Anatomy Chapter 5: The Study of Tissues

Four basic tissue types

Epithelial, connective, muscular, nervous

Function of epithelial tissue

Covers surfaces, lines organs, forms glands

Function of connective tissue

Supports, protects, and binds tissues

Function of muscular tissue

Specialized for voluntary and involuntary movement

Function of nervous tissue

Transmits information between cells

Defining feature of epithelial tissue

Cells are tightly packed with no extracellular matrix

Arrangement of epithelial cells

Simple (one layer) or stratified (multiple layers)

What epithelial tissue rests on

A basement membrane

What epithelial cells are exposed to

Free surface (internal or external environment)

Is epithelial tissue vascular or avascular?

Avascular

How epithelial tissue gets nutrients

From underlying connective tissues

Special property of epithelial tissue

Highly regenerative

Does epithelial tissue have a nerve supply?

Yes, it is innervated

Functions of epithelia

Protection: Acts as a barrier against pathogens, chemicals, and physical damage (e.g., skin epithelium).

Secretion: Produces substances like mucus, enzymes, hormones, and sweat (e.g., glandular epithelium).

Excretion: Removes waste products (e.g., CO2 in lungs, bile in liver).

Absorption: Absorbs nutrients (e.g., small intestine epithelium).

Filtration: Selectively filters substances from the blood (e.g., kidneys).

Sensation: Contains nerve endings for sensory functions (e.g., skin and digestive tract).

Defining characteristic of simple epithelia

One layer of cells

Function of simple squamous epithelium

Diffusion, filtration, osmosis

Where simple cuboidal epithelium is commonly found

Glands and kidney tubules

Primary function of simple columnar epithelium

Absorption and secretion

What pseudostratified epithelium looks like

Appears layered, but all cells touch the basement membrane

Main function of stratified squamous epithelium

Protection

Difference between keratinized and non-keratinized epithelium

Keratinized has dead cells containing keratin at the surface; non-keratinized does not

Where transitional epithelium is found

Lining the urinary bladder

Primary feature of connective tissue

Abundant extracellular matrix

Role of fibroblasts in connective tissue

They produce the matrix

Collagen fibers

Tough, flexible fibers that resist stretching

Reticular fibers

thin collagen fibers coated with glycoprotein that form a sponge-like framework of support)

Elastic fibers

Fibers made of elastin protein, allowing for stretch and recoil

Ground substance in connective tissue

Gelatinous/rubbery material that fills spaces between fibers and cells

Function of areolar tissue

Binds and supports tissues

Function of reticular tissue

Forms supportive frameworks for lymphatic organs

Function of dense regular connective tissue

Resists stress in one direction

Function of dense irregular connective tissue

Withstands stress in multiple directions

Adipocytes

Cells in adipose tissue that store fat

Two types of fat

White fat and brown fat

Function of white fat

Energy storage, insulation, and cushioning

Primary role of brown fat

Heat generation

Cartilage composed of

Chondroblasts and a flexible, rubbery matrix

Chondrocytes

Mature cartilage cells in lacunae

Why cartilage repairs slowly

It has no direct blood supply

Most common type of cartilage

Hyaline cartilage

Function of elastic cartilage

Provides flexible support

Function of fibrocartilage

Resists compression

Matrix of bone tissue

Hard, calcified, and solid

Osteoblasts

Cells that produce bone matrix

Two types of bone

Spongy bone and compact bone

Function of compact bone

Provides strength and structural support

Plasma

The fluid matrix of blood

Formed elements in blood

Red blood cells, white blood cells, and platelets

Red blood cells

Transport oxygen

Platelets

Clot blood to prevent blood loss

Nervous tissue

Transmitting electrical and chemical signals

Nervous tissue location

Brain, spinal cord, nerves, and ganglia

Neurons

Cells that transmit signals

Neuroglia

Cells that support and nourish neurons

Skeletal muscle

Voluntary movement

Smooth muscle

Involuntary contraction without striations

Cardiac muscle location

In the heart only

Desmosomes

Provide strong cell adhesion, allowing tissues to resist mechanical stress. 

Glands composition

Epithelial tissue and some connective tissue

Merocrine gland secretion

Secretion via exocytosis (sweat glands, tear glands, salivary glands)

Holocrine gland secretion

Secretion through rupture of cells (sebaceous oil glands)

Membranes composition

Epithelial tissue, connective tissue, or both

Largest membrane in the body

The cutaneous membrane (skin)

Mucous membranes

Membranes that line passages open to the external environment

Serous membranes

internal, double-layered membrane that secretes a watery fluid (serous fluid) and lines the outside of organs (visceral layer) and the cavities in which they sit (parietal layer)

Serous fluid function

Reduces friction between layers of serous membranes

Two layers of serous membranes

Visceral layer and parietal layer

Visceral pericardium

Covers the surface of the heart

Pericardial cavity

Filled with serous fluid

Parietal pleura

Lines the walls of the thoracic cavity

Visceral pleura

Covers the surface of the lungs

Pleural cavity

Filled with serous fluid

Parietal peritoneum

Lines the walls of the abdominal cavity

Visceral peritoneum

Covers the surfaces of abdominal organs

Peritoneal cavity

Filled with serous fluid

Main types of glands

Exocrine and endocrine glands

Exocrine glands secretion

Sweat, enzymes, and mucus via ducts

Endocrine glands release

Hormones directly into the bloodstream

Mast cells function

Increase blood flow by releasing chemicals

Blood as connective tissue

Transport nutrients, gases, wastes, and hormones

Macrophages role

Engulf and digest pathogens and debris

Adipose tissue role

Energy storage and insulation

Hyaline cartilage function

Supports and reduces friction in joints. It is glassy and found in the trachea and ends of bones.

Spongy bone function

Provides structural support with spaces for bone marrow

Lamellae in bone tissue

Concentric rings of matrix in compact bone

Osteocytes location

Reside in lacunae within the bone matrix

Cardiac muscle function

Pump blood involuntarily

Skeletal muscle defining feature

Striations and multiple nuclei per cell

Smooth muscle location

In walls of hollow organs and blood vessels

Gap junctions function

Allow for cell-to-cell communication. Water-soluble ions and molecules.

Tight junctions function

Prevent leakage between adjacent cells by sealing them.

apocrine gland

Fat secreting portions of mammary glands.

Desmosomes

Joins the intermediate filaments in one cell to those in a neighbor.

Hemidesmosomes

anchors intermediate filaments in a cell to the basal lamina.

Histology

The study of tissues.

tissue

A group of similar cells and their products that originate from the same region of the embryo and work together to perform a specific function.

three primary germ layers

Ectoderm, Mesoderm, Endoderm.

Ectoderm

Gives rise to the epidermis and nervous system.

Endoderm

Forms mucous membranes of digestive/respiratory tracts and digestive glands.

Mesoderm

Forms mesenchyme, which gives rise to connective tissues (bone, blood, cardiac muscle).