Integumentary System and Basic Cell Structure

Vocabulary flashcards covering cellular biology, tissue types, the structures of the integumentary system, and age-related changes as presented in the PSW 3 Day 2 lecture.

Cells

The basic functional unit of body structure which require nutrients, water, and oxygen to live.

Nucleus

The control center of the cell that directs activities, is responsible for reproduction, and contains threadlike chromosomes ($DNA$).

Genes

Passed to new cells during reproduction, these determine inherited physical and chemical traits such as height, eye colour, and skin colour.

Mitosis

The process of cell reproduction where a cell duplicates its chromosomes and divides in half to create two identical cells, each with $46$ chromosomes.

Cytoplasm

The fluid-based material outside the nucleus and inside the plasma membrane that supports internal structures and contains organelles like mitochondria and ribosomes.

Cell membrane

The fragile, semi-permeable lipid (fat) outer boundary that encloses the cell and helps it hold its shape.

Epithelial Tissue

Tissue that covers internal and external body surfaces, lacks its own blood supply, and functions in protection, absorption, secretion, and filtration.

Connective Tissue

Tissue found in every part of the body that anchors, connects, and supports other tissues; examples include bone, blood, and adipose tissue.

Muscle Tissue

Tissue responsible for almost all body movement through contraction, classified into skeletal, smooth, and cardiac types.

Nerve Tissue

The major tissue of the nervous system, including the brain and spinal cord, responsible for relaying information throughout the body.

Homeostasis

A stable internal environment maintained by organs working together in organ systems.

Integumentary System

An organ system consisting of the skin, hair, nails, and exocrine glands; "integument" means covering.

Skin

The largest organ in the body, weighing an average of $10\text{ pounds}$ with a surface area of almost $20\text{ square feet}$.

Epidermis

The most superficial outer layer of skin, measuring a tenth of a millimeter thick, which contains no blood vessels and receives nutrients via diffusion from the dermis.

Keratinocytes

Also known as Basal Cells, these make up almost $90\%$ of the epidermis and produce keratin to thicken and waterproof the skin.

Melanocytes

Cells that make up about $8\%$ of the epidermis and produce melanin, the dark pigment that protects against $UV$ rays.

Langerhans Cells

Cells in the epidermis that detect and fight pathogens attempting to enter the body through the skin.

Cyanosis

A bluish discoloration of the lips, ear lobes, and nail beds.

Dermis

The deeper layer of skin made of dense irregular connective tissue that gives the skin strength and elasticity.

Dermal papillae

Finger-like extensions in the papillary layer of the dermis that provide nutrients and oxygen to the epidermis.

Subcutaneous Tissue

Also called hypodermis, this fatty adipose tissue layer stores energy as triglycerides and helps insulate the body.

Eccrine Sweat Glands

Glands found in almost every body region that secrete water and sodium chloride to lower body temperature via evaporation.

Apocrine Sweat Glands

Glands located in axillary and pubic regions that become active at puberty and produce body odor.

Sebaceous Glands

Exocrine glands in the dermis that produce sebum, an oily secretion that waterproofs and lubricates the skin and hair.

Enamel

The hardest substance in the body, which forms the hard outer layer of the tooth's crown.

Elastosis

The reduction of skin strength and elasticity due to connective tissue changes, often resulting in a leathery appearance from sun exposure.

Free Nerve Ending (FNE)

The most common type of unspecialized afferent nerve ending in the skin that detects temperature, pain, and mechanical stimuli.