Overview
This text is a comprehensive anatomy and physiology resource, covering the structure and function of the human body, cellular and tissue organization, all major body systems, development, genetics, and aging, with integrated clinical relevance throughout.
The Human Body: Organization & Principles
- The body is organized hierarchically: chemical, cell, tissue, organ, organ system, organism.
- There are 11 major organ systems, each with distinct structures and functions.
- Homeostasis is the maintenance of a stable internal environment; regulated mostly by negative feedback.
- Anatomical terminology uses standard positions, directional terms, and planes for consistent reference.
Cells & Tissues
- Cells are the basic living unit; organelles perform specific functions like energy production (mitochondria) or protein synthesis (ribosomes).
- The cell membrane controls entry/exit of substances; transport includes diffusion, osmosis, active transport, endocytosis, and exocytosis.
- Four tissue types: epithelial (covering and glands), connective (support), muscle (movement), and nervous (communication).
Integumentary, Skeletal, and Muscular Systems
- The skin protects, senses, helps regulate temperature, and synthesizes vitamin D; consists of epidermis/dermis and accessory structures (hair, nails, glands).
- The skeleton provides support, movement, and protection; bones undergo growth, remodeling, and repair.
- Muscles contract to move the body; contraction involves sliding filaments in muscle fibers, requires ATP, and can fatigue.
Nervous and Endocrine Systems
- The nervous system (central and peripheral) processes sensory input, controls effectors, maintains homeostasis, and supports higher mental functions.
- Nerves communicate through electrical impulses and neurotransmitters.
- The endocrine system secretes hormones to regulate body processes; secretion is controlled by negative feedback, hormones act via cell surface or nuclear receptors.
Cardiovascular and Blood
- Blood transports gases, nutrients, hormones, and waste; components are plasma, red and white blood cells, and platelets.
- The heart pumps blood through pulmonary (lungs) and systemic (body) circuits; valves maintain one-way flow.
- Blood vessels (arteries, veins, capillaries) transport blood; blood pressure is regulated by neural and hormonal feedback.
Lymphatic System and Immunity
- Lymphatic vessels return interstitial fluid to blood, absorb fats, and participate in immune defense.
- Innate immunity is non-specific (barriers, phagocytes); adaptive immunity is specific, involving T and B lymphocytes and antibody production.
- Vaccinations and memory cells are the basis for long-term immunity.
Respiratory and Digestive Systems
- The respiratory system supplies oxygen, removes carbon dioxide, regulates pH, and helps produce sound; gas exchange occurs in alveoli.
- The digestive system ingests, digests, absorbs, and eliminates food; includes specialized structures from mouth to anus and accessory organs (liver, pancreas).
Nutrition, Metabolism, and Temperature
- Nutrients provide energy and building blocks; balanced intake of carbohydrates, lipids, proteins, vitamins, and minerals is essential.
- Metabolism is all chemical processes in the body; includes anabolism (building) and catabolism (breaking down).
- Body temperature is regulated by balancing heat production and loss, mainly coordinated by the hypothalamus.
Urinary and Reproductive Systems
- The urinary system filters blood, excretes wastes, regulates fluid, electrolyte, and pH balance.
- Nephrons in the kidneys perform filtration, reabsorption, and secretion to form urine.
- The reproductive systems produce gametes (sperm/oocytes), sex hormones, support fertilization and, in females, gestation/lactation.
Development, Genetics, and Aging
- Prenatal development includes fertilization, cell division, formation of germ layers, organogenesis, and fetal growth.
- Genetics studies inheritance; traits are determined by gene alleles, chromosomes, and inheritance patterns (dominant/recessive, sex-linked, polygenic).
- Aging involves progressive loss of cell/tissue function, decreased repair, and increased susceptibility to disease.
Key Terms & Definitions
- Homeostasis — Maintenance of a constant internal environment.
- Osmosis — Diffusion of water across a membrane.
- Negative Feedback — Process that returns a variable to a set point.
- Enzyme — Protein catalyst in chemical reactions.
- Antibody — Protein produced by B cells in response to antigens.
- Action Potential — Electrical signal along a cell membrane.
- Hormone — Chemical messenger secreted into blood to regulate functions.
- Neuron — Nerve cell conducting electrical impulses.
- Alveolus — Lung air sac where gas exchange occurs.
- Nephron — Functional unit of the kidney that forms urine.
Action Items / Next Steps
- Review chapter summaries and key terms for each system.
- Practice labeling diagrams (body regions, cells, bones, organs).
- Complete end-of-chapter self-test and critical thinking questions.
- Focus study on major feedback mechanisms, key physiological processes, and clinical correlations for exams.