6.3 - Defence Against Infectious Diseases Flashcards
1
Q
Name 7 methods of skin/body protection
A
Tears Saliva Skin Large intestine Bladder Stomach Respiratory tract
2
Q
Tears
A
Wash away irritants and microbes, lysosome kills bacteria
3
Q
Saliva
A
Washes microbes from the mouth and teeth
4
Q
Skin
A
Physical barrier
Acidic pH discourages growth
5
Q
Large intestine
A
Bacterial inhabitants outcompete invaders
6
Q
Bladder
A
Urea washes microbes from the urethra
7
Q
Stomach
A
Acid kills microbes
8
Q
Respiratory tract
A
Mucus traps microbes
Cilia sweep away microbes
9
Q
Phagocytes (5)
A
- white blood cells
- ingest pathogens by endocytosis
- contain lysosomes, which contain digestive enzymes
- identify pathogens by detecting foreign proteins on the pathogen surface
- assisted by antibodies attached to pathogens
10
Q
Phagocytosis (6)
A
- microbe attached to surface of phagocyte (microphage)
- detects it as non-self by antibodies
- ingested by endocytosis
- surrounded by pseudopods
- within, a lysosome secrets digestive enzymes which breaks down the microbes (now inside a phagosome)
- waste material produced then ejected by exocytosis
11
Q
Blood clotting (2)
A
- needs to happen incredibly rapidly at the right time, in a controlled way
- helps to prevent entry of microorganisms
- blood contains a soluble protein called fibrinogen
12
Q
Blood clotting steps (7)
A
- Process of clotting converts soluble fibrinogen into insoluble fibrin
- Chemicals released by damaged cells or clotting factors released by platelets initiate a cascade of enzyme catalysed reactions
- Eventually leads to prothrombin (inactive enzyme) being converted into thrombin (active enzyme)
- Thrombin converts fibrinogen into fibrin
- Fibrin forms a mesh, trapping blood cells into a clot
- External and internal clots prevent blood loss
- Clot dries and forms a scab
13
Q
How does HIV cause AIDS? (7)
A
- Virus inserts RNA into specific lymphocyte called a helper T-cell
- Enzyme reverse transcriptase makes copies of genes in form of DNA
- Helper T-cell uses DNA to produce more viruses
- Viruses destroy helper T-cells
- Knock-on effect on B-cells, decrease in number and produce fewer antibodies
- Lack of antibodies means infection cannot be fought (AIDS)
- Infected individual cannot fight off pathogens
14
Q
Transmission of HIV (7)
Hint: BOB DUCA
A
B reast feeding
O ral sex
B lood transfusion
D uring birth
U nprotected sexual intercourse
C ontaminated needles
A cross placenta
15
Q
Antibiotics (4)
A
- Act against specific chemicals or chemical pathways in prokaryotes, do not affect eukaryotes
- Target these processes: translation, replication, transcription, ribosome function, cell wall formation
- Some bacteria have evolved genes that confer resistance to specific antibiotics or multiple antibiotic resistance
- EG: penicillin
