Anatomy and Physiology: Body Structure, Function, and Tissue Types

Anatomy

The branch of biology that studies the structure, shape, and organization of body parts and their relationships to each other.

Physiology

The branch of biology that studies how body parts function and carry out life-sustaining processes.

Cell

The smallest structural and functional unit of life; carries out all life processes.

Tissue

A group of similar cells and their extracellular material that work together to perform a specific function.

Organ

A structure composed of two or more tissue types that work together to perform specific functions.

Organ system

A group of organs that cooperate to accomplish a common purpose in the body.

Homeostasis

The ability of the body to maintain a stable internal environment despite external changes.

Negative feedback

A process in which the body reverses a deviation from a set point to maintain homeostasis. Example: regulation of blood pressure.

Positive feedback

A process that amplifies a change from the normal state. Example: childbirth, ovulation, blood clotting.

Stimulus

Any change in the environment that disrupts homeostasis.

Controlled condition

The variable in the body being monitored (e.g., blood glucose, temperature).

Receptor

A structure that detects a change in a controlled condition and sends input to the control center.

Control center

Integrates input from receptors, determines response, and sends output to effectors (usually the brain).

Effector

A structure that brings about a change to alter the controlled condition (e.g., muscles, glands).

Cranial cavity

Contains and protects the brain.

Vertebral cavity

Contains and protects the spinal cord.

Thoracic cavity

Contains lungs (pleural cavities), heart (pericardial cavity), trachea, esophagus, major blood vessels (mediastinum).

Abdominal cavity

Contains stomach, liver, spleen, gallbladder, pancreas, small intestine, most of large intestine.

Pelvic cavity

Contains urinary bladder, reproductive organs, rectum.

Body planes

Imaginary lines dividing the body; include sagittal (right/left), midsagittal (equal halves), frontal (anterior/posterior), transverse (top/bottom), oblique (angled).

Directional terms

Superior (toward head), inferior (toward feet), anterior/ventral (front), posterior/dorsal (back), medial (toward midline), lateral (away from midline), proximal (closer to trunk), distal (farther from trunk), superficial (near surface), deep (away from surface).

Epithelial tissue

Tissue covering body surfaces, lining cavities; functions: protection, absorption, secretion.

Connective tissue

Supports, binds, transports; contains cells scattered in extracellular matrix (examples: bone, cartilage, fat, blood).

Muscle tissue

Produces movement; types: skeletal (voluntary), cardiac, smooth (involuntary).

Nervous tissue

Transmits impulses; found in brain, spinal cord, nerves.

Merocrine gland

Secretes products via vesicles without losing cell material (e.g., sweat glands).

Apocrine gland

Secretes by pinching off top portion of cell (e.g., mammary glands).

Holocrine gland

Secretes by entire cell rupturing (e.g., sebaceous/oil glands).

CAMs

Proteins on cell surface for adhesion and communication; types: cadherins, integrins, selectins, IgCAMs, desmosomes, hemidesmosomes, gap junctions.

Layers of skin

Epidermis (outer), Dermis (middle), Hypodermis (subcutaneous).

Epidermis layers

Basale (deepest, stem cells), Spinosum, Granulosum, Lucidum (thick skin only), Corneum (superficial, dead keratinocytes).

Dermis layers

Papillary (fingerprints, loose connective tissue), Reticular (dense irregular connective tissue, strength).

Melanin

Brown/black pigment; UV protection.

Carotene

Yellow/orange pigment; dietary; converted to vitamin A.

Hemoglobin

Red pigment in blood; gives pink skin tone.

Bilirubin

Yellow pigment; from hemoglobin breakdown; causes jaundice if high.

Pheomelanin

Red/yellow melanin pigment; lighter skin/hair.

Eumelanin

Brown/black melanin; darker skin/hair.

Keratinocyte

Produces keratin; major epidermal cell.

Melanocyte

Produces melanin; found in basal layer.

Langerhans cell

Immune defense; antigen-presenting.

Merkel cell

Touch receptor.

Sebaceous gland

Produces sebum; usually near hair follicle.

Apocrine sweat gland

Thick sweat; armpits, groin; produces odor with bacteria.

Long bone parts

Diaphysis (shaft), Epiphysis (ends), Metaphysis (growth plate), Articular cartilage (joint surface), Medullary cavity (marrow), Periosteum (outer covering), Endosteum (inner lining).

Bone cells

Osteoblasts (build), Osteocytes (maintain), Osteoclasts (break down).

Hormones in bone

PTH (raises calcium), Calcitriol (vitamin D; increases calcium absorption), Calcitonin (lowers calcium).

Minerals for bone

Calcium, phosphate, magnesium, fluoride, manganese.

Epiphyseal plate zones

Resting cartilage, Proliferating cartilage, Hypertrophic cartilage, Calcified cartilage, Ossification.

Fracture repair steps

Hematoma → Fibrocartilaginous callus → Bony callus → Remodeling.

Ossification

Intramembranous (flat bones), Endochondral (long bones).