8.3 - Blood,tissue Fluid Amd Lymph Flashcards
What does blood consist of ?
55% plasma
40% water
5% RBC
What does the plasma do in the blood ?
Carries a wide variety of red blood cells , white blood cells and other components such as dissolved glucose,amino acids, mineral ions , hormones and large plasma proteins
What does blood transport ?
- O2 in and CO2 from the respiring cells
- digested food from the small intestine
- nitrogenous waste products from the cells to the excretory organs
- chemical messages ( hormones )
- food molecules from storage compounds to the cells that need them
- platelets to damaged areas
- cells and antibodies involved in the immune response
What other things does the blood contribute too
- maintenance of a steady body temperature
- acts as a buffer minimising pH changes
What does having a positive pressure mean ?
Moving out of the blood
What does having a negative pressure mean ?
Moving into the blood
Name a plasma protein
Albumin
Define hydrostatic pressure
The pressure exerted by a fluid eg. Blood
Define oncotic pressure
- This is the osmotic pressure exerted by plasma proteins within a blood vessel it usually pulls water into the circulatory system
- tendency of water to move into the blood by osmosis
What does how much liquid leaves the plasma to form tissue fluid depend on ?
- hydrostatic pressure
- oncotic pressure
How is tissue formed ?
- blood flows into the capillary at high hydrostatic pressure in the arteriole end
- high pressure forces fluid through the gaps in the cells of the capillary where nutrients and oxygen dissolve into it
- this fluid with the dissolved oxygen and nutrients seep in between the cells of the tissue = tissue fluid
How does fluid return to the blood ?
- the hydrostatic pressure of the blood is pushed back my the hydrostatic pressure of the fluid which pushes the fluid back into the capillaries
- the water potential of the tissue fluid is higher than the blood
- therefore water moves back into the blood from the fluid by osmosis
Where do substances that are dissolved in plasma pass through ?
Fenestrations In the capillary walls except large plasma proteins
What is the osmotic effect ?
Gives the blood in the capillaries a relatively high solute potential and relatively low water potential compared with the surrounding fluid
How many KPa is oncotic pressure ?
-3.3 KPa
Explain what happens as blood flows through arterioles
- Blood flows through the arterioles into the capillaries
- still under pressure from the surge of blood that occurs every time the heart contracts = hydrostatic pressure
What occurs at the arterial end of the capillary ?
- hydrostatic pressure forces the fluid out of the capillaries is relatively high
- higher than the oncotic pressure attracting water in by osmosis = fluid is squeezed out of the capillaries
- this fluid fills the spaces between the cells and is called tissue fluid
What does tissue fluid have the same composition of ?
Plasma but without RBC and plasma proteins
What happens when the blood travels towards the venous end ?
- balance of forces change
- hydrostatic pressure falls to around 2.3KPa in the vessels as fluid has moved out and the pulse is completely lost
- oncotic pressure is still -3.3KPa —> no stronger than the hydrostatic pressure
- water moves back into the capillaries by osmosis as it reaches the venous end
How much of the tissue fluid is reabsorbed back into the blood ?
90%
What is the hydrostatic pressure in KPa ?
4.6 KPa
What is filtration pressure ?
Filtration pressure = hydrostatic pressure - oncotic pressure
How is lymph formed ?
- formed when intercostal fluid comes into contact with the blood
- most fluid leaves the blood vessels and goes into the tissue fluid
- but some goes into the blood vessels whilst the rest enters the lymphatic system
- where it is transported to the veins to mix with the blood and become lymph
How is the fluid transported through the lymph capillaries ?
By squeezing of the body muscles
What prevents the back flow of lymph ?
Valves
What occurs in the lymph nodes ?
- lymphocytes build up in the lymph node when necessary to produce antibodies —> which are then passed into the blood
- lymph nodes intercept bacteria and other debris from the lymph which are ingested by phagocytes found in the nodes
What are enlarged nodes a sign of ?
That the body is fighting off an invading pathogen
Where do doctors often Examine as they are key sites of some major lymph nodes ?
Neck
Armpits
Stomach
Groin
How is a lymphatic system formed ?
Lymph capillaries connect into larger lymph vessels
Why is a water potential gradient formed ?
- proteins remain in the blood as they are too large to pass through the pores in the capillary walls
- increased protein content creates a water potential gradient between the capillary and the tissue fluid
What is oedema ?
- If blood pressure is high ( hypertension ) then the pressure at the arterial end is even greater
- this pushes more fluid out of the capillary and fluid begins to accumulate around the tissues
Describe three ways In which the composition of tissue fluid is different to the composition of plasma
In plasma there is :
- higher concentration of glucose
- higher concentration of fatty acids and glycerol
- higher concentration of amino acid’s
- lower water potential
In tissue fluid there is :
- higher concentration of the substances secreted by cells eg. Insulin
State a difference between tissue fluid and blood
Tissue fluid does not contain plasma proteins such as ALBUMIN as they’re too large to pass through the capillary walls
State the effect of water potential of the blood if the concentration of glucose increases
Water potential decreases
Explain why the oncotic pressure of the blood depends only on the concentration of large plasma proteins
- large plasma proteins cannot pass out through the capillary walls and leave the blood but other solutes are able to
- an imbalance of large plasma proteins between the blood and tissue fluid results in oncotic pressure
Is this statement true or false
Lymph is similar in composition to tissue fluid but has more oxygen
False
Is this statement true or false
Tissue fluid does not contain lymphocytes because they are too large to pass through the capillary wall
False
Is this statement true or false
Lymph contains more protein than tissue fluid because of antibody production by plasma cells
True
