Lecture 19

Question 1

What factors affect cells and tissues ability to adapt?

Answer 1

1. State of differentiation (3 types - labile, stable or permanent) 2. Particular vulnerability to certain agents 3. Blood supply 4. Nutrition 5. Previous state of the cell

Question 2

What are adaptive changes:

Answer 2

Reversible changes in mature cells and tissues after growth has occurred.

Question 3

Define the term atrophy:

Answer 3

A reduction in the size or amount of the organ, tissue or cell. This is due to a decrease in the size and/or number of specialized cells or organelles. This can be physiological or pathological

Question 4

Describe the mechanism behind atrophy occurring:

Answer 4

Increase in apoptosis is responsible for decrease in number of cells. The remaining cells survive at a small size - fewer mitochondria, myofilaments and ER. The reduction in cell size is associated with catabolism > anabolism

Question 5

What are the causes of atrophy (provide one pathological and one physiological)?

Answer 5

Pathological: inadequate nutrition and decreased blood supply Physiological: decreased workload (disuse)

Question 6

What process has occured in this histological slide and how can you tell?

Answer 6

Muscle atrophy - nuclei look more concentrates and each nuclei will also look a little bit more plump

Question 7

Define the term hypertrophy:

Answer 7

Increase in the size of an organ or tissue due to an increase in the size of its specialised cells

Question 8

What types of cells will hypertrophy typically occur in?

Answer 8

Cells with an increased workload that cannot divide e.g. muscle

Question 9

What is the appearance of hypertrophic cells on a histological slide?

Answer 9

General increase in the number of organelles which increases the size of the cell (limited by SA: vol ratio)

Question 10

Provide an example of compensatory and hormonal hypertrophy:

Answer 10

Compensatory: removal of a kidney, increased workload - striated and cardiac muscle

Hormonal: pregnancy causing uterine hypertrophy

Question 11

What are the mechanisms of hypertrophy?

Answer 11

Trophic triggers: growth factors, hormones, cytokines. May be produced endogenously or exogenously causing increased gene expression

OR

physical triggers - e.g. pressure stretching on the cell membrane

Question 12

Name the two processes occuring in the image below:

Answer 12

1. Left ventricular concentric hypertrophy
2. Left ventricular dilation/eccentric hypertrophy

Question 13

What is meant by the term hyperplasia?

Answer 13

An increase in the size of an organ or tissue due to an increase in the number of specialised cells. May be due to physiological or pathological causes.

Question 14

Provide an example of physiological hyperplasia and an example of pathological hyperplasia:

Answer 14

Physiological hyperplasia: haematopoetic system after blood loss, mesentric lymph nodes

Compensatory/reactive: cyclical changes in mammary gland or endometrium

Pathological hyperplasia: hormonal excess - XS erythropoietin, XS estrogen, reparatory - to restore architecture or function, infectious organisms

Question 15

Define the term metaplasia:

Answer 15

change from one type of specialised fully differentiated adult cell to another adult cell type (often less specialised)

Question 16

Why does metaplasia normally occur?

Answer 16

generally metaplasia is a protective response - often a response to a chronic irritant

Question 17

How does metaplasia generally occur?

Answer 17

reprogramming of stem cell by cytokines, growth factors (TGF-B), ECM components

Question 18

Define the term dysplasia:

Answer 18

It is disordered growth that generally occurs in the epithelium. It often occurs in metaplastic/hyperplastic epithelium. This results in a loss in uniformity of individual cells plus losses in architectural organisation. It may progress to neoplasia.