module 3 - 8.3 blood, tissue fluid and lymph Flashcards
what is blood?
specialised transport medium that is also a connective liquid tissue
what are the functions of blood?
- transport
- defence (immune system)
- thermoregulation
- maintaining pH of bodily fluids
what are erythrocytes?
red blood cells
what are platelets?
fragments of large megakaryocytes found in bone marrow, also involved in blood clotting
what are leucocytes?
white blood cells (e.g. lymphocytes and phagocytes)
what is unusual about human red blood cells?
they have no nucleus, they are packed with mRNA and ribosomes to make proteins
what are the adaptations of human red blood cells?
flattened biconcave disc shape - large SA:V for efficient gas exchange
large amount of haemoglobin - for transporting oxygen
no nucleus or organelles - maximises space for Hb so more oxygen is transported
what does 8% of blood plasma consist of?
plasma proteins (half are a group of proteins called ALBUMINS)
what are albumins?
water soluble transport proteins that carry molecules and ions in the blood
what is the function of albumins?
regulates osmotic pressure of blood (done by proteins so is called oncotic pressure - albumins displace water molecules)
how do albumins cause dipoles?
they have a hydrophilic R group which means they can then hydrogen bond with water
the typical human blood oncotic pressure is negative, what does this create?
a tendency for water to move into the blood from surrounding tissue by osmosis
what is the blood pressure developed by the contraction of the heart?
high
what is the pressure developed by the contraction of the heart called?
hydrostatic pressure
what happens at the arteriole end of the capillary bed when hydrostatic pressure has fallen to +4.6kPa?
fluid is forced out the capillaries by the higher pressure in the blood, creates TISSUE FLUID
what happens at the venule end of the capillary bed?
oncotic pressure is higher and acts in opposite direction so water moves back into capillaries
is there a change in oncotic pressure at anytime?
no it stays the same all the time
how is tissue fluid similar to blood plasma?
its the same but just without red blood cells and plasma proteins
how does water go back into the blood?
by osmosis, otherwise blood would dry out
what is the pressure difference between arterial and venous end of capillaries?
venous end has lower hydrostatic pressure than arterial end, due to friction
what is the lymphatic system?
secondary circulatory system and major part of the immune system, complementary to cardiovascular system
what are lymphatic capillaries?
vein-like lymph vessels containing valves
what are lymph nodes?
sac-like organs that trap pathogens/ foreign substances that contain large number of white blood cells
what is lymphatic tissue?
found in the spleen, thymus and tonsils - contains large amounts of white blood cells and is involved in their development
what happens to the 10% of tissue fluid that is not returned to the blood?
flows into blind-ended lymph capillaries forming lymph
what is lymph?
similar to plasma and tissue fluid but has less oxygen and nutrients and more fatty acids
how is lymphatic fluid moved?
by body movements squeezing on lymph capillaries and vessels aided by one-way valves
what does the flow of lymph along the thoracic duct cause?
a large lymph vessel to drain the subclavicle vein
what is oedema?
build up of tissue fluid (caused by problems within the lymphatic system)
what do phagocytes and lymphocytes do?
filter out bacteria using phagocytes in the lymph nodes
