Anatomy & Physiology: Cell Structure, Tissue Types, and Integumentary System Study Guide

Cell Structure and Function

Cellular Components

The cell is the basic unit of life, composed of various organelles that perform specialized functions necessary for survival and homeostasis.

• Nucleus: Contains genetic material (DNA) and controls cellular activities.

• Mitochondria: Site of ATP production through cellular respiration.

• Ribosomes: Responsible for protein synthesis; can be free or attached to the endoplasmic reticulum.

• Endoplasmic Reticulum (ER): Rough ER synthesizes proteins; smooth ER synthesizes lipids and detoxifies chemicals.

• Golgi Apparatus: Modifies, sorts, and packages proteins and lipids for secretion or use within the cell.

• Lysosomes: Contain digestive enzymes for breaking down waste materials and cellular debris.

• Peroxisomes: Involved in detoxification of harmful substances, such as hydrogen peroxide.

Example: During the S phase of the cell cycle, DNA replication occurs in the nucleus.

Cell Membrane Structure and Function

The plasma membrane is a selectively permeable barrier composed primarily of a phospholipid bilayer with embedded proteins.

• Phospholipid Bilayer: Provides fluidity and flexibility; hydrophilic heads face outward, hydrophobic tails face inward.

• Integral Proteins: Span the membrane and are involved in transport and cell signaling.

• Peripheral Proteins: Attached to the surface of the membrane and assist in cell communication.

• Cholesterol: Stabilizes membrane fluidity.

Equation:

$\text{Fluid Mosaic Model:} \quad \text{Membrane} = \text{Phospholipids} + \text{Proteins} + \text{Cholesterol}$

Cell Division

Cell division is essential for growth, repair, and reproduction. The two main types are mitosis and meiosis.

• Mitosis: Produces two genetically identical daughter cells; consists of prophase, metaphase, anaphase, and telophase.

• Meiosis: Produces gametes with half the number of chromosomes.

• Cytokinesis: Division of the cytoplasm following mitosis or meiosis.

Example: During mitosis, chromosomes are separated into two nuclei.

Tissue Types

Epithelial Tissue

Epithelial tissue covers body surfaces, lines cavities, and forms glands. It is classified by cell shape and number of layers.

• Simple Epithelium: Single layer of cells; functions in absorption, secretion, and filtration.

• Stratified Epithelium: Multiple layers; provides protection from abrasion.

• Squamous, Cuboidal, Columnar: Refers to cell shape.

Example: Stratified squamous epithelium protects the skin from abrasion.

Connective Tissue

Connective tissue supports, binds, and protects organs. It is characterized by cells embedded in an extracellular matrix.

• Loose Connective Tissue: Provides support and elasticity.

• Dense Connective Tissue: Provides strength; found in tendons and ligaments.

• Cartilage: Provides flexible support.

• Bone: Provides rigid support and protection.

• Blood: Transports nutrients, gases, and wastes.

Example: Dense regular connective tissue forms tendons, which connect muscle to bone.

Muscle Tissue

Muscle tissue is specialized for contraction and movement.

• Skeletal Muscle: Voluntary movement; striated appearance.

• Cardiac Muscle: Involuntary; found in the heart; striated and branched.

• Smooth Muscle: Involuntary; found in walls of hollow organs; non-striated.

Example: Smooth muscle cells are connected to each other by intercalated discs in cardiac tissue.

Nervous Tissue

Nervous tissue is responsible for transmitting electrical impulses throughout the body.

• Neurons: Conduct nerve impulses.

• Neuroglia: Support and protect neurons.

Example: The brain and spinal cord are composed primarily of nervous tissue.

Integumentary System

Structure of the Skin

The skin is the largest organ of the body and consists of two main layers: the epidermis and the dermis.

• Epidermis: Outermost layer; composed of stratified squamous epithelium.

• Dermis: Deeper layer; contains connective tissue, blood vessels, nerves, and glands.

• Subcutaneous Layer (Hypodermis): Not part of the skin; consists of adipose tissue.

Example: The reticular layer of the dermis consists of dense irregular connective tissue.

Functions of the Skin

The skin serves as a protective barrier and performs several vital functions.

• Protection: Against mechanical injury, pathogens, and UV radiation.

• Regulation: Temperature regulation through sweat and blood flow.

• Sensation: Contains sensory receptors for touch, pain, and temperature.

• Excretion: Removes waste products through sweat.

• Synthesis: Produces vitamin D when exposed to sunlight.

Example: Melanocytes in the epidermis produce melanin, which protects against UV radiation.

Hair and Nails

Hair and nails are accessory structures of the skin, composed primarily of keratin.

• Hair: Provides protection and sensory input; consists of the shaft, root, and follicle.

• Nails: Protect the tips of fingers and toes; composed of hard keratin.

Example: The stratum basale is the layer of the epidermis where hair growth begins.

Body Cavities and Membranes

Major Body Cavities

The body is divided into several cavities that house organs and provide protection.

• Cranial Cavity: Contains the brain.

• Thoracic Cavity: Contains the heart and lungs.

• Abdominopelvic Cavity: Contains digestive, urinary, and reproductive organs.

• Ventral Cavity: Includes thoracic and abdominopelvic cavities.

• Dorsal Cavity: Includes cranial and spinal cavities.

Example: The serous membranes line the ventral body cavities and cover the organs within them.

Serous Membranes

Serous membranes are thin tissues that line body cavities and secrete lubricating fluid.

• Pleura: Surrounds the lungs.

• Pericardium: Surrounds the heart.

• Peritoneum: Surrounds abdominal organs.

Example: The pleural cavity is the space between the layers of the pleura surrounding the lungs.

Summary Table: Major Tissue Types

Tissue Type	Main Function	Location Example
Epithelial	Protection, absorption, secretion	Skin, lining of GI tract
Connective	Support, binding, protection	Tendons, ligaments, bone
Muscle	Movement	Skeletal muscles, heart, walls of organs
Nervous	Communication, control	Brain, spinal cord, nerves

Additional info:

• Some questions reference the cell cycle phases (G1, S, G2, M), which are important for understanding cell division and growth.

• Questions about the skin reference layers such as the stratum basale and stratum corneum, which are key to understanding epidermal structure.

• Questions on tissue types and their functions provide foundational knowledge for later study of organ systems.