Skin and Control Systems Flashcards
What system is skin a part of
The Integumentary system
What is the largest organ of the body
Skin
What do Epithelial cells do
Form boundaries on both internal and external surfaces.
How are epithelial arranged
Arranged in sheets, each sheet has 2 surfaces:
the outer apical surface and the inner basal region
What are stratified epithelia
They have more than one layer of cells where surface is subject to stress. Skin and ducts
What are epithelial membranes
Combinations of a layer of epithelial cells and an underlying layer of connective tissue located on the surface of an organ. There are two types: mucous membranes & serous membranes
What do mucous membranes line
Mouth, gastrointestinal tract, airways
What are microvilli
Projections that extend into the surrounding medium. Increased surface area increases diffusion of molecules.
What are Cilia
Cilia are motile and hair-like. They provide propulsive force, produce movement in single cell organisms & propel overlying material in anchored ciliated epithelia.
What are glands
Structures formed from an invagination of an epithelial surface
What are exocrine glands
Connected to the epithelial surface by a duct. Secretions of glands pass along duct and are effective on the surface of epithelium
Describe endocrine glands
Endocrine glands have lost ducts. Secretions (hormones) released into interstitial fluid and diffuse into blood.
What is the function of connective tissue
To connect, anchor and support other tissues. Contains fibres, ground substance & cells.
How are ground substance produced
By connective tissue cells that synthesis connective tissue fibres
What are collagenous fibres
Made of collagen. Flexible, resist stretching.
What are elastic fibres
Numerous branches, loose network, formed from elastin
What are reticular fibres
Fine and highly branched
What are the connective tissue fibres?
- Collagenous fibres
- Elastic fibres
- Reticular fibres
Name the types of connective tissue
- Loose (Areolar): filler, underlies epithelia
- Dense: in tendons and ligaments
- Adipose
What are the two layers of skin
1) outer epithelial layer: epidermis
2) underlying connective tissue layer: dermis
What is the function of skin
1) controls exchange across surface of body
2) prevents entry of harmful substances, e.g. bacteria
3) prevent excessive loss of water
4) protects internal organs from physical damage
5) regulates body temperature
6) metabolic function
What are the major 4 zones of Epidermis
1) stratum germinativum (deepest)
2) stratum granulosum
3) stratum lucidum
4) stratum corneum
Describe hair
- Epidermal cells invaginate the dermal layer to form hair follicle
- Hair is composed of keratin, synthesised in papilla at base of follicle
What is homeostasis?
Homeostasis is any self-regulating process by which an organism tends to maintain stability while adjusting to conditions that are best for its survival.
