Ch. 11. Human Body Systems

Structural Hierarchy

• Cell: Fundamental unit of life.
• Cells → Tissues → Organs → Organ systems → Organism
• Form correlates with function.

Anatomy vs. Physiology

• Anatomy: Study of the structure of body parts (form).
• Physiology: Study of the functions of those parts.

Tissues

• Cells cooperate as part of a tissue.
• Tissue: Similar cells performing a specific function.
• Types: Connective, Epithelial, Nervous, Muscle.
• Connective tissue: Supports, connects, or binds different parts of the body. Cells scattered throughout an extracellular matrix. Examples: Cartilage, blood, bone.
• Epithelial tissue: Covers body surfaces. (e.g., skin, digestive tract).
• Nervous tissue: Communicates signals (brain and body).
• Muscle tissue: Bundles of muscle fibers that contract. Types: Skeletal, smooth, cardiac.

Homeostasis

• Maintaining a constant internal environment.
• Maintained by negative feedback (most common) or positive feedback.

Diabetes: Breakdown in Homeostasis

• Type 1: Body doesn’t produce enough insulin; requires insulin injection.
• Type 2: Cells don’t respond to insulin; controlled by diet and exercise.

Integumentary System

• Skin, hair, nails protect from physical harm.
• Temperature regulation: muscle shivers (heat), fat (insulation), blood vessels adjust (blood flow), sweat glands (evaporative cooling), hair follicle (insulation).

Negative Feedback

• Result of a process inhibits the process.
• Maintains balance.

Positive Feedback

• Results intensify the process.
• Causes rapid, powerful changes (e.g., uterine contractions during birthing).

Food Processing

• Four stages: Ingestion, Digestion (mechanical & chemical), Absorption, Elimination.
• Mechanical digestion: Physical breakdown (e.g., chewing).
• Chemical digestion: Enzymes break bonds (hydrolysis).
• Absorption: Uptake of nutrient molecules (small intestine).
• Elimination: Disposal of undigested matter.

Digestive System

• Alimentary canal: Long tube where food processing occurs.
• Mouth: Ingestion and initial digestion.
• Esophagus: Transports food to the stomach via peristalsis.
• Stomach: Secretes gastric juice (enzymes like pepsin).
• Small intestine: Completes digestion and absorbs nutrients.
• Large intestine (colon): Absorbs water.
• Rectum: Stores feces.
• Anus: Expels waste.
• Accessory organs: Salivary glands, liver, gallbladder, pancreas.

Nutrition

• Food provides energy (ATP) and building materials.
• Essential nutrients: Cannot be produced by the body.
• Categories: minerals, vitamins, essential fatty acids, essential amino acids.

Digestive System Ailments

• Acid reflux, appendicitis, cholera, ulcer.

Improper Diets

• Obesity: High BMI, contributes to type 2 diabetes, cancer, cardiovascular disease.
• Malnutrition: Lack of calories or essential nutrients.
• Eating disorders: Anorexia nervosa and bulimia (nutrient deficiencies).

Gastric Bypass Surgery

• Creates small stomach pouch, bypasses the rest, shortens small intestine.
• Less absorption. Patient feels full faster

Respiratory System

• Exchanges O2 (in) and CO2 (out).
• Breathing: Alternation of inhalation and exhalation.
• Parts: Nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli, diaphragm.

Oxygen Delivery

• Circulatory system conveys O2 from lungs to body cells.
• Oxygen used as final electron receptor. $O<em>2 \rightarrow H</em>2O$

Respiratory System Issues

• Emphysema: From tobacco smoke or air pollution.
• Bronchitis: Viral infection of bronchioles.
• Asthma: Airway inflammation.

Circulatory System

• Transports materials via blood vessels.
• Heart pumps blood.
• Cardiovascular system: Heart and blood vessels.

Blood Vessels

• Arteries: Away from the heart (thickest).
• Veins: To the heart (have valves).
• Capillaries: Exchange materials.

Cardiovascular System Circuits

• Pulmonary: Heart to lungs
• Systemic: Heart to body

Heart

• Atria receive blood, pump to ventricles.
• Ventricles pump blood out.

Cardiac Cycle

• Diastole: Heart muscles relax (low blood pressure).
• Systole: Heart contracts (high blood pressure).

Heartbeat Timing

• Sinoatrial (SA) node: Times heartbeats.
• Atrioventricular (AV) node: Signals ventricles to contract.

Cardiovascular System Issues

• Hypertension: High blood pressure.
• Heart disease: Fatty deposits block arteries.
• Anemia: Blood doesn’t carry enough oxygen.
• Myocardial infarction (heart attack): Blockage of coronary arteries.

Blood Composition

• Plasma: Liquid (55% water, 3% proteins…).
• Cellular elements (44% red blood cells, 1% white blood cells & platelets).
• Red blood cells: Transport O2 using hemoglobin.
• White blood cells: Fight infections.

Blood Clotting

• Platelets form a plug.
• Fibrin cross-links to form a clot.

Immune System

• Protects against pathogens.
• Defenses: External barriers, inflammatory response, complement system, white blood cells, lymphatic system.

External Barriers

• Skin, hairs/cilia, mucous membranes, gastric juice.

Inflammatory Response

• Chemicals (histamine) trigger response.
• Blood vessels weaken, swelling, phagocytes destroy bacteria.

Complement System

• Proteins form a hole in bacterial cell, causing it to burst.

White Blood Cells

• Innate cells (pre-made) and lymphocytes (produced after contact).
• Phagocytic cells engulf invaders.
• T cells attack abnormal cells.

Lymphatic System

• Network with lymph nodes and vessels.
• Lymph nodes: Lymphocytes attack microbes.

Immune Defenses

• Innate: immediate, generalized.
• Adaptive: slower, invader-specific.

Recognizing Invaders

• Antigen: Molecule that elicits immune response.
• Antibodies: Tag antigens.
• B cells activated: antibodies (antigen tagging proteins) produced

Memory Cells

• Instigate a secondary immune response that neutralizes the invader.

Vaccination

• Exposes immune system to an antigen, stimulates memory cells.

Immune System Issues

• Allergies, autoimmune diseases, organ rejection.
• Not strong enough: Immunodeficiency diseases (e.g., AIDS).

Endocrine System

• Regulates body via hormones.
• Hormones: Chemical signals transported by bloodstream.

Endocrine System Players

• Hypothalamus (control center), pituitary, parathyroid glands, thyroid gland, pancreas, adrenal glands, testes/ovaries.

How Hormones Work

• Target cells have receptors for specific hormones.
• Types: water-soluble & fat-soluble.

Insulin

• Regulates glucose levels.

Diabetes Mellitus

• Body fails to produce enough insulin (type 1) or cells don’t respond to it (type 2).

Urinary System

• Rids body of nitrogen-containing wastes.
• Osmoregulation: Control of water and ions.

Urinary System Players

• Kidneys, renal artery/vein, urinary bladder, ureter, urethra.

The Kidney

• Filters blood.
• Blood enters via renal artery, filtered in nephrons, leaves via renal vein.
• Urine exits via ureter, collects in bladder.

Urine Composition

• Mostly water, urea, ions.

Dialysis

• Machine filters blood, mimics kidney.

Reproductive Systems

• Both males and females produce, store, and deliver gametes.

Male Anatomy

• Testis (gonad), penis, scrotum, vas deferens, epididymis, prostate gland, urethra

Sperm Formation

• Diploid cells divide via meiosis to produce haploid sperm cells (spermatogenesis)

Female Anatomy

• Ovary (gonad), uterus, oviduct, cervix, vagina, vulva.

Egg Formation

• A mature haploid egg (ovum) develops (oogenesis).

Female Reproductive Cycle

• Menstrual cycle (~28 days).
• Ovulation (release of egg) around day 14.

Embryonic Development

• Fertilization → Zygote → Embryo → Fetus.
• First trimester (organ formation), second (growth), third (preparing for birth).
• Pregnancy ~266 days.

Reproductive Health Issues

• Contraception, infertility, STDs.

Contraception

• Deliberate prevention of pregnancy.
• Methods: hormonal birth control, diaphragm and tubal ligation, condom and vasectomy

Infertility

• Inability to conceive after one year.

STDs

• Spread by unprotected sex.
• Viral STDs last a lifetime.

Nervous System

• Communication and coordination network.
• Consists of brain, spinal cord, and nerves.

Nervous System Divisions

• Central nervous system (CNS): Brain and spinal cord.
• Peripheral nervous system (PNS): Nerves.

CNS Functions

• Receives signals → signal integration → response formulation → transmits signals.

CNS Response Types

• Somatic (motor output) and autonomic (heart rate, breathing, etc.).

CNS Key Components

• Brain (integration, control), spinal cord (communication, reflexes).

Brain Areas

• Cerebrum, hypothalamus, cerebellum, brainstem, thalamus.

Nervous System Issues

• Meningitis, concussion, depression, Alzheimer’s disease, paralysis.

Neurons

• Nerve cells that carry electrical signals.
• Axon: Long extension from cell body.
• Synapse: gap at the end of a neuron
• Neurotransmitters: communicate signals via chemical neurotransmitters

Senses

• Receptors detect stimuli and convert to electrical signals.
• Smell (chemicals), photoreceptors (light).

Sensory Receptors

• Pain, thermoreceptors (heat/cold), mechanoreceptors (touch, pressure), electromagnetic (light), chemoreceptors (chemicals).

Signal Transduction

• Converts stimulus to electrical signal.

The Eye

• Focuses light on photoreceptor cells in retina.

Hearing

• Hair cells in inner ear bend and transmit signals.

Taste and Smell

• Chemicals bind to receptors, send signals.

Skeletal System

• Supports body, protects organs.
• Endoskeleton.

Axial Skeleton

• Skull, vertebrae, rib cage

Appendicular Skeleton

• Girdles and bones of the appendages

Bone Composition

• Living tissue that can regenerate.

Joints

• Ligaments hold bones together.
• Types: ball and socket, pivot, hinge, saddle.

Skeletal System Issues

• Fractures, arthritis (inflammation), osteoporosis (low bone density).

Muscular System

• Skeletal muscles anchored to bones by tendons.

Muscle Structure

• Bundles of muscle fibers.
• Sarcomere: functional unit of contraction in muscle fiber

Muscle Contraction

• Sarcomeres shorten, producing movement.
• Muscles act in antagonist pairs (e.g., biceps & triceps).

Botox

• Paralyzes muscles by blocking nerve signals.