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Understanding Immunity, Endocrine, and Reproductive Systems

May 4, 2025

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 β†’ epididymis β†’ vas deferens β†’ ejaculatory duct β†’ urethra β†’ out.

Oocyte Pathway

  • Ovary β†’ fallopian tube β†’ uterus β†’ cervix β†’ vagina β†’ 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 β†’ ovulation (day 14) β†’ 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 β†’ depolarization β†’ 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 β†’ middle ear bones β†’ cochlea fluid β†’ 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.