO2
What happens when cells respire
They use up oxygen lowering Po2
What does an oxygen dissociation curve show
How saturated the haemoglobin is with oxygen at any given pO2
What is Hb like in an organism with low oxygen environments
Hb has a higher affinity for oxygen than human Hb
As there isn’t must oxygen available
Hb has to be good at loading any available o2
What is Hb like in an organism with high activity levels
Hb has a lower affinity for oxygen than human as they need Hb to easily unload oxygen so it’s available to use
How does size affect the type of Hb
Small mammals tend to have high SA:V ratio than larger mammals
So they lose heat easily and quickly so have a high metabolic rate to help keep warm
So have a increased oxygen demand meaning they have Hb with lower affinity than humans as they need Hb to easily unload o2
What is cardiovascular disease
General term used to describe diseases associated with the heart and blood vessels
What is coronary heart disease
A type of cardiovascular disease, which occurs when coronary arteries have a lot of atheromas in them which restricts blood flow to the heart muscles
It can lead to myocardial infarction
Name 4 risk factors associated with cardiovascular disease
High blood pressure
High blood cholesterol
Poor diet
Smoking
Why do large mammals need specialised mass transport
Due to larger mammals smaller sa:v ratio they need to carry raw materials from specialized exchange organs to their body cells
What is the circulatory system made up of
Heart and blood vessels
What does the heart do
Pumps blood through blood vessels to reach different parts of the body
Name the 4 blood vessels in the circulatory system
Arteries
Arterioles
Veins
Capillaries
Where does the pulmonary artery carry blood from and to
From the heart to the lungs
Where does the pulmonary vein carry blood from and to
From lungs to the heart
Where does the aorta carry blood from and to
From the heart to the body
Where does the vena cava carry blood from and to
From the body to the heart
Where does the renal artery carry blood from and to
From the body to the kidneys
Where does the renal vein carry blood from and to
Fro kidneys to the vena cava
What does the blood transport around the body
Respiratory gases
Digestion products
Metabolic waste
Hormones
How many circuits is there in the human circulatory system
and what are they
2
One from the heart to the lungs back to the heart
Other takes the blood around the body
The heart has its own blood supply where does this come from
Coronary arteries
What do arteries do
Carry blood from the heart to the rest of the body
What’s the structure of arteries
Their walls are thick and muscular and have elastic tissue to stretch and recoil as the heart beats helping to maintain the high pressure
Inner lining (endothelium) is folded allowing the artery to stretch
All arteries carry what type of blood and what is the exception
Oxygenated
Except her pulmonary arteries which take deoxygenated blood to the lungs
What are arterioles
Arteries divide into smaller vessels called arterioles
What do arterioles do
These form networks throughout the body
Blood is directed to different areas of demand in the body by muscles inside arterioles which contract to restrict the blood flow or relax to allow full blood flow
What do veins do
Take blood back to the heart under low pressure
What features do veins have making them adapted to their job
Wider lumen than equivalent arteries with very little elastic or muscles tissue
Veins contain vaves to stop there blood flowing backwards
Blood flow through veins is helped by contraction of the body muscles surrounding them
All veins carry what type of blood and what is the exception
Deoxygenated blood
Pulmonary veins which carry oxygenated blood to heart from the lungs
What do arterioles branch into
Capillaries
What is the smallest blood vessel
Capillaries
What are capillaries adapted for
Efficient diffusion
Substances are exchanged between cells and capillaries
Where are capillaries found near
Cells in exchange tissues
What are a few features of capillaries making them adapted to their functions
One cell thick which shortens diffusion pathway along with being found near cells in exchange tissue
Large number of capillaries to increase SA for exchange
What are networks of capillaries in tissue called
Capillary beds
What is tissue fluid
Fluid that surrounds cells in tissues
What is tissue fluid made from
Molecules that leave the blood plasma (oxygen, nutrients and water)
Why does tissue fluid not contain RBC’s or big proteins?
Too large to be pushed out through capillary walls
What do cells like in from tissue fluid
Oxygen and nutrients and release metabolic waste into it
What happens in capillary bed
Substances move out of the capillaries into the tissue fluid by pressure filtration
How is tissue fluid formed
At the start of the capillary bed, nearest the arteries the hydrostatic pressure inside the cap is greater than that in the tissue fluid
The difference in hydrostatic pressure means an overall outward pressure forces fluid out of the cap into spaces around the cells forming tissue fluid
So the hydrostatic pressure is much lower at the venue end of the capillary bed
Once the tissue fluid is formed what happens
Due to fluid loss an increasing conc of plasma proteins the WP at the venule end of the cap bed is lower then the WP in the tissue fluid
Meaning some water re-enters the capillaries from the tissue fluid at the venule end by osmosis
Any excess tissue fluid is drained into the lymphatic system which transports this excess fluid from the tissues and passes it back into the circulatory system
How is the left ventricle adapted to do its job effectively
And how is it different to the first ventricle
Thicker more muscular walls than the right ventricle allowing it to contact more powerfully and limp blood all the way around the body
The right side is less muscular so it’s contractions are only powerful enough to pump blood to nearby lungs
How are ventricles adapted to do its job effectively
They have thicker walls than the atria therefore they can push blood out of the heart where as the atria just need to push blood a short distance into the ventricles
What does the atrioventricular valve do (AV)
Link the atria to the ventricles and top blood flowing back into the atria when the ventricles contact
What does the semi-lunar value do (SL)
Link the ventricles to the pulmonary artery and aorta stopping blood flowing back into the heart after the ventricles contact
In the heart what do the cords do
Attract the AV values to the ventricles to stop them being forced up into the the atria when the ventricles contract
How do heart values work
They only open one way, whether they’re open or closed depends on the relative pressure of the heart chambers
If there a higher pressure behind a valve it’s forced open but if it’s a higher pressure in front of the valve it’s forces shut
Meaning that the flow of blood is unidirectional only flowing in one direction
What is the cardiac cycle
An ongoing sequence of contraction and relaxation of gut atria and ventricles led that keeps blood continuously circulating around the body
Volume of atria and ventricles changes as they contract and relax
Pressure changes also occur, due to changes in the chamber volume
What are the 3 stages if the cardiac cycle
1) Ventricles relax and atria contract
2) Ventricles contract and atria relax
3) Ventricles relax and atria relax
What happens in step one of the cardia cycle
The ventricles are relaxed and the atria contract
Decreasing the volume of chambers and increasing pressure inside the chambers
Pushing blood into the ventricles
There’s a slight increase in ventricle pressure and chamber volume d the ventricles receive the ejected blood from contacting atria
What happens in step two of the cardia cycle
The atria relax and the ventricles led contract increasing their pressure
The pressure become higher in the ventricles than the atria which forces the AV valve shut to prevent back-flow The pressure in the ventricles is also higher than the aorta and pulmonary artery
Forcing open the SL valves and blood is forced out into into these arteries
What happens in step three of the cardia cycle
The ventricles and atria both relax
Higher pressure in the pulmonary artery and aorta closes the SL valve to prevent back-flow into the ventricles
Blood returns to the heart and the atria fill again due to the higher pressure in the vena cava and pulmonary vein
In turn this starts to increase pressure in the atria
Ventricles co tune to relax and pressure falls below pressure of the atria and AV valves open
Allowing blood to flow passively into ventricles from atria
Atria contract and the whole process begins again
How do you calculate cardia output
Strove volume x heart rate
How does a atheroma form
The wall of the artery is made up of several layers
Endothelium is usually smooth and unbroken if damage occurs if it then WBC and lipids from the blood clump together under the lining to form fatty streaks
Overtime more WBC’s lipids and connective tissue build up and harden forming fibrous plaque called atheroma
This plaque partially blocks the lumen of the artery and restrict blood flow, which causes blood pressure to increase
How does an aneurysm form
It starts with the formation of atheromas
Atheroma plaques damage and weaken arteries
They also narrow arteries increasing blood pressure
When blood travels through a weakened artery at high pressure, it may push through inner layer of the artery through the outer elastic layer to form an aneurysm
This aneurysm may burst casing a haemorrhage
What is an aneurysm
A balloon-like swelling of the artery
What is a thrombosis
Formation of a blood clot
How does a thrombosis form
Starts with the formation of atheromas
An atheroma plaque can rupture the endothelium of an artery
This damages the artery wall and leaves a rough surface
Platelets and fibrin accumulate at the site of damage and form a blood clay
This can cause a com,eye blockage of the artery or it come become dislodged and block a blood vessel elsewhere in the body
Debris from the rupture can cause another blood clot to form further down the artery
How does a myocardial infarction happen (heart attack)
The blood contain oxygen needed by heart muscle cells to carry out respiration
If a coronary artery become completely blocked an area of the heart will be completely cut off from its blood supply, receiving no oxygen
This causing a heart attack
What are the effects of a heart attack
Can cause damage and death of the heart muscle
If large areas of the heart muscles are affected complete heart failure can occur which is fatal
What are some of the symptoms of a heart attack
Chest and upper body pain
Shortness of breath
Sweating
How is high blood pressure a risk factor for cardiovascular disease
High pressure increases the risk of damage to the artery walls
Damages walls have an increased risk of atheroma formation causing further increase in blood pressure
Atheromas can also so cause blood clots to form which could block flow of blood to the heart which can lead to a heart attack
How is high blood cholesterol and poor diet a risk factor for cardiovascular disease
If it’s high then they risk is increased
This is because cholesterol is one of the main constituents of the fatty deposits ggat form atheromas
Atheromas can lead to increased blood pressure and blood clots which could cause a heart attack
A diet in high saturated fast is associated with high blood cholesterol levels
A diet high in salt also increases risk of CVD as it increases bp
How is smoking a risk factor for cardiovascular disease
Both carbon monoxide and nicotine found in cigarette smock increases risk of CVD and heart attacks
CO combines with Hb and reduced the amount of oxygen that is transported in the blood and also reduces the amount of oxygen available to tissues
If the heart muscle doesn’t receive enough oxygen it can lead to a heart attack
Smoking also decreases amount of antioxidants in the blood these help protect cells from damage meaning with less the coronary artery walls are mod likely to damage forming atheromas
How can we reduce the risk of CVD
Not smoke, eat less fatty foods
Exercise
What are some of that risk factors for CVD that cant be controlled
Genetic predisposition to coronary artery disease of having high blood pressure due to having another condition
