Download Lesson 13 Class Notes I. Pathogens A. Bad bacteria 1. Single

Lesson 13 Class Notes
I.
Pathogens
A. Bad bacteria
1. Single-celled (Kingdom Monera)
2. Multiply quickly
3. Beneficial bacteria on skin and in intestines
B. Fungi
1. Candida
a. Inside everyone but usu. under control
b. Causes itching, rashes, difficulty swallowing
2. Tinea
a. Lives on damp surfaces like locker rooms and showers
b. Causes athlete’s foot- burning, itching rashes
C. Worms
1. Trichinella
a.
found in undercooked pork
b. Causes fever, muscle soreness, swelling, even death
2. Ringworm- contagious fungal infection (see tinea above- not a worm)
3. Tapeworm- flat, segmented worms that live in the intestines
4. Pinworm- white in color and less than half an inch long, infect the intestines
D. Viruses
1. Not really alive- can’t reproduce alone
2. Take control of cell and makes copies of itself using the cell’s resources until cell
explodes and spreads virus
3. i.e. cold, flu, mumps, AIDS
E. Cancer
1. DNA mutation
2. Tumor formed and sometimes cancerous
F. Disease terminology
1. Acute- short-lived, immediate
2. Chronic- long-lasting, overuse
3. Malignant- life-threatening
4. Benign- not significantly harmful
5. Contagious- easily spread
6. Infectious- caused by parasites
II.
The Lymphatic System
A. Process:
1. small amounts of clear fluid (tissue fluid) leak out of capillaries to keep the tissues
moist
2. tissue fluid drains back into lymph vessels (now called lymph)
3. lymph filtered through lymph nodes and sent back to circulatory system
B. Lymph nodes
1. Over five hundred in body; Less than an inch wide; Hard-working bean-shaped filters
2. Found everywhere but clusters in armpits, groin and neck
3. Several vessels bring lymph into node but only one vessel takes lymph out
4. Node contains lymphocytes and macrophages
C. Lymphocytes (found in lymph nodes)
1. Special white blood cell
2. Detect any foreign invader, even cancer cells
3. Invader gets trapped in the lymph node as node makes huge number of
lymphocytes to be sent into bloodstream
4. Macrophages engulf and destroy foreign material
D. Spleen
1. Located in upper left abdomen; size of clenched fist
2. Filters blood and removes millions of dead or damaged rbc every second
3. Stores extra blood
4. Lymphocytes also produced here
E. Thymus
1. Located in chest near the heart
2. Some lymphocytes sent here for special training for spotting and attacking invaders
3. Called T lymphocytes or T cells
III.
Immunity
A. Innate immunity
1. Sebum, tears, mucus and cilia, intestinal bacteria
2. In body at all times and respond in same manner
B. Complement system
1. Proteins in bloodstream activated by foreign bacteria
2. Send out chemicals to attract wbc which cause inflammation
3. Inflammation swells the tissue and directs attention to need
4. Injured tissue sends out histamines which cause capillaries to widen and allow more
blood into area and fluid into surrounding tissues
5. Pus= damaged tissue, living and dead bacteria and dead white blood cells
6. Fever increases chemical activity to help destroy pathogens
C. Adaptive immunity
1. Stem cells make innate white blood cells and special agents:
a. T lymphocytes: T cells form in bone marrow but develop in thymus
b. B lymphocytes: B cells form and develop in bone marrow and live in
bloodstream or lymph nodes/spleen
2. Recognize self and non-self
3. Antigens of virus or cancer cells visible to T cells in cell membrane
4. Antibody action
a. Macrophages eat pathogens but save several antigen “flags”
b. B cells make special proteins called antibodies to grab specific antigen
c. Antibody marks invader for killer T cells
d. B and T cells remember invader to launch rapid, specific, aggressive response
D. Autoimmune diseases
1. def: body forms antibodies against its own tissue
2. allergies: B cells make antibodies against unharmful substances
3. antihistamines block inflammatory action
4. HIV: destroys helper T cells so can’t fight basic illnesses
E.
Achieving immunity
1. Passive immunity
a. immunity passed from mother to child during pregnancy and through mother’s
milk until ~6months old
b. antibody transfer: temporary immunity; not a vaccination (rabies)
2. Acquired immunity
a. immune system is exposed to and responds to specific threat
b. viruses mutate every year so lifelong immunity not possible
F. Active artificial immunity
1. Vaccinations contain killed or weakened pathogens
2. Tetanus, measles, polio, whooping cough, rubella and mumps
G. Antibiotics
1. Normally released from fungi or bacteria to fill surrounding competition
2. Penicillin- comes from mold
3. MRSA- overused antibiotics make the bacteria resistant