Lymphatic system – formation of lymph and its functions. Thymus. Functions of the spleen

Question 1

formation of lymph

Answer 1

blood plasma is full of nutrients and oxygen

hydrostatic pressure pulls fluid from circulatory system into the interstitial space where it reaches tissues

colloid osmotic/ oncotic pressure pulls fluid from interstitial space back into circulatory system helped by albumin

some fluid is left over called lymph collected by lymph capillaries with 1 way valves -> water/ proteins/ lipids/ WBCs

lymph ducts -> v. subclavii -> bloodstream

Question 2

lymph - function 1

Answer 2

works with colloid osmotic pressure + hydrostatic pressure to prevents edema

Question 3

lymph function 2

Answer 3

lymph capillaries in small intestine called lacteals

• absorbs dietary fats + water soluble vitamins
• absorbed as chyle to bloodstream

Question 4

lymph function 3

Answer 4

lymph nodes
- filtration sites with lymphocytes for immune response

Question 5

thymus list

Answer 5

structure
location
functions

Question 6

thymus - structure

Answer 6

small bilobular lymphatic organ
- x1 cortex
- x1 medulla

Question 7

thymus - location

Answer 7

upper anterior quadrant of chest
behind sternum
between lungs

Question 8

thymus - function 1

Answer 8

T CELL MATURATION

immature T cells are called thymocytes that come from hematopoietic stem cells

they migrate to thymus for maturation

thymic cortex
- cells undergoes positive selection to recognise self MHC
- cells that fail this = apoptosis

thymic medulla
- cells that react too strongly to self antigens are eliminated
- prevent autoimmune disease
- tolerating cells enter peripheral circulation to mature into desired T cell

Question 9

thymus - function 2

Answer 9

HORMONAL FUNCTIONS

thymyosin/ thymopoietin/ thymulin
= help differentiation + maturation of T cells

Question 10

thymus - function 3

Answer 10

thymus undergoes involution where its structure/function shrinks with age to be replaced with adipose tissue

Question 11

spleen list

Answer 11

structure
functions

Question 12

spleen structure 1

Answer 12

red pulp
- sinusoids filled with blood

Question 13

spleen structure 2

Answer 13

white pulp
- lymphoid tissue with WBC

Question 14

spleen structure 3

Answer 14

marginal zone
- inbetween red + white pulp
- with macrophages + B cells kill blood born antigens

Question 15

spleen - function 1

Answer 15

red pulp of spleen involved
- removing dead RBCs
- removal of pathogens by macrophagic phagocytosis

Question 16

spleen - function 2

Answer 16

white pulp of spleen involved in immune response due to lots of lymphocytes to produce B cells for antibody production

Question 17

spleen - function 3

Answer 17

spleen can store blood and release during lack of blood = haemorrhage

Question 18

spleen - function 4

Answer 18

hematopoesis = production of RBCs during fetal development