Module 9: Immunity and Disease
* Define pathogen:
A pathogen is a disease-causing microorganism such as bacteria, viruses, fungi, or parasites.
* Know the difference between innate and adaptive immunity:
Innate immunity is the body's immediate, non-specific defense against pathogens, while adaptive immunity is slower and specific, involving memory cells for a faster response upon re-exposure.
* Describe how our external innate defenses protect us from infection:
Skin, mucous membranes, and secretions like saliva, tears, and stomach acid act as barriers to prevent pathogens from entering the body.
* Functions of internal innate defense cells:
Phagocytic cells (like macrophages and neutrophils) engulf and destroy pathogens; natural killer (NK) cells destroy infected or cancerous cells by triggering apoptosis.
* What are interferons:
Interferons are proteins produced by virus-infected cells that help nearby cells resist viral infection.
* Major steps of the inflammatory response and its function:
1. Injury or infection triggers release of histamine
2. Blood vessels dilate and become permeable
3. Phagocytes migrate to the area
4. Pathogens are destroyed and tissue repair begins
Function: isolates and eliminates pathogens and begins healing.
* Define histamine:
A chemical released by mast cells that causes vasodilation and increased vessel permeability during inflammation.
* 2 main functions of the lymphatic system:
1. Return excess fluid to the bloodstream
2. Defend the body against infection
* Define lymphocyte:
A type of white blood cell involved in adaptive immunity, including B cells and T cells.
* Describe antigens and antibodies:
Antigens are molecules on pathogens that trigger an immune response; antibodies are proteins made by B cells that bind to specific antigens to neutralize them.
* Define clonal selection, effector cells, and memory cells:
Clonal selection: process by which lymphocytes multiply in response to an antigen
Effector cells: short-lived, attack pathogens
Memory cells: long-lived, provide immunity
* Difference between primary and secondary immune response:
Primary: slow and weak response upon first exposure
Secondary: faster and stronger due to memory cells
* Humoral immune response (B cell response):
B cells produce antibodies that circulate in blood and lymph, targeting pathogens outside cells.
* Cell-mediated immune response (T cell response):
Cytotoxic T cells destroy infected body cells; helper T cells activate other immune cells.
* What are perforin proteins:
Proteins released by cytotoxic T cells that form pores in infected cells, leading to cell death.
* 2 stages of how allergies develop:
1. Sensitization: allergen triggers antibody production
2. Re-exposure: allergen binds antibodies, causing histamine release and symptoms
* Define autoimmune disease and immunodeficiency disease, with examples:
Autoimmune: immune system attacks body (e.g., lupus)
Immunodeficiency: weakened immune system (e.g., AIDS)
* HIV and AIDS, and what cells HIV affects:
HIV is a virus that targets helper T cells; AIDS is the condition caused by severe loss of these cells, leading to immune failure.
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Module 10: The Endocrine System
* What is the endocrine system:
A system of glands that produce hormones to regulate body functions.
* Define hormones and how they are transported:
Hormones are chemical messengers carried in the bloodstream to target organs.
* Define target cell:
A cell with receptors specific to a particular hormone.
* Difference between lipid-soluble and water-soluble hormones:
Lipid-soluble: pass through membranes, bind receptors inside the cell
Water-soluble: bind to receptors on the cell surface
* Location and role of hypothalamus:
Located in the brain; connects nervous and endocrine systems, controls pituitary gland.
* How the hypothalamus controls the pituitary:
Releases hormones that stimulate or inhibit the pituitary's release of hormones.
* Examples of pituitary hormones:
Posterior: ADH, oxytocin
Anterior: GH, TSH, ACTH, LH, FSH, prolactin
* Human growth hormone (HGH):
Stimulates growth, cell reproduction, and regeneration.
* Functions of thyroid gland and hormone:
Controls metabolism, heart rate, and temperature.
* Chemical necessary for thyroid function:
Iodine
* Define antagonistic hormones:
Hormones that have opposite effects, like insulin and glucagon.
* 2 hormones maintaining calcium homeostasis:
Calcitonin (lowers calcium), parathyroid hormone (raises calcium)
* Negative feedback loop for glucose homeostasis and hormones involved:
High blood sugar → insulin released
Low blood sugar → glucagon released
* Adrenal medulla and short-term stress response:
Releases adrenaline and noradrenaline → increased heart rate, energy boost
* Adrenal cortex and long-term stress response:
Releases cortisol → increased glucose, suppressed immune system
* Male and female gonads:
Testes and ovaries
* 3 categories of sex hormones (present in both sexes):
Androgens, estrogens, progestins
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Module 11: Reproduction
* Sexual vs. asexual reproduction + advantages:
Sexual: genetic diversity
Asexual: fast, doesn't need a mate
* External vs. internal reproduction in animals:
External: amphibians, fish
Internal: mammals, birds
* Sperm pathway:
Testes → epididymis → vas deferens → ejaculatory duct → urethra → out of body
* Oocyte pathway:
Ovary → fallopian tube → uterus → cervix → vagina → out of body
* Where fertilization occurs:
Fallopian tube
* Where and when embryo implants:
In the uterus, about 6–10 days after fertilization
* Spermatogenesis and timing:
Production of sperm in testes; begins at puberty
* Oogenesis and timing:
Egg development begins before birth; meiosis II completed at fertilization
* Ovarian cycle, ovulation, hormone peaks:
Follicular phase → ovulation (day 14) → luteal phase
Estrogen peaks before ovulation, progesterone after
LH and FSH peak at ovulation
* Role of LH:
Triggers ovulation
* Define menstruation:
Shedding of uterine lining if no fertilization occurs
* Types of contraception:
Oral contraceptives: block ovulation
IUD: prevents implantation
Vasectomy: cuts sperm path
* Common STD types:
Bacterial: chlamydia, gonorrhea
Viral: herpes, HPV (often incurable)
Fungal: yeast infections
* How STDs impact fertility:
Can cause scarring, blockages, and damage to reproductive organs
* 5 stages of fertilization:
1. Contact
2. Acrosomal reaction
3. Fusion
4. Nucleus entry
5. Zygote formation
* Embryo development: cleavage and gastrula:
Cleavage: rapid cell division
Gastrula: three-layered embryo formed
* Define gestation:
The period of development from fertilization to birth
* Role of placenta:
Provides nutrients, removes waste, and exchanges gases
* Why programmed cell death is important:
Shapes organs and removes unneeded structures (e.g., webbed fingers)
* Trimester sex can be identified via ultrasound:
First trimester, around 12 weeks
* 3 stages of labor:
1. Dilation
2. Expulsion
3. Delivery of placenta
* Hormone key for labor:
Oxytocin
* What is In Vitro Fertilization (IVF):
Egg and sperm are combined outside the body, then implanted in uterus
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Module 12: Nervous System
* Define neuron:
A nerve cell that transmits electrical signals
* Neuron structures and functions:
Dendrites: receive signals
Axon: sends signals
Cell body: processes info
Myelin sheath: speeds signal
* How an action potential begins and travels:
Stimulus opens sodium channels → depolarization → impulse travels down axon
* How intensity is relayed:
More frequent action potentials = stronger stimulus
* Define synaptic cleft:
The gap between two neurons at a synapse
* How neurons communicate across synaptic cleft:
Neurotransmitters are released and bind to receptors on the next neuron
* Effects of substances on neurotransmitters:
Caffeine: blocks adenosine
Alcohol: enhances GABA
SSRIs: block serotonin reuptake
Heroin: mimics endorphins
* Structures of CNS:
Brain and spinal cord
* Define cerebrospinal fluid:
Fluid that cushions and protects the brain and spinal cord
* Peripheral nervous system roles:
Sends sensory info to CNS; carries motor commands from CNS
* Parasympathetic vs. sympathetic:
Parasympathetic: rest and digest
Sympathetic: fight or flight
* Cerebrum, cerebral cortex, corpus callosum:
Cerebrum: thinking
Cortex: outer layer, complex functions
Corpus callosum: connects hemispheres
* Cerebellum function:
Coordinates movement and balance
* Describe sensory transduction:
Conversion of a physical stimulus to an electrical signal
* 5 types of sensory receptors:
1. Mechanoreceptors – touch
2. Thermoreceptors – temperature
3. Pain receptors – injury
4. Chemoreceptors – chemicals
5. Photoreceptors – light
* Rod vs. cone receptors:
Rods: low light, no color
Cones: color, bright light; humans have 3 types
* How ear converts sound:
Eardrum vibrates → middle ear bones → cochlea fluid → hair cells signal brain
* Functions of skeletal system:
Support, protection, movement, blood cell production, mineral storage
* How skeletal muscles attach:
Via tendons to bones
* Sliding-filament model:
Myosin heads pull actin filaments, shortening sarcomeres for contraction
* Define sarcomere:
The basic unit of a muscle fiber is responsible for contraction