Diversity of the cell and their functions

Question 1

Explain how to prepare a tissue for looking at under a microscope

Answer 1

1. Use a fixative
2. Thinly slice the tissue to allow for light penetration
3. Apply support material by dehydrating tissue, placing into solvent then into hot wax until fully penetrated
4. Thin sections of tissue cut on a microtome, put onto slide, washed then re-hydrated
5. This produces a change termed artifacts
6. Stain tissue (usually with Haemotoxylin and Eosin)

Question 2

Name the 4 basic tissue types

Answer 2

1. Endothelium
2. Connective tissue
3. Muscle tissue
4. Nervous tissue

Question 3

Describe 4 features of endothelia

Answer 3

1. Has a strong adhesion thus forming sheets of cells with minimum intercellular space so good for covering surfaces and lining organs
2. They have a basal lamina to which the cells are attached to
3. They are all non-vascular meaning nutrients must diffuse across the basal lamina
4. The cells are usually polarised

Question 4

Name 5 functions of epithelium

Answer 4

1. Chemical barrier
2. Secretion
3. Absorption
4. Mechanical barrier (e.g skin)
5. Locomotion (by cilia)

Question 5

Describe the classifications of covering epithelia

Answer 5

1. cell shape - squamos, cuboidal, columnar
2. Number of layers - simple (1), stratisfied (>1), pseodostratisfied (all cells in contact with basal lamina but appear stratisfied)
3. Cell surface - prominent microvili (brush border), cilia or keratinized
4. Presence of specialized cell types - goblet cells

Question 6

What is glandular epithelia?

Answer 6

Glandular epithelia produces secretory products (e.g sweat, milk, oil, hormones etc)

Question 7

Name the 2 epithelium glands and explain the difference between them

Answer 7

1. Endocrine glands which secrete a product towards the basal end of the cell then distributes it by the vascular system throughout the body. These are termed “ductless”
2. Exocrine glands which secrete a product towards the apical end of the cell into either a duct, lumen of an internal space or onto the body surface. These are termed “ducted”

Question 8

Name the 3 types of connective tissue and give a couple examples for each

Answer 8

1. Soft connective tissue - tendons and ligaments
2. Hard connective tissue - Bone and cartilage
3. Blood and lymph - considered as a special form of connective tissue

Question 9

What determines the type of connective tissue?

Answer 9

The type and relative amount of the extracellular matrix and cells

Question 10

What is the extracellular matrix composed of?

Answer 10

It surrounds the connective tissue and is composed of fibres such as collagen, a ground substance and tissue fluid

Question 11

Name the different types of cells found in connective tissue and explain what each of them are

Answer 11

1. Fibroblasts - widely distributed cells that produce and maintain the extracellular matrix
2. Adipose cells - Fat cells found scattered in some connective tissue but mainly fat tissue
3. Osteocytes - Cells of the bone
4. Chondrocytes - Cells of cartilage

Question 12

Explain the 3 classifications of soft connective tissue

Answer 12

1. Loose - Loose packed fibres and cells are relatively plentiful
2. Dense regular - when fibres are packed but aligned (e.g tendon)
3. Dense irregular - when fibres are packed but run in many directions (e.g dermis of the skin)

Question 13

Name some properties of hard connective tissue

Answer 13

1. Strong, flexible and semi-rigid tissue

2. Cartilage is avascular (lack of blood vessels) and receives nutrients from adjacent tissues by diffusion

Question 14

How many types of cartilage are there and what are they?

Answer 14

There are three types:

1. Hyaline (most common) - in the tracheal rings, costal cartilage for example
2. Elastic
3. Fibrocartilage

Question 15

How many types of bone can be recognised with the naked eye and explain the structure of the bone?

Answer 15

There are two types of bone - an outer layer of dense CORTICAL bone which makes up the diaphysis (shaft - midsection of a long bone) and CANCELLOUS bone occupies the ends of the bone (epiphyses) which is like a meshwork

Question 16

What is the function of muscle cells and how do they work?

Answer 16

Muscle cells are highly specialized cells to produce force by the movement of actin fibres over myosin fibres with the aid of accessory proteins

Question 17

Describe the major types of muscle tissue

Answer 17

There are 3 major types of muscle tissue:

1. Smooth muscle - also called involuntary/visceral, simplest muscle type, no visible striations
2. Skeletal muscle - Voluntary/striated, muscle of the body that responds to conscious control, multinucleated
3. Cardiac muscle - Forms major part of walls of heart chambers, has striations, form a complex network, have intercalated discs (end to end attachments between cells)

Question 18

Explain the structure of nervous tissue

Answer 18

Nervous tissue consists of neurons and support cells (glia). It is normally surrounded by a connective tissue “coat” however the brain lacks this coat

Question 19

Neuron are diverse but they fall into 3 main types. Name these and explain a bit about them.

Answer 19

1. Multipolar - most common, many dendrites and one axon
2. Bipolar - one dendrite and one axon
3. Pseudounipolar - short process which gives rise to axon in both directions

Question 20

What are axons and dendrites?

Answer 20

An axon is a portion of a nerve cell (neuron) that carries nerve impulses away from the cell body. A neuron typically has one axon that connects it with other neurons or with muscle or gland cells.
Dendrites are projections of a neuron that receive signals from other neurons

Question 21

What are the principle glia of the CNS and what do they do?

Answer 21

Astrocytes - provide support, ion transport and induce blood brain barrier
Oligodenrocytes - produce myelin in the brain and the spinal cord
Microglia - Provide immune surveillance

Question 22

What is the principle glia of the PNS and what does it do?

Answer 22

Schwann cells - produce myelin and support axons