2 - Examining Cells & Tissues

Question 1

What are the 4 classifications of tissue?

Answer 1

1. Epithelial
2. Connective
3. Muscle
4. Nerve

Question 2

What is epithelial tissue?

Answer 2

• Lines all the body surfaces and often surrounds other tissues
• Sometimes in clusters with other tissues (glands)
• At surfaces, always have a basement membrane
• Held together by strong anchoring proteins

Question 3

What do epithelial cells often secrete from their apical surface? How does this benefit the cells?

Answer 3

Secretes sugars from the apical surface - called the glycocalyx

Attracts water to the cells to stop them drying out

Question 4

What are the different types of connective tissue?

Answer 4

• Fibrous (dense) connective tissue
• Loose connective tissue
• Cartilage
• Adipose tissue
• Bone
• Blood

Question 5

What is the main cell type in tendons and ligaments?

Answer 5

Fibroblasts

Question 6

What is the main cell type in cartilage?

Answer 6

Chondrocytes

Question 7

What are the main cell types in bone?

Answer 7

Osteocytes, osteoblasts and osteoclasts

Question 8

What are the main products of cells in connective tissue?

Answer 8

• Fibres (many types)
• Ground substance
• Wax and gel-like materials

Question 9

What are the connective tissue layers of a nerve and where are they found?

Answer 9

Epineurium - surrounds the whole nerve
Perineurium - surrounds nerve fascicles within the epineurium
Endoneurium - inside the nerve fascicles surrounding the neurones

Question 10

What are the 3 types of muscle cell?

Which of these are striated?

Answer 10

• Skeletal (striated)
• Cardiac (striated)
• Smooth (non-striated)

Question 11

What are the major functions of the muscles?

Answer 11

To contract!

• Movement
• Stability of whole body, organs and tissues
• Movement of tissue contents (e.g. peristalsis)

Question 12

What is a minor function of muscle tissue?

Answer 12

To secrete hormones

• Natriuretic factors - produced by the heart to reduce water in the blood via kidneys
• Myostatins - control heart growth

Question 13

What cell has the largest average volume?

Answer 13

The oocyte

Question 14

What is the limit of resolution?

Answer 14

The smallest distance by which two objects can be separated and still be distinguishable as two objects.

Question 15

Compared to a microscope, the naked eye cannot discern objects that are very close together, it is said to have a low ………… …………

Answer 15

Resolving power

Question 16

Put these imaging techniques in order of resolving power (highest to lowest):

• scanning electron microscope
• light microscope
• transmission electron microscope
• naked eye

Answer 16

1. Transmission electron microscope
2. Scanning electron microscope
3. Light microscope
4. Naked eye

Question 17

Which of the electron microscope or the light microscope has the largest field of view?

Answer 17

Light microscope

Question 18

What is the magnification of a light microscope and an electron microscope?

Answer 18

Light - x600

EM - x500,000

Question 19

What is the resolution of a light microscope and electron microscope?

Answer 19

Light - 0.25 μm

EM - 0.25 nm

Question 20

What is the preparation process for electron microscopy?

Answer 20

1. Fix with glutaraldehyde
2. Embed in epoxy resin
3. Stain with osmium tetroxide
4. Cut with microtome (diamond knife)

Question 21

Fixation and preservation of tissue for imaging prevents ……………

Answer 21

Putrefaction (rotting)

Question 22

What is the thickness of tissue needed for light microscopy?

Answer 22

5 μm thick slices

Question 23

For light microscopy, tissue is preserved in ……….., which is what?

Answer 23

Formalin

Formaldehyde in physiological saline.

Question 24

Why is formaldehyde used in fixation?

Answer 24

Adds methyl groups and cross-links proteins to prevent degradation. Fixes proteins in their position.

Question 25

What techniques can be used for taking a tissue sample of endometrium?

Answer 25

• Endometrial biopsy
  > curettage
  > pipelle
• Hysterectomy (removal of uterus)

Question 26

What is the most routine staining method?

Answer 26

Haematoxylin and Eosin

Question 27

What parts of the cell do haematoxylin and eosin stain and what colours?

Answer 27

Haematoxylin - stain the nucleus blue

Eosin - stains the cytoplasm and ECM pink

Question 28

Compare paraffin wax/formalin fixation with frozen sections

Answer 28

Frozen sections can use fresh tissue
Frozen sections are much faster to prepare
Paraffin/formalin sections are permanent
Paraffin/formalin sections are much clearer

Paraffin/formalin sections used in pathological diagnosis
Frozen sections used in intraoperative consultation

Question 29

What is immunohistochemistry?

Answer 29

Use of antibodies to image presence of certain proteins in cells.

Indirect - uses second antibody with enzyme that makes a coloured product
Fluorescent - primary antibody has a fluorescent tag

Question 30

When imaging, multiple images can be taken with a set distance between. Images can be analysed in …….. This is particularly useful for evaluating ……. diseases

Answer 30

3D, eye

Question 31

When culturing cells, what needs to be kept constant in the internal environment?

Answer 31

• Conc. of oxygen, carbon dioxide, salt and electrolytes
• Conc. of nutrients and waste products
• pH
• Temperature
• Volume and pressure of fluid

Question 32

What is a benefit of analysing cells in live culture?

Answer 32

Allows manipulation of the cells to determine their function

Question 33

What are some disadvantages of cell culture?

Answer 33

• Hard to maintain
• Expensive
• Dedifferentiation - can become a different cell type
• 3D architecture is lost without cells around them