Anatomy & Physiology Study Guide: Introduction, Histology, Integument, and Bone Structure

INTRODUCTION – Chapter 1

Anatomy

Anatomy is the study of the structure of the human body and its parts. It focuses on the physical organization, relationships, and locations of organs and tissues.

• Gross anatomy: Study of structures visible to the naked eye.

• Microscopic anatomy: Study of structures requiring magnification, such as cells and tissues.

Physiology

Physiology is the study of the function of body parts and how they work together to sustain life.

• Examines processes such as muscle contraction, nerve signaling, and hormone secretion.

• Focuses on mechanisms that maintain homeostasis.

Homeostasis

Homeostasis refers to the body's ability to maintain a stable internal environment despite external changes.

• Examples: Regulation of body temperature, blood glucose levels, and pH balance.

• Involves feedback mechanisms (negative and positive feedback).

HISTOLOGY – Chapter 4

Categories of Tissues

Histology is the study of tissues. The four main categories are:

• Epithelial tissue

• Connective tissue

• Muscle tissue

• Nervous tissue

Cellular Connections

• Gap junctions: Allow direct communication between adjacent cells via channels.

• Tight junctions: Prevent leakage of substances between cells, maintaining tissue integrity.

• Desmosomes: Provide strong adhesion between cells, especially in tissues subject to mechanical stress.

Glandular Secretions

• Merocrine secretion: Secretions released via exocytosis (e.g., sweat glands).

• Apocrine secretion: Secretions released with part of the cell membrane (e.g., mammary glands).

• Holocrine secretion: Entire cell disintegrates to release its contents (e.g., sebaceous glands).

Types of Glands

• Serous glands: Produce watery, enzyme-rich secretions.

• Mucous glands: Produce thick, mucus-rich secretions.

• Mixed glands: Contain both serous and mucous cells.

Fascia

Fascia is connective tissue that supports and surrounds organs.

• Superficial fascia: Located just beneath the skin; contains fat and loose connective tissue.

• Deep fascia: Dense connective tissue that surrounds muscles, bones, nerves, and blood vessels.

• Subserous fascia: Lies between deep fascia and serous membranes lining body cavities.

Tissue Membranes

• Mucous membranes: Line body cavities open to the exterior; secrete mucus for protection and lubrication.

• Serous membranes: Line closed body cavities; secrete serous fluid to reduce friction.

• Synovial membranes: Line joint cavities; secrete synovial fluid for lubrication.

INTEGUMENT – Chapter 5

Functions of Skin

The skin is the largest organ and serves multiple functions:

• Protection against infection, trauma, and desiccation

• Excretion of salt, water, and wastes

• Regulation of body temperature

• Production of melanin and keratin

• Vitamin D synthesis

• Sensory reception

• Energy (fat) storage

• Coordination of immune response

Layers of Skin

• Epidermis: Outermost layer; flexible, water-resistant, tough, and capable of rapid repair.

• Dermis: Dense irregular connective tissue beneath the epidermis; contains collagen fibers, hair follicles, sweat glands, blood vessels, nerves, and sebaceous glands.

• Hypodermis (subcutaneous layer): Not technically part of the skin, but supports and stabilizes it; contains connective tissue and fat.

Factors Influencing Skin Color

• Melanocytes and melanin: Pigment-producing cells; melanin protects against UV radiation.

• Dermal blood supply: Increased blood flow gives skin a reddish hue; decreased flow causes paleness.

• Cyanosis: Bluish discoloration due to low oxygen levels.

• Carotene: Yellow-orange pigment from diet; can influence skin color.

Accessory Structures of Skin

• Hair and hair follicles: Nonliving structures produced in follicles; types include vellus and terminal hair.

• Sebaceous glands: Discharge oily secretion (sebum) into hair follicles or directly onto skin.

• Sweat glands: Two types: apocrine (found in axillary and inguinal regions) and eccrine (merocrine; widely distributed).

• Nails: Protect dorsal surfaces of fingers and toes.

• Sensory receptors: Tactile corpuscles (Meissner's), lamellar corpuscles (Pacinian), root hair plexus.

Repair of Damaged Skin After Injury

Skin repair involves four phases:

• Inflammation Phase

• Migration Phase

• Proliferative Phase

• Scarring Phase

Effects of Aging on Skin

• Decreased activity of basal cells and weakened connection between epidermis and dermis

• Reduced immune response due to fewer dendritic cells

• Decline in vitamin D production

• Reduced glandular secretion and blood supply

• Thinner hair and decreased elasticity

• Slower skin repair

BONES AND BONE STRUCTURE – Chapter 6

Functions of Bone Tissue

• Support of the body: Provides shape and structural support.

• Leverage: Attachment and leverage points for muscles.

• Protection of the body: Protects vital organs (skull, rib cage, vertebrae, pelvis).

• Blood cell production: Occurs in red bone marrow.

• Storage of minerals: Especially calcium and phosphorus.

• Storage of lipids: Fat stored in yellow bone marrow.

Bone Structure

• Regions of a long bone: Epiphysis, diaphysis, metaphysis, medullary cavity.

• Periosteum: Membranous wrapping around all bones; consists of fibrous outer layer and inner cellular layer.

• Endosteum: Incomplete cellular layer lining the medullary cavity.

• Articular cartilage: Covers bone surfaces in joints.

Types of Bone Tissue

• Spongy (cancellous) bone: Open network of bony arches; found in epiphyses and inside flat bones.

• Compact bone: Dense and solid; forms the outer layer of bones.

Marrow Cavity

• Red bone marrow: Site of blood cell production.

• Yellow bone marrow: Site of fat storage.