Tissues, Part 2 - Epithelial Tissue: Crash Course A&P #3

epithelial tissue

A body tissue that covers the surfaces of the body, inside and out. Keeps organs IN THEIR PERSONAL SPACE. And not all mixed around inside the body.

Proper Epithelium (primary)

Covers/ protects and lines your outer and inner body

glandular epithelium

forms your glands and secretes hormones and other substances

cranial cavity

contains the brain

Epidermis

Outer layer of skin

Pericadial cavity

contains the heart

vertebral cavity

contains the spinal cord

thoracic cavity

contains heart and lungs

abdominal cavity

Contains stomach, intestines, spleen, and liver, and other organs

pelvic cavity

Contains urinary bladder, reproductive organs, and rectum

invagination

the action or process of being turned inside out or folded back on itself to form a cavity or pouch.

Avascular

ALL EPITHELIUM tissues are these. without a blood supply or blood vessels

connective tissue

EPITHELIUM tissues rely on this for support and for blood/materials they need.

EPITHELIUM SHAPES/LAYERING

Shape of individual cells, numbers of layers they form in.

3 basic shapes of epithelium shapes & functions (SCC)

1.) Squamous cells- flat nuclei/ fast absorption and diffusion, making thin membranes. They are flat which makes O2 to move across to other side. E.g air sacs of your lungs. Cheaper cell compared to the other 2!!! Can be disposable. E.g. cheek cells.

2.) Cuboidal cells- spherical nuclei/ cube shaped body/absorb nutrients/ produce secretions (sweat-found in epidermis layer)

3.) Columnar cells- ellipse nuclei/ look like columns absorb nutrients/ produce secretions. E.g. making of stomach lining . They make and secrete mucus.

3 basic shapes of epithelium layering & functions (SSP)

1.) Simple epithelium- one layer of cell

2.) Stratified epithelium- multiple layers set on top of each other, like bricks.

3.) pseudo stratified- mostly just one layer. Cells with DIFFERENT shapes and sizes (contains ALL the cells)

stratified cuboidal tissue

Layers of cube shaped cells. E.g. linings of the glands that leaks sweat & spit

simple squamous epithelium

single layer of flattened cells e.g. lining of air sacs deep in lungs.

Epithelium cells are polar

1.) Apical side- outer surface/upper side/ exposed to outside part of body or internal cavity it's lining (stomach lining side).

2.) Basal side- inner surface/ attached to basement membrane: thin layer of collagen fibers HOLDS epithelium together AND anchors it to the next tissue (connective tissue-blood vessels. Life support materials).

selective permeable (FAE)

Allows some materials to cross it more easily than others and enables the cell to maintain a unique internal environment. ALSO allows some level of absorption, filtration, and excretion (cuboidal cells) of substances.

E.g. a.) Absorption- osmosis/facilitated diffusion/ tissue lining in small intestines: absorb nutrients through diffusion and active transport (against concentration gradient. ATP powered).

B.) Filtration- uterine waste gets filtered through diff epithelium linings from kidneys

2 types of glandular epithelium-facilitate secretions

1.) Endocrine glands- secrete hormones right into your bloodstream or to nearby cells. E.g sexual activity releases waves of hormones, from Brain —> reproductive organs. Effect, increases blood flow into bloodstream.

2.) exocrine glands- secrete their juices into tubes or ducts that lead to the outside of the body. E.g sweat or spit—-> epidermis. Stomach acid —> stomach lining. They all go into docks where they're surfaced into epithelium surfaces.