Module 9: Immunity and Disease

Pathogens

• Disease-causing microorganisms: bacteria, viruses, fungi, parasites.

Innate vs. Adaptive Immunity

• Innate Immunity: Immediate, non-specific defense against pathogens.
• Adaptive Immunity: Slower, specific response with memory cells for faster re-exposure response.

External Innate Defenses

• Barriers: Skin, mucous membranes, secretions (saliva, tears, stomach acid).

Internal Innate Defense Cells

• Phagocytic Cells: Macrophages and neutrophils engulf/destroy pathogens.
• Natural Killer (NK) Cells: Destroy infected/cancerous cells via apoptosis.

Interferons

• Proteins from virus-infected cells helping nearby cells resist infection.

Inflammatory Response

1. Injury/infection triggers histamine release.
2. Blood vessels dilate, become permeable.
3. Phagocytes migrate to the area.
4. Pathogens destroyed, tissue repair begins.

• Function: Isolate/eliminate pathogens and initiate healing.

Histamine

• Chemical from mast cells causing vasodilation and vessel permeability during inflammation.

Lymphatic System Functions

1. Return excess fluid to the bloodstream.
2. Defend the body against infection.

Lymphocytes

• White blood cells in adaptive immunity: B cells and T cells.

Antigens and Antibodies

• Antigens: Molecules on pathogens triggering immune response.
• Antibodies: Proteins by B cells binding to antigens for neutralization.

Clonal Selection, Effector Cells, Memory Cells

• Clonal Selection: Lymphocyte multiplication in response to antigen.
• Effector Cells: Short-lived, pathogen-attacking.
• Memory Cells: Long-lived, provide immunity.

Primary vs. Secondary Immune Response

• Primary: Slow/weak on first exposure.
• Secondary: Faster/stronger due to memory cells.

Humoral vs. Cell-Mediated Immune Response

• Humoral (B cell): Antibodies in blood/lymph target extracellular pathogens.
• Cell-Mediated (T cell): Cytotoxic T cells destroy infected cells; helper T cells activate immune cells.

Perforin Proteins

• Released by cytotoxic T cells to form pores in infected cells, leading to cell death.

Allergies Development

1. Sensitization: Allergen triggers antibody production.
2. Re-exposure: Allergen binds antibodies, causing histamine release/symptoms.

Autoimmune vs. Immunodeficiency Diseases

• Autoimmune: Immune system attacks body (e.g., lupus).
• Immunodeficiency: Weakened immune system (e.g., AIDS).

HIV and AIDS

• HIV: Virus targeting helper T cells.
• AIDS: Condition from severe T cell loss causing immune failure.

Module 10: The Endocrine System

The Endocrine System

• Glands producing hormones to regulate body functions.

Hormones

• Chemical messengers in the bloodstream targeting specific organs.

Target Cells

• Cells with receptors specific to a hormone.

Lipid-Soluble vs. Water-Soluble Hormones

• Lipid-Soluble: Pass through membranes, bind inside cell.
• Water-Soluble: Bind to receptors on cell surface.

Hypothalamus

• Brain-based; connects nervous/endocrine systems, controls pituitary gland.

Hypothalamus and Pituitary Control

• Releases hormones to stimulate/inhibit pituitary hormone release.

Pituitary Hormones

• Posterior: ADH, oxytocin.
• Anterior: GH, TSH, ACTH, LH, FSH, prolactin.

Human Growth Hormone (HGH)

• Stimulates growth, cell reproduction, and regeneration.

Thyroid Gland and Hormone

• Controls metabolism, heart rate, temperature.
• Chemical: Iodine necessary for function.

Antagonistic Hormones

• Hormones with opposite effects (e.g., insulin and glucagon).

Calcium Homeostasis Hormones

• Calcitonin: Lowers calcium.
• Parathyroid Hormone: Raises calcium.

Glucose Homeostasis

• High Blood Sugar: Insulin released.
• Low Blood Sugar: Glucagon released.

Adrenal Glands

• Medulla: Short-term stress response (adrenaline/noradrenaline).
• Cortex: Long-term stress response (cortisol).

Gonads

• Male: Testes.
• Female: Ovaries.

Sex Hormones

• Categories: Androgens, estrogens, progestins.

Module 11: Reproduction

Reproduction Types

• Sexual: Genetic diversity.
• Asexual: Fast, no mate needed.

Reproduction Types in Animals

• External: Amphibians, fish.
• Internal: Mammals, birds.

Sperm Pathway

• Testes → epididymis → vas deferens → ejaculatory duct → urethra → out.

Oocyte Pathway

• Ovary → fallopian tube → uterus → cervix → vagina → out.

Fertilization and Embryo Implantation

• Fertilization: Occurs in fallopian tube.
• Implantation: Uterus, 6–10 days post-fertilization.

Spermatogenesis and Oogenesis

• Spermatogenesis: Sperm production starts at puberty.
• Oogenesis: Egg development begins pre-birth; meiosis II at fertilization.

Ovarian Cycle

• Follicular phase → ovulation (day 14) → luteal phase.
• Hormones: Estrogen peaks pre-ovulation, progesterone post.
• LH and FSH: Peak at ovulation.

Menstruation

• Shedding of uterine lining if no fertilization.

Contraception Types

• Oral: Blocks ovulation.
• IUD: Prevents implantation.
• Vasectomy: Cuts sperm path.

Common STDs

• Bacterial: Chlamydia, gonorrhea.
• Viral: Herpes, HPV (often incurable).
• Fungal: Yeast infections.

STDs and Fertility

• Cause scarring, blockages, damage reproductive organs.

Fertilization Stages

1. Contact.
2. Acrosomal reaction.
3. Fusion.
4. Nucleus entry.
5. Zygote formation.

Embryo Development

• Cleavage: Rapid cell division.
• Gastrula: Three-layered embryo formation.

Gestation

• Period from fertilization to birth.

Placenta Role

• Nutrient provision, waste removal, gas exchange.

Programmed Cell Death

• Shapes organs, removes unneeded structures (e.g., webbed fingers).

Sex Identification via Ultrasound

• First trimester, around 12 weeks.

Labor Stages

1. Dilation.
2. Expulsion.
3. Delivery of placenta.

• Key Hormone: Oxytocin.

In Vitro Fertilization (IVF)

• Egg and sperm combined outside body, implanted in uterus.

Module 12: Nervous System

Neurons

• Nerve cells transmitting electrical signals.

Neuron Structures

• Dendrites: Receive signals.
• Axon: Sends signals.
• Cell Body: Processes information.
• Myelin Sheath: Speeds signal transmission.

Action Potential

• Begins/Travels: Stimulus opens sodium channels → depolarization → impulse travels down axon.

Intensity Relaying

• More frequent action potentials indicate stronger stimulus.

Synaptic Cleft

• Gap between two neurons at a synapse.

Neuron Communication

• Neurotransmitters released, bind to receptors on next neuron.

Substance Effects on Neurotransmitters

• Caffeine: Blocks adenosine.
• Alcohol: Enhances GABA.
• SSRIs: Block serotonin reuptake.
• Heroin: Mimics endorphins.

CNS Structures

• Brain and spinal cord.

Cerebrospinal Fluid

• Cushions/protects brain and spinal cord.

Peripheral Nervous System Roles

• Sends sensory info to CNS; carries motor commands from CNS.

Autonomic Nervous System

• Parasympathetic: Rest and digest.
• Sympathetic: Fight or flight.

CNS Components

• Cerebrum: Thinking.
• Cortex: Outer layer, complex functions.
• Corpus Callosum: Connects hemispheres.

Cerebellum

• Coordinates movement/balance.

Sensory Transduction

• Conversion of physical stimulus to electrical signal.

Sensory Receptors

1. Mechanoreceptors: Touch.
2. Thermoreceptors: Temperature.
3. Pain Receptors: Injury.
4. Chemoreceptors: Chemicals.
5. Photoreceptors: Light.

Rods vs. Cones

• Rods: Low light, no color.
• Cones: Color, bright light; humans have three types.

Ear and Sound Conversion

• Eardrum → middle ear bones → cochlea fluid → hair cells signal brain.

Skeletal System Functions

• Support, protection, movement, blood cell production, mineral storage.

Skeletal Muscle Attachment

• Via tendons to bones.

Sliding-Filament Model

• Myosin heads pull actin filaments, shortening sarcomeres for contraction.

Sarcomere

• Basic muscle fiber unit responsible for contraction.