Soft tissue

Question 1

What are the four types of soft tissue

Answer 1

> Connective tissue - fills internal spaces
Epithelial tissue - Covers exposed surfaces
Muscle Tissue - Contracts
Nervous tissue - Transmits messages via electrical stimulation

Question 2

What are the two main types of epithelial tissue

Answer 2

> 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

Question 3

What are the common features of epithelial tissue

Answer 3

> 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

Question 4

What are the main functions of epithelial tissue

Answer 4

1. Physical protection
   - vs abrasion/dehydration/destruction via chemical/biological agents
2. Control Permeability
   - All substances exiting/entering body cross epithelium
   - Varies depending on surface
3. Sensation
   - Large Nerve supply - constant info on internal/external environments
4. Specialised secretions
   - via glands onto surface of epithelia or into interstitial fluid to diffuse into blood

Question 5

How is epithelial tissue classified

Answer 5

> 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

Question 6

What are the two types of glands

Answer 6

> 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)

Question 7

Describe connective tissue

Answer 7

• Occurs throughout body
• Not exposed to external environment
• Connects epithelial tissue to rest of body
• Majority is highly vascular
• Fills internal spaces

Question 8

How is connective tissue classified?

Answer 8

> Connective tissue proper
Fluid CT
Supporting CT

Question 9

What makes up CT proper ?

Answer 9

1. 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
2. Dense CT = fibrous
   a) Regular - collagen is in parallel lines
   b) Irregular - interwoven fibres to withstand multidirectional stresses

Question 10

What makes up fluid CT?

Answer 10

> Blood
Lymph
- transports cells and materials around the body

Question 11

What makes up Supporting CT?

Answer 11

> Bone 
- Support
- Allows movement
- Protects organs
- Mineral deposits (mainly calcium)
> Cartilage 
- In joints
- Protect bone by reducing friction
- Densely packed collagen

Question 12

What are the functions of connective tissue?

Answer 12

> 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)

Question 13

What are the main features of cartilage

Answer 13

• 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)

Question 14

What are the main types of cartilage and where are they found?

Answer 14

1. Hyaline Cartilage
   - closely packed collagen in matrix = tough but flexible
   - found in most joints/respiratory tract/nasal cartilage
2. Elastic cartilage
   - Numerous elastic fibres = resilient but flexible - will return to shape
   - found in external flap of ear/ epiglottis/ larynx
3. Fibrocartilage
   - Densely interwoven collagen + ground substance
   - Durable + tough to resist compression/absorb shock
   - Limits movement
   - found between vertebrae/pubic bones/menisci

Question 15

Describe membranes and name the main types

Answer 15

- Membranes = when epithelial tissue and connective tissue are combined ie epithelium supported by CT
Four types
1. Mucous 
2. Serous
3. Synovial
4. Cutaneous

Question 16

Describe Mucous membranes & where they would be found

Answer 16

• 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

Question 17

Describe Serous Membranes & where they would be found

Answer 17

• 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)

Question 18

Describe Synovial membranes and where they are found

Answer 18

• 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

Question 19

Describe cutaneous membranes

Answer 19

> 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

Question 20

Functions of Cutaneous Membranes

Answer 20

> 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