Orientation to the Body

Definitions: Anatomy and Physiology

• Anatomy: The study of the structure of body parts and their relationships to one another.

• Physiology: The study of the function of the body’s structural machinery—how the body parts work and carry out their life-sustaining activities.

Characteristics of Living Things

• Organization

• Metabolism

• Responsiveness

• Growth

• Development

• Reproduction

• Homeostasis

Levels of Organization in the Body

• Chemical (atoms & molecules)

• Cellular

• Tissue

• Organ

• Organ System

• Organism

Anatomical Position and Directional Terms

• Anatomical Position: Body erect, feet slightly apart, palms facing forward, thumbs pointing away from the body.

• Importance: Provides a standard reference for describing locations and directions on the body.

• Directional Terms: Superior, Inferior, Anterior (Ventral), Posterior (Dorsal), Medial, Lateral, Proximal, Distal, Superficial, Deep.

Body Planes and Sections

• Sagittal Plane: Divides the body into right and left parts.

• Frontal (Coronal) Plane: Divides the body into anterior and posterior parts.

• Transverse (Horizontal) Plane: Divides the body into superior and inferior parts.

Regional Terms and Surface Anatomy

• Examples: Axillary (armpit), Frontal (forehead), Brachial (arm), Femoral (thigh), etc.

Homeostasis

• Definition: The maintenance of a stable internal environment despite changes in the external environment.

• Example: Regulation of body temperature.

• Homeostatic Control Mechanism Steps:

  1. Stimulus

  2. Receptor

  3. Input (Afferent Pathway)

  4. Control Center

  5. Output (Efferent Pathway)

  6. Effector

  7. Response

• Negative Feedback Example: Blood glucose regulation by insulin and glucagon.

Major Body Systems (Overview)

• Integumentary System: Protection, temperature regulation, sensation, vitamin D synthesis.

• Skeletal System: Support, protection, movement, mineral storage, blood cell formation.

• Muscular System: Movement, posture, heat production.

• Nervous System: Fast-acting control system, responds to internal and external changes.

Histology

Introduction to Histology and Tissues

• Histology: The study of tissues.

• Tissue: A group of similar cells that perform a common function.

The Four Basic Tissue Types

Extracellular Matrix (ECM)

• ECM: Non-cellular material found between cells in connective tissue; consists of fibers and ground substance.

• Fibers: Collagen (strength), elastic (flexibility), reticular (support).

• Ground Substance: Gel-like material that fills space between cells and fibers.

Naming Epithelial Tissues

• Based on number of layers (simple, stratified) and cell shape (squamous, cuboidal, columnar).

• Example: Simple squamous epithelium—single layer of flat cells.

Intercellular Junctions

• Tight Junctions: Prevent leakage between cells.

• Desmosomes: Anchor cells together.

• Gap Junctions: Allow communication between cells.

Glands

• Exocrine Glands: Secrete products into ducts (e.g., sweat, saliva).

• Endocrine Glands: Secrete hormones into the bloodstream (e.g., thyroid, pituitary).

• Serous Glands: Secrete watery fluids.

• Cytogenic Glands: Release whole cells (e.g., testes, ovaries).

• Mucous Glands: Secrete mucus.

Membranes

• Cutaneous Membrane: Skin; covers the body surface.

• Serous Membrane: Lines body cavities closed to the exterior (e.g., peritoneum, pleura).

• Mucous Membrane: Lines body cavities open to the exterior (e.g., digestive tract).

Cartilage Types

Loose Connective Tissues

• Areolar: All three fiber types; wraps and cushions organs.

• Adipose: Fat storage; insulates and protects organs.

• Reticular: Reticular fibers; supports lymphoid organs.

Muscle Tissue Types

Nervous Tissue

• Neurons: Transmit electrical signals.

• Neuroglia: Support, protect, and nourish neurons.

Integumentary System

Skin as a Membrane

• The skin is classified as a cutaneous membrane.

Functions of the Skin

• Protection (physical, chemical, biological barriers)

• Body temperature regulation

• Sensation

• Metabolic functions (e.g., vitamin D synthesis)

• Blood reservoir

• Excretion

Cells of the Epidermis

• Melanocytes: Produce melanin, which protects against UV radiation.

• Keratinocytes: Produce keratin, a protein that strengthens and waterproofs the skin.

Factors Affecting Skin Color

• Melanin, carotene, hemoglobin, genetics, and environmental factors.

Layers of the Epidermis (from deep to superficial)

1. Stratum basale

2. Stratum spinosum

3. Stratum granulosum

4. Stratum lucidum (only in thick skin)

5. Stratum corneum

Layers of the Dermis

• Papillary Layer: Areolar connective tissue; contains dermal papillae.

• Reticular Layer: Dense irregular connective tissue; provides strength and elasticity.

Subcutaneous Layer (Hypodermis)

• Composed mainly of adipose tissue; anchors skin to underlying structures, insulates, and stores energy.

Arrector Pili Muscles

• Small muscles attached to hair follicles; cause hair to stand up (goosebumps) in response to cold or fear.

Skin in Temperature Regulation

• Sweating, vasodilation, vasoconstriction, insulation by subcutaneous fat.

Skin in Protection Against Pathogens

• Physical barrier, acid mantle, antimicrobial proteins, immune cells in the skin.

Hair

• Functions: Protection, sensation, reduction of heat loss.

• Composition: Dead keratinized cells; shaft, root, follicle.

Sweat Glands

Sebaceous Glands

• Secrete sebum (oil) into hair follicles; lubricate and waterproof skin and hair.

• Located throughout skin except palms and soles; most abundant on face and scalp.

Ceruminous and Mammary Glands

• Ceruminous Glands: Produce earwax; found in external ear canal.

• Mammary Glands: Produce milk; found in breasts.

Homeostatic Imbalance of the Skin (Example: Psoriasis)

• Cause: Autoimmune disorder causing rapid skin cell turnover.

• Affected Parts: Epidermis (especially stratum corneum).

• Symptoms: Red, scaly patches; itching; discomfort.

• Risk Groups: Genetic predisposition; adults more commonly affected.

Burn Classifications

Exam Format (for Reference)

• ~100 points total

• ~80 points: Multiple choice, matching, labeling diagrams, true/false

• ~20 points: 2-4 short answer questions

• One attempt, timed, LockDown Browser and webcam required

Additional info: Some content (e.g., cell anatomy and physiology) is review only and not tested in this unit. The above guide covers all major topics listed in the study guide, with expanded academic context for clarity and completeness.