T11 Flashcards
1
Q
Cells of immune system
A
- Phagocytes (neutrophils & macrophages)
2. Lymphocytes
2
Q
Phagocytes
A
- Produced in bone marrow (myeloid stem cells), stored there before being distributed through blood
- Neutrophils (lobed nuclei)
- Macrophages
3
Q
Neutrophils (lobed nuclei)
A
- Travel throughout body
- Can leave blood by squeezing through capillary walls to patrol tissues
- Short-lived
4
Q
Macrophages
A
- Larger than neutrophils
- Found in organs such as lungs, liver, spleen, kidney, lymph nodes
- Made in bone marrow, travel in blood as monocytes
- Long-lived
- Cut up pathogens to display antigens to be recognized by lymphocytes
5
Q
Phagocytosis
A
- Cells under attack release chemical called histamine, attracting passing neutrophils
- Neutrophils moves towards pathogen, which may be clustered together and covered with antibodies
- Antibodies further stimulate the neutrophil to attack pathogens
- This is because neutrophils have receptor proteins on surfaces that recognise antibody molecules and attach to them
- When neutrophils attaches to pathogen, neutrophils membrane engulfs pathogen, and traps it in a phagocytic vacuole (endocytosis)
- Digestive enzymes secreted into phagocytic vacuole to destroy pathogen
- After killing and digesting pathogens, neutrophil dies
- Dead neutrophils often collect at infection site to form pus
6
Q
Lymphocytes
A
- Smaller than phagocytes, large nucleus
2. Produced in bone marrow (lymphoid stem cells)
7
Q
B- lymphocytes
A
- Spread throughout body, concentrating in lymph nodes & spleen
- Become plasma & memory cells
8
Q
Maturation of B-lymphocytes
A
- In bone marrow, immature cells divides by mitosis
- Still in bone marrow, each B cells matures
- Mature B cells produce antibody receptors in surface membrane
- Mature B cells circulate & concentrate in liver & spleen
9
Q
Mode of action of B-lymphocytes
A
- a B cell has specific antibodies to antigen
- B cell divides by mitosis, daughter cells become plasma/memory cells
- plasma cells secrete antibodies bind to antigens
- when antigen re-enters body, memory cells produced earlier respond by dividing into plasma cells and more memory cells;  Second response is faster than first due to memory cells.
10
Q
Antibodies
A
- globular glycoproteins with quaternary structure 
- form groups of plasma proteins called immunoglobulins
- Consists of four polypeptide chains (two long/ heavy-chains; too short/light chains)
- disulphide bonds hold chains together
- variable region of one light in one heavy-chain make antigen binding sites
- hinge region between 2 heavy chains give flexibility in binding to antigen
- heavy chains have chain of sugar molecules attached to them
11
Q
Function of antibodies
A
- Combine with virus/toxins
- Attach to bacteria flagella
- Cause agglutination of bacteria
- Coat bacteria, makes it easier for phagocytes to ingest them
12
Q
T-lymphocytes
A
- Created in bone marrow, and collect in thymus when mature
1. Helper & killer T cells
13
Q
Maturation of T-lymphocytes
A
- in bone marrow, immature T cells divide by mitosis
- in thymus, each T cells matures
- T cell produce receptors in cell-surface membrane
- mature T cells circulate as helpers/killers
14
Q
Mode of action of T-lymphocytes
A
- helper/killer T cells bind to antigens of infected body cells
- helper/killer cells divide by mitosis
- helper T cells wither :
- divide into memory cells
- Secrete cytokines that stimulate B cells to divide and form plasma/memory cells
- killer T cells either :
- divide into memory cells
- find holes in cell surface membrane of infected body cells and secrete toxic substances to kill body cell and pathogen inside
15
Q
Helper T Cells
A
Either
- Divide into memory cells
- Secretes cytokines that stimulate B cells to divide & form plasma/memory cells
