Soft tissue Flashcards
What are the four types of soft tissue
> Connective tissue - fills internal spaces
Epithelial tissue - Covers exposed surfaces
Muscle Tissue - Contracts
Nervous tissue - Transmits messages via electrical stimulation
What are the two main types of epithelial tissue
> Epithelia - cover internal/external surfaces
- act as barrier to external environment
e.g skin/digestive tract/urinary tract
Glands - produce fluid secretions
- attached to/ derived from epithelia
What are the common features of epithelial tissue
> Cells = bound closely together
Exposed surface
Avascular - obtain nutrients via diffusion/absorption
Cells are continuously regenerating/being replaced
Structure
- Cilia - beat in co-ordinated fashion to move molecules along e.g mucus in lungs
- Microvilli increase SA for absorption/secretion
- Basal surface - attachment to other cells
What are the main functions of epithelial tissue
- Physical protection
- vs abrasion/dehydration/destruction via chemical/biological agents - Control Permeability
- All substances exiting/entering body cross epithelium
- Varies depending on surface - Sensation
- Large Nerve supply - constant info on internal/external environments - Specialised secretions
- via glands onto surface of epithelia or into interstitial fluid to diffuse into blood
How is epithelial tissue classified
> Number of layers
- Simple = single cell layer for high absorption/secretion
- Stratified = multiple layers for protection vs damage
Cell Shape
- Squamous = flat
- Cuboid = squarish
- Columnar = rectangular
What are the two types of glands
> Exocrine
- secrete products directly onto epithelial surface via ducts (e.g sweat/tears/salivary/digestive enzymes)
Endocrine
- Secrete hormones into cellular spaces to diffuse into blood - regulate/co-ordinates activities of tissues/organs/systems (e.g pituitary/thymus/thyroid glands)
Describe connective tissue
- Occurs throughout body
- Not exposed to external environment
- Connects epithelial tissue to rest of body
- Majority is highly vascular
- Fills internal spaces
How is connective tissue classified?
> Connective tissue proper
Fluid CT
Supporting CT
What makes up CT proper ?
- Loose CT (areolar) = loosely packed collagen + elastin fibres (elastic properties) - surrounds organs
- also encompasses Adipose tissue = higher proportion of fat cells to provide padding/insulation/energy storage - Dense CT = fibrous
a) Regular - collagen is in parallel lines
b) Irregular - interwoven fibres to withstand multidirectional stresses
What makes up fluid CT?
> Blood
Lymph
- transports cells and materials around the body
What makes up Supporting CT?
> Bone - Support - Allows movement - Protects organs - Mineral deposits (mainly calcium) > Cartilage - In joints - Protect bone by reducing friction - Densely packed collagen
What are the functions of connective tissue?
> Provide structural framework for body (Bone + Loose CT)
Transport fluids + dissolved material (Fluid CT)
Protect organs (Bone + Loose CT)
Supports/Surrounds/Connects other tissue (Loose CT)
Energy storage (Loose CT - adipose)
Defence from invading micro-organisms (Fluid CT & CT proper via leukocyte storage)
What are the main features of cartilage
- Closely packed collagen fibres in a firm matrix gel
- Chondrocytes (produce + maintain the matrix & stop blood vessel growth)
- Proteoglycans - regulate matrix makeup e.g water levels
- Avascular (absorbs nutrients via matrix and doesn’t heal well)
What are the main types of cartilage and where are they found?
- Hyaline Cartilage
- closely packed collagen in matrix = tough but flexible
- found in most joints/respiratory tract/nasal cartilage - Elastic cartilage
- Numerous elastic fibres = resilient but flexible - will return to shape
- found in external flap of ear/ epiglottis/ larynx - Fibrocartilage
- Densely interwoven collagen + ground substance
- Durable + tough to resist compression/absorb shock
- Limits movement
- found between vertebrae/pubic bones/menisci
Describe membranes and name the main types
- Membranes = when epithelial tissue and connective tissue are combined ie epithelium supported by CT Four types 1. Mucous 2. Serous 3. Synovial 4. Cutaneous
Describe Mucous membranes & where they would be found
- Line passageways that open to the exterior
- Epithelial surface is kept moist by mucus or exposure to fluid to reduce friction & facilitate absorption
- Thin layer of epithelial cells often simple classification
- found in digestive/respiratory/urinary/reproductive tracts
Describe Serous Membranes & where they would be found
- Line sealed, internal subdivisions of body cavities
- Not open to exterior
- Very thin and transparent
- Firmly attached to body wall and organs they cover
- Minimise friction via serous fluid (transudate) production
- Found in pleura (lungs)/ Pericardium (heart)/ Peritoneum (abdomen)
Describe Synovial membranes and where they are found
- Forms synovial capsule around joint cavity (beneath joint capsule = loose connective tissue)
- Atypical epithelium - Made up of connective tissue with layer of macrophages and fibroblasts that regulate synovial fluid
- Synovial fluid nourishes and lubricates hyaline cartilage of joint
- Movement of joint stimulates formation and circulation of synovial fluid
Describe cutaneous membranes
> 2 layers:
- Epidermis: epithelial outer layer
- Dermis = connective tissue - collagen + elastin
2 layers of dermis
a) Loose Ct
b) Dense irregular CT
below the dermis = subcutaneous layer of loose CT
Accessory structures within membrane such as hair follicles/nails/exocrine glands
General facts
- cells last ~ 2 weeks (15-30 days to move to outer layer)
- Hold water via osmosis
- Colour change may indicate pathology
Functions of Cutaneous Membranes
> Protection of underlying tissue
Excretion - salts/water/waste
Maintain temperature - insulation/evaporative cooling
Melanin production - UV protection
Keratin production - repels water/ abrasion protection
Vitamin D3 synthesis - metabolises calcium
Storage of lipids
Sensation
Co-ordination of immune response to pathogens/cancers in skin