Human transport Flashcards
What does blood contains?
Blood is a fluid tissue , made up of plasma , red blood cells , white blood cells and platelets.
Functions of blood
1.It acts as a transport medium carrying various substances from one part of the body to another.
2.Protects the body against pathogens
3.Blood clotting or agglutination at wounds prevents excessive loss of blood and seals the would to prevent any bacteria to enter the bloodstream,.
Function of the plasma
To transport essential materials to the cells and remove waste products from the cells.
Function of red blood cells
To Transport oxygen to cells in the body
Adaptations of the red blood cells
1.Filled with haemoglobin as it combines or oxygen to form oxyhaemoglobin to enable rbc to transport oxygen from lungs to the rest of the body.
2.Absence of nucleus which enable rbc to carry more haemoglobin and more oxygen
3.Biconcave shape which increase surface area to volume ratio and also allows quick of diffusion of oxygen in and out of the cell.
4.Elastic to be able to squeeze through small capillaries to ensure oxygen is transported to all tissues
How does carbon monoxide affects the amount of oxygen carried by blood
Carbon monoxide binds more tightly to haemoglobin than oxygen. It is almost irreversible therefore, if haemoglobin binds to CO , it cannot be used thus less haemoglobin would be available to bind with oxygen.
The main white blood cells
Leucocytes and phagocytes
Differences between phagocytes and lymphocytes
Phagocytes contains a lobed nucleus ,either granular or non-granular cytoplasm , doesn’t produce antibodies, engulf foreign particles by phagocytosis and produced by bone marrow.
However , lymphocytes contains large rounded nucleus , non-granular cytoplasm or small amounts of non-granular cytoplasm, produces antibodies against microorganisms and produced by lymph nodes or bone marrow.
Definition of phagocytosis
The process of engulfing and ingesting foreign particles by phagocytes.
How are antibodies produced
When pathogens enter the bloodstream , they stimulate lymphocytes to produce antibodies or by vaccination to expose the person to a weakened to a weaken form of the pathogen.
Function of platelets
Helps in clotting of blood to seal wounds to prevent excessive bleeding and prevent foreign particles from entering the blood.
How are blood clots formed
When an injury is sustained , the injuried tissue activates platelets .Platelets secrete thrombokinase , which converts prothrombin to thrombin.The enzyme thrombin then converts soluble fibrinogen to fibrin.The presence of calcium is required for the conversion to take place.Long fibrin threads form across the site of injury and trap blood class , forming a blood clot.
Why do arteries have thick muscular walls
The arteries transport blood from the heart to the rest of the body, which is usually under very high pressure , hence they require a thick elastic layer to withstand high pressure.Which allows the arteries to stretch under the high pressure and also provide elastic recoil force that pushes blood out of the arteries to other parts of the body.
Differences in terms of features of arteries and veins
Arteries have thick , muscular walls to support blood coming from heart which is higher in pressure. Contains a small lumen.
On the other hand , veins have thinner walls with less elastic tissue as flow of blood is slower and hence blood pressure is lower compared to arteries.Contains large lumen.
Roles of muscle fibres in arteries
To allow the muscles to construct and dilate , changing diameter of the of the blood vessels , asked on condition of the body. Constriction increases resistance to blood flow hence tends to increase blood pressure and reduce rate of blood flow in arteries.Meanwhile, dilation causes a decrease in resistance and hence decrease in blood pressure and rate of blood flow increases.
Feature of veins and its function
Contains valves to prevent back flow of blood
Features of capillary
It is one-cell thick.It is the largest lumen relative to diameter.Capillary network increases surface area and total cross sectional area for more efficient exchange of substances between blood and cells. No valves present.Absent of elastic muscle walls.
How are substances exchanged between capillaries and tissue cells
- Dissolved food substances and oxygen move from blood in blood capillaries to tissue fluid and then into cells via diffusion.
2.Waste products are released by cells into the tissue of fluid by diffusion and through the capillary walls inti blood and carried to excretory organs for removal.
Definition of double circulation
The passing of blood through the heart being twice as blood moves from the pulmonary circulation (lungs to heart) to the systemic circulation(heart to rest of the body).
Advantages of double circulation
Blood enters the pulmonary circulation (from alveoli to bloodstream) at a low pressure , ensuring sufficient time for diffusion of oxygen into blood.
Blood is then pumped into the systemic circulation at high pressure from the bloodstream into cells , ensuring oxygenated blood is quickly distributed to all tissues in the body.
Reasons for the thin walls of Atria (both atriums)
To force blood into the ventricles
Reasons for different thickness of each ventricle
Right ventricle has relatively thick muscular walls to move into pulmonary circulation while Left ventricle has even thicker walls to pump blood into the systemic circulation .
Systole and Diastole
Systole = Contraction
Diastole = Relaxation
‘Lub’ and ‘Dub’
The ‘lub’ sound is caused by the closure of the bicuspid and tricuspid valve.
The ‘dub’ sound is caused by the closure of the semi-lunar valve.
