Principles of Histology I

Question 1

Define cell

Answer 1

Building blocks of a living organism

Question 2

Define histology and how is it different from cytology.

Answer 2

• Microscopic study of tissues and organs
• CYTOLOGY - examination of a single cell type

Question 3

What must happen to a cell before being viewed under a microscope?

Answer 3

• Sectioned and stained

Question 4

What do microscopes do to images?

Answer 4

• Magnify
• Resolve

Question 5

How do light microscopes work?

Answer 5

Light passed through sample from a light source
- Image magnified by objective lens and viewed through eyepiece lens

Question 6

How are tissue biopsies prepared?

Answer 6

• Sample taken
• Dipped in embalming liquid to prevent decomposition
• Embedded in wax - allows slicing of tissue usiing a microtone
• Stained, slide set up and viewed under microscope

Question 7

What are three types of histological sections?

Answer 7

• Cross section
• Longitudinal
• Oblique

Question 8

What is the freeze fracture technique used for?

Answer 8

• Cells frozen using liquid nitrogen and sliced
• Can be used to visualise extracellular and cytoplasmic layers

Question 9

What is the purpose of the fluid mosaic model and what does it suggest?

Answer 9

• Not possible to see plasma membrane in vivo
• Model aids understanding of how membrane works
• Suggests membrane is dynamic and bilayer acts as a fluid in which molecules are suspended

Question 10

What is the cytoplasm and what is it composed of?

Answer 10

• Cellular material outside nucleus but within plasma membrane
• Cytosol - fluid part containing proteins, cytoskeleton
• Organelles

Question 11

What is the purpose of the cytoskeleton?

Answer 11

• Supports cell
• Holds organelles in place
• Responsible for changes in cell shape

Question 12

Describe and identify the three cytoskeletal filaments.

Answer 12

• Microfilaments (ACTIN) - organised in muscle tissue
• INTERMEDIATE - found in skin cells (flexible and strain resistant)
• MICROTUBULES - involved in chromosome segregation and flagella/cilia movement
• FILAMENTS anchored by desmosome

Question 13

Outline the purpose and nature of centrioles.

Answer 13

• Made up of microtubules in the centrosome
• Arranged perpendicularly
• Influence cell division and motility

Question 14

Describe the general structure of the ER.

Answer 14

• Broad, interconnected sacs
• Continuation of nuclear envelope

Question 15

Describe RER.

Answer 15

• Ribosomes attached
• Modify proteins synthesised at ribosomes

Question 16

Describe SER.

Answer 16

• Involved in lipid synthesis
• Stores calcium ions in muscle cells

Question 17

Describe Golgi apparatus

Answer 17

• Formed of cisternae
• Modify proteins and lipids from ER and package into vesicles
• The addition of mannose-6-phosphate to proteins designates transport to lysosome

Question 18

Give two types of vesicles

Answer 18

• Secretory vesicles
• Peroxisomes - Catabolism of very long chain fatty acids and amino acids

Question 19

Describe the mitochondria

Answer 19

• Smooth outer and folded inner membrane with matrix containing enzymes and circular DNA
• Semi-autonomous - move around cytoplasm
• Numerous in cells with high energy requirements

Question 20

Describe mitochondrial DNA inheritance.

Answer 20

• Maternal
• Mutations transmitted from female carrier to offspring