WEEK 4 - TISSUES Flashcards
What are tissues?
Group of cells with similar structure and function.
What are the 4 primary types of tissues?
1) Epithelial tissue (epithelium)
2) Connective tissue
3) Muscle tissue
4) Nervous tissue
What does epithelial tissues mean?
- Allows body to interact with both its internal and external environments
- “Epi” = upon
- “thelium” = covering or layer of cellular tissue
What holds a cell together?
- Tight junctions: Fusion of phospholipid layers (upper end) (seals off intercellular space)
- Desmosomes: Patch of hook-like proteins (resists mechanical stress)
- Gap junctions: Channel between cells made of protein
What are epithelial cells?
- Often form sheets
- Lower surface of an epithelium rests on a basement membrane which sits on a top of connective tissue
What are the epithelium characteristics?
- Avascular (without blood vessels)
- Receives its nutrients via diffusion from the vascular connective tissue beneath
What is simple in terms of cell layers?
- One layer
- Diffusion, osmosis, filtration, absorption, secretion
What is stratified in terms of cell layers?
- More than one layer
- Protection from abrasion (friction)
What does squamous mean?
Flattened
What does cuboidal mean?
Cube-shaped
What does columnar mean?
Column-shaped
What is simple squamous?
- Generates membranes
- Line and cover organs
- Lines cardiovascular system (endothelium)
- Lines thoracic and abdominal cavities (serosa)
What is glandular epithelium?
- Gland
- One or more cells that SECRETE a product
What is endocrine gland?
Secretions (hormones) diffuse into blood
What is exocrine gland?
Secretions empty into ducts out to surface Milk, sweat, sebum, wax
What are the characteristics of connective tissue?
- Vascular (with blood vessels)
- Most abundant, variable tissue
- Connects body tissues
- Supports, strengthens, protects, movement, internal transportation, insulates, fuel source (energy)
What is extracellular matrix?
- Connective tissue is composed of extracellular matrix which is a non-living material that separates cells
What is ground substance in terms of extracellular matrix?
- Water, adhesion proteins, polysaccharides
- Can be fluid, gel, rubbery, stone-like
What is protein fibres in terms of extracellular matrix?
- Collagen, elastic, reticular
- Account for the functional properties of the tissue
- Collagen (triple helix) most abundant protein in body
What is mucous membranes (mucosa)?
Lines body openings
What are the different types of connective tissues?
- Fibrous - Dense (fibroblasts). Loose (fibroblasts)
- Adipose (adipocytes)
- Blood, bone, cartilage
What are Dense connective tissues?
- More fibres than ground matrix
- Dominant fiber is Collagen
- Regular, irregular and elastic
- Strong, rope-like structures such as
▪ Tendons — attach muscles to bones (regular)
▪ Ligaments — attach bones to bones (regular)
▪ Dermis — lower layers of skin (irregular)
What are loose connective tissues?
- More ground matrix, less cells and fibres (randomly arranged, spaces for oedema)
- Most widely distributed (packing tissue)
- Position organs, blood vessels, nerves
What is adipose tissue?
- Adipocytes accumulate triglycerides
- 90% subcutaneous (fuel, padding, body shape)
- 10% visceral (produces hormones)
- 5% of cells are macrophages
