Cells, tissues and organs

Question 1

List the 4 tissue types and describe the composition and functions of epithelium and connective tissue

Answer 1

• Epithelium: Covering and lining of the body. Specialised according to location and function. Separated from tissue by basement membrane.
• Connective tissue
• Muscle
• Nerve

Question 2

Describe how cells are adapted to their function by means of membrane specialisations.

Answer 2

Cilia and flagella: Allow movement. Microtubule core.

Villi: Increase SA or ‘waft’. Microfilaments.

Question 3

Explain the structure of the basement membrane and why it is important.

Answer 3

• Sheets of matrix at the interface of the parenchyma and stroma tissue
• Functions: Adhesion, barrier, organisation (growth direction)

Question 4

Give examples of the main support cells and common extracellular matrix proteins in connective tissue.

Answer 4

Fibroblasts: ECM for most tissues, collagen and elastin.
Chrondrocyte: ECM for cartilage, collagen II
Adipocyte: Storage and metabolism of fat
Osteoblast: ECM for bone
- ICM is mainly contributed to by 2 classes of macromolecule: Fibrous proteins (collagen) and polysaccharides (GAGs).

Question 5

Outline how cells are organised into tissues and organs.

Answer 5

• Organs: Composed of some/all of the main tissue types

e. g. epithelium + connective tissue + muscle = Small intestine

Question 6

Describe the general structure and arrangement of the layers in tubular organs.

Answer 6

Epithelium
Basement membrane
Lamina propia (connective tissue)
- Collectively these are known as the mucosa

Question 7

Types of Epithelium

Answer 7

Simple
Stratified
Squamous
Cuboidal
Columnar
Transitional

Question 8

Cell junctions

Answer 8

Desmosomes: Attach cells to each other
Hemidesmosomes: Attach cells to the basement membrane
Tight junctions: Prevent passage of substances between cells
Gap junctions: Allow communication between cells

Question 9

Connective tissue

Answer 9

• Support tissue
• 5% cells, 95 % ECM
• ECM is composed of fibres (elastin and collagen) and a ground substance.
• Fibroblasts secrete ECM for most tissues