Module 3: Exchange And Transport 3 Flashcards
What pressure does blood move from/to
Blood moves from high to low pressure
When do valves open??
When pressure above is higher than the pressure below
What initiates atrial contraction??
Sinoatrial node
What initiates ventricular contraction
Atrioventricular node
Perkeine fibres
What is double circulation
Where blood flows through the heart twice for each complete circulation of the body
Advantage of double circulation
Metabolites can reach tissues faster which speeds up metabolic processes
How is the action of the heart initiated and coordinated (5)
Sino atrial node depolarises
Wave of depolarisation spreads across the atrial muscle cells
Triggers the contraction of the atria
Depolarisation passes to the atria ventricular node to the bundle of His
The purkyne cells in the bundle of His conduct the electrical signal to cells at the base of the ventricle
Enables ventricle cells to contract simultaneously
Allows atria to contract first followed by the ventricles
Heart then repolarises and both the atria and ventricle relax
Single circulatory system
Blood flows through he heart once during each circulation of the body
Closed circulatory system
Blood enclosed in blood vessel
No direct contact with body cell
What is the likely effect on the circulatory system of a baby born with a hole in the wall between the left and right chambers of the heart
Oxygenated and deoxygenated blood will mix
Will be inefficient blood flow
Heart will pump faster
Likely effect on the circulatory system of valves not working properly
No mechanism of preventing backflow of blood
Blood not pumped at high enough pressure to reach all parts of body
Poor circulation
What type of circulatory system do insects have??
Open circulatory system
What is the circulatory system responsible for in insects?
Movement of nutrients, salts, hormones and metabolic wastes
Why does the circulatory system in insects not carry oxygen or co2
No oxygen carrying pigment present
How does blood aid thermoregulation in insects?
Helps to cool the body by conducting excess heat away from active flight muscles
Can warm the body by collecting and circulating heat absorbed while basking in the sun
What is a dorsel vessel??
Major structural component of an insects circulatory system
Tube runs longitudinally through the thorax and abdomen, along the inside of the dorsal body wall
How is the dorsel vessel divided??
Divided segmentally into chambers
Chambers separated by valves
Ensures one way flow of hemolymph
What are pulsatile organs??
Muscular pumps which act in conjunction with certain body movements to force hemolymph out into the extremities
Characteristics of the insect hemolymph
90% plasma
Watery fluid
Contains relatively high concentrations of amino acids, proteins, sugars and inorganic ions
Closed or open??
Blood flows at high pressure
Hence it is faster and more efficient system of circulation
Closed
Closed or open??
This system is present in arthropods and molluscs
Open
Closed or open??
The body tissues are in direct contact with blood
Open
Closed or open??
The body tissues are not in direct contact with the blood
Closed
Closed or open??
Suitable for animals with fast metabolism
Closed
Closed or open??
This system is present in annelids, Echinoderms and vertebrates
Closed
Closed or open??
The flow of blood is not regulated through tissues and organs
Open
Closed or open??
The flow of blood can be regulated by valves
Closed
Closed or open??
In this system, blood is pumped by the heart through large vessels into body cavities called sinuses
Open
Closed or open??
In this system, blood is pumped by the heart through a closed network of vessels
Closed
Closed or open??
Requires less energy for distributing blood
Open
Closed or open??
Blood flows at low pressure
Hence it is slower and a less efficient system of circulation
Open
Left atrium
Oxygenated blood from the lungs enters here via the pulmonary vein
Left ventricle
Blood passes into this chamber before being pumped out through the aorta
Blood is under high pressure so the wall is thick and muscular
Rich atrium
Deoxygenated blood in the vena cava passes into this chamber under low pressure
Right ventricle
Blood passes into this chamber before being pumped out into the pulmonary artery going to the lungs
Atrio ventricular valve
This thin bit of tissue prevents blood flowing backwards when blood underneath it exerts a high pressure causing it to stay shut
Semi lunar valve
Thin bit of tissue prevents blood flowing backwards into ventricles when they relax in the cardiac cycle
Septum
Separates the 2 sides of the heart
Tendinous chord
These insert into the ventricle wall are very tough and prevent what they are attached to from turning inside out
Cardiac muscle
Cells will contain numerous mitochondria and myoglobin
Cells arranged in long columns to form a fibre
Coronary artery
1st branch of the aorta
Provides oxygenated blood to the cardiac muscle
Pulmonary circulation
Circuit carrying blood to and from the lungs
Systematic circulation
Circuit of blood carrying blood around the body to the tissues
Why don’t mammals have a single circulatory system
Lower blood pressure, lower heart rate, metabolites reach tissues slower, slows down metabolic processes in comparison to a double circularity system
Insufficient to meet the demands of larger organisms
How is the heart’s rhythmic beat maintained??
Certain cells of cardiac muscle are self excitable
Rhythmic contraction of the heart occurs in a coordinated manner and is not dependent on the nervous system
Rhythmic action is generated within the cardiac muscle
Cardiac muscle
Specialised because cardiac cells are connected by intercalated discs
Transmit the force of contraction and allows rapid spread of depolarisation from one cell to another
Muscle cells operate as one unit
Depolarisation
When muscle fibres are excited by the electrical activity, it is depolarised
Depolarisation starts at the atrium, spreads all over the heart and ends at the apex of the heart
What is myocardium made up of?
Cardiac muscle fibres
Repolarisation
After complete depolarisation the heart muscle will be relaxed for a while
This is known as repolarisation
What process is depolarisation and repolarisation known as??
A continuous process
What is the function of the sinoatrial node??
Maintaining the heart’s pumping rhythm by setting the rate at which all cardiac muscle cells contract
Where is the sinoatrial node located??
Located in the wall of the right atrium near where the superior vena cava enters the heart
What does the sinoatrial node generate??
Generates electrical impulses
What impact do the sinoatrial nodes have on the walls of the atria??
Spread rapidly through the walls of the atria causing them to contract in unison
Where is the atrioventricular node found??
Found in the wall between the right atrium and right ventricle
What is the function of the atrioventricular node??
Delays the impulse for 0.1 seconds
Allows the atria to contract and empty BEFORE the ventricles contract
How long does the atrioventricular node delay the impulse for??
0.1 seconds
Is the pressure of blood high or low as it enters the capillary from the artery??
High
Why is the pressure of the blood higher as it enters the capillary from the artery??
Because it is closer to the heart
How is fluid from the plasma squeezed out of the capillary??
Through fenestrations between cells of the capillary wall
Towards the end of the capillary is blood pressure lower or higher
Lower
Why is blood pressure lower as it reaches the end of the capillary
Because it is further from the heart
Why does fluid move from the tissue fluid to the capillary??
Because there is a higher concentration of solutes in the blood/plasma due to presence of plasma proteins
Fluid as a result moves due to osmosis
What is an impulse detected by in an ECG??
Electrodes
What is the hearts electrical activity (voltage) measured by??
Measured using an oscilloscope and forms an electrocardiogram
What is the systole
Contraction of the heart, especially the ventricles, during which blood is forced into the aorta and pulmonary artery
What is a diastole
The phase of the cardiac cycle in which the heart relaxes between contractions
What is an ectopic heartbeat??
Small changes in a heartbeat which can lead to an extra beat or skipped heartbeat
Is an ectopic heartbeat dangerous??
No
What are the two most common ectopic heartbeats??
PVC - premature ventricular contractions
PAC - premature atrial contractions
What does point p represent on an ECG
Excitation in the atria
What do points QRS represent on an ECG
Excitation in the ventricle
What does point T represent on an ECG
Repolarisation
Definition of a heartbeat
One complete sequence of contraction and relaxation
3 features of blood vessels
Inner endothelium (tunica intima)
Middle layer (tunica media)
Outer layer (tunica externa)
What is the Inner endothelium made up of??
Made up of a single layer of flat cells
Why is the inner endothelium smooth??
To eliminate friction
What does the middle layer of a blood vessel contain??
Smooth muscle and elastic fibres
What does the outer layer of a blood vessel contain??
Elastic fibres and collagen
What do elastic fibres allow the artery to do??
Allows vessels to stretch with the force of blood then return to original shape
Due to recoil of fibres
How does collagen aid the arteries??
Provides tough outer layer
Helps withstand pressure
Maintains shape and volume of the vessel
What is the role of arterioles??
Link the arteries and capillaries
What are capillaries??
Microscopic blood vessels
What are capillaries made of??
Thin layer of cells
What is the benefit of capillaries being formed of a single layer of endothelial cells??
They have a short diffusion distance
How do capillaries create a large surface area??
They are numerous and highly branched
What is the diameter of the lumen of a capillary
7.5 um
What is the purpose of fenestrations??
Allow components of the blood to escape
How much blood do veins contain??
Up to 60%
Why is blood pressure low in veins??
Because the cross sectional area of the capillaries is greater than that of the arteries supplying them so pressure is lost
What is the purpose of valves in veins
Prevent the backflow of blood
What size is the lumen of a vein comparatively
Larger than the arteries
Which muscles are veins often found near??
Active skeletal muscles
What is the purpose of veins being located near active skeletal muscles??
As the muscle contracts the vein is squeezed and blood is moved towards the heart
What is the purpose of Venules??
Link the capillaries and the veins
Structure of venules
Have thin walls
Little smooth muscle
Do arteries contain an outer layer of collagen fibres??
Yes
Do veins contain an outer layer of collagen fibres
Yes
Do capillaries contain an outer layer of collagen fibres??
No
What is the middle layer of elastic fibres and smooth muscle like in the artery
Thick
What is the middle layer of elastic fibres and smooth muscle like in capillaries
Absent
What is the middle layer of elastic fibres and smooth muscle like in veins
Thin
Do arteries have an inner layer
Yes
Do veins have an inner layer
Yes
Do capillaries have an inner layer??
Yes
Does the artery contain valves
No because they are strong and elastic to resist pressure changes as blood is carried at a high pressure
Do capillaries contain valves??
No because here there is an exchange of materials between blood and tissue fluid
Do veins have valves??
Yes because blood is at low pressure as it returns to the heart
Prevents backflow of blood
What is present in the blood?
Red blood cells Platelets White blood cells Urea Oxygen Fats Plasma proteins Proteins
What is present in tissue fluid??
Urea
Oxygen, proteins and fat (but less than in blood)
White blood cells (less than in blood)
What is present in the lymph
White blood cells but less than in blood Urea Oxygen Fats (more than in tissue fluid) Proteins (less than in blood)
Is blood contained in vessels
Yes
Is tissue fluid contained in vessels
No
Is lymph contained in vessels
Yes
What is the pressure like in blood?
Variable
What is the pressure like in tissue fluid??
Variable
What is the pressure like in lymph
Low
Where is tissue fluid found??
Found surrounding body cells
Function of tissue fluid
Transports products and removes waste products
How is tissue fluid formed??
Formed from plasma
What is hydrostatic pressure??
Pressure created by a fluid
What happens to water at the venous ends of the capillary
Water tends to flow back in
What is oncotic pressure??
Something which raises the dilute potential compared to surrounding tissues
What happens to remaining fluid which has been lost from the capillaries
Collected and returned to the blood via the lymph vessels
What is the lymphatic system??
A network of tissues and organs that allow the body to rid of toxins, waste and unwanted materials
What is lymph??
A clear fluid made of white blood cells and fluid from the intestines containing proteins and fats
What cells feature in the blood??
Erythrocytes, leucocytes and platelets
What cells feature in tissue fluid??
Phagocytic white blood cells
What cells feature in lymph
Lymphocytes
Which proteins are found in blood??
Hormones and plasma proteins
What proteins are found in tissue fluid??
Proteins secreted by body cells and some hormones
Are fats transported in the blood??
Some transported as lipoproteins
Are fats transported in tissue fluid??
No
Are fats transported in lymph
More than in blood
Absorbed from lacteals in intestine
Is glucose transported in the blood??
80-120mg per 100ml
Is glucose transported in tissue fluid??
Less than blood
Absorbed by body cells
Is glucose transported in lymph
Less than in blood
Two advantages of keeping blood inside blood vessels
Maintain higher blood pressure
Increase the rate of flow
Where is plasma found
Blood
Where is tissue fluid
Found surrounding cells
Where is lymph found
Vessels
What creates the high hydrostatic pressure at the arterial end of the capillary
Heart beat
Molecules that leave the plasma at the arterial end pass out due to the pressure through what structures??
Fenestrations
What process do molecules leave or enter the cells from tissue fluid??
Diffusion or osmosis if water
What % of tissue fluid enters the lymphatic vessel??
10%
Where does lymph enter back into the blood??
Subclavian vein
What is the hydrostatic pressure of arterial blood?
High
What is the hydrostatic pressure of tissue fluid??
Low
What is the hydrostatic pressure of lymph
Low
Is there presence of large proteins in arterial blood
Yes
Is there presence of large proteins in tissue fluid
No
Is there presence of large proteins in lymph??
No
Is there presence of phagocytes in arterial blood
Yes
Is there presence of Phagocytes in tissue fluid??
Yes
Is there presence of phagocytes in lymph??
Yes
Is there presence of red blood cells in arterial blood??
Yes
Is there presence of red blood cells in tissue fluid
No
Is there presence of red blood cells in lymph
No
How is blood in veins returned to the heart??
As skeletal muscles move
Squeeze veins running through them
Blood pushed through one way valves
Valves then close to present backflow
Why is having a double circulatory system is advantageous to a mammal
Causes a higher blood pressure so metabolites reach tissues faster giving the mammal faster metabolic processes
Describe to role of blood capillaries
Site of the transfer of oxygen and other nutrients from the blood stream to other tissues in the body
Explain how capillaries are able to carry out their function efficiently
They are made up of a single layer of endothelial cells one cell thick
They have short diffusion distance
Spaces between the cells allow components of the blood to escape
Red blood cells are similar in diameter to the capillary
Large SA for exchange
4 ways in which arteries differ in structure from veins
- Arteries have a thick middle layer of elastic fibres and smooth muscle
- Arteries do not contain valves wheras veins do
- Veins have thin walls
- Artery has a small lumen than the vein
When pressure fluctuates as the blood flows along the aorta what causes the fluctuation??
Contraction in the systole causes an increase in blood pressure
Causes relaxation in the diastole which decreases in pressure
State the term used to describe number of fluctuations per minute
Heart rate
Describe the pressure changes in the blood as it flows through the circulatory system from the aorta to the veins
Pressure drops as distance from the heart increases
No fluctuations in the capillaries and veins
Blood pressure does not change in the veins
In the capillaries there is a gradual decrease in pressure
What causes the change in pressure as blood flows from the aorta to the arteries and from arteries to capillaries
The total cross sectional area of the capillaries and arteries is much greater than the aorta so a large drop in pressure is seen here
How many haemoglobin molecules in a single red blood cell??
270 million
What is haemoglobin
A complex protein with 4 subunits
What does the subunit of haemoglobin consist of??
A polypeptide chain and a haem group
What is the haem group of haemoglobin
Contains a single ion in the form of Fe2+
How many oxygen molecules can one haem group of haemoglobin hold??
One
What happens to haemoglobin when it is oxygenated??
Becomes oxyhaemoglobin
What alters the ability of haemoglobin to take up and release oxygen
The amount of oxygen in surrounding tissues
What is the relationship between the amount of oxygen absorbed into the liquid and the oxygen tension in the surrounding air
Directly proportionate
What allows lung tissue to have a high pO2
Ventilation
What happens at low pO2
Oxygen dissociates from oxyhaemoglobin and can diffuse into respiring cells
What happens as pO2 rises??
Diffusion gradient increases and so eventually one oxygen molecule diffuses into the haemoglobin molecule and associates
What is conformal change??
A change in shape of haemoglobin molecules
