L2 - Cell Growth and Adaptation

Question 1

Cell and tissue growth types

Answer 1

• Multiplicative (Increase in number of cells)
• Auxetic (Increased size of individual cells, e.g. growing muscle)
• Accretionary (Increase in intracellular tissue components, e.g. bone & cartilage)
• Combined (All of the above occur – different rates and direction of growth at different sites e.g. embryological development)

Question 2

Tissue growth depends on balance between:

Answer 2

• balance between cell proliferation and apoptosis

- differentiation – cells differentiate to perform specialized roles

Question 3

Normal growth patterns

Answer 3

Labile

• very high regenerative ability & rate of turnover.
• E.g. skin epithelial cells

Stable

• good regenerative ability but usually a low rate of turnover.
• E.g. liver, muscle

Permanent

• Limited regenerative ability
• E.g. neurons

Question 4

Factors affecting differentiation

Answer 4

• Genes
• Hormones
• Position within fetus
• Growth factors
• Matrix proteins

Question 5

Morphogenesis

Answer 5

• Development of the shape and form of organs, limbs, facial features etc., from primitive cell masses during embryogenesis
• Involves growth and differentiation, movement of cell groups and apoptosis

Question 6

Adaptation ( when cells are constantly exposed to changing environment)

Answer 6

• Normal physiology (physiological stimuli)

- Abnormal/disease (pathological stimuli)

Question 7

Adaptation (Physiological metabolic adaptations)

Answer 7

• Fasting: mobilize fatty acids from adipose tissue – energy
• Lack of calcium: mobilize calcium from bone matrix –
  blood Ca++
• Drugs – metabolized by live

Question 8

Adaptation (Physiological structural adaptations)

Answer 8

• Increased cellular activity – increase in size or number of cells
• Decreased cellular activity – decrease in size or number of cells
• Alteration of cell morphology – cell differentiation

Question 9

Examples of Physiological adaptations

Answer 9

• Increased muscle bulk, strength and endurance
• Improved respiratory and cardiovascular functions with exercise
• Increase in red blood cell numbers when living at higher altitudes to compensate for lack of oxygen

Question 10

Examples of Pathological adaptations

Answer 10

• Modifications that allow the cells to cope with changed conditions
• Introduce structural and functional features to the body (manifestations of a disease state)
• Often caused by abnormality or disease in another body system

Question 11

Hyperplasia & Hypertrophy

Answer 11

• hyperplasia : an increase in the number of produced cells
• hypertrophy: an increase in the size and functional capacity of cells
• (hyperplasia and hypertrophy usually coexist)

Question 12

Atrophy

Answer 12

a decrease in the mass of cells

Question 13

Metaplasia

Answer 13

a change in the structure of cells to suit new changes

Question 14

Apoptosis

Answer 14

normal and programmed cell death

Question 15

Necrosis

Answer 15

cell death caused by injury or disease

Question 16

Types of necrosis

Answer 16

• coagulative
• liquefactive
• caseous

Question 17

Liquefactive necrosis

Answer 17

• enzyme digestion is the main process
• a combination of autolysis and lysosomal enzymes released by WBCs
• seen in areas of bacterial infection and brain necrosis produced by hypoxia/ischaemia

Question 18

Caseous necrosis

Answer 18

• a ‘cheesy’ looking coagulative change caused by tuberculosis and some infective agents

Question 19

Physiological hyperplasia and hypertrophy examples

Answer 19

Physiological hyperplasia and hypertrophy in the breasts of a pregnant woman

Physiological hyperplasia of red blood cells for those living at a high altitude (compensation for lack of oxygen)

Question 20

Pathological hyperplasia and hypertrophy examples

Answer 20

Pathological cardiac hypertrophy due to myocardial infarct (left ventricular hypertrophy as the ventricle tried to compensate for inefficient blood flow)

Pathological parathyroid hyperplasia (renal failure leads to a lack of calcium, calcium is in demand, so there is hyperplasia of the parathyroid gland to compensate for low calcium)

Question 21

Physiological atrophy examples

Answer 21

Physiological atrophy due to old age (atrophy of bone, gums, cerebrum, testes due to reduced gonadotrophic stimulation)

Question 22

Pathological atrophy examples

Answer 22

Pathological atrophy due to disuse (e.g. fracturing a leg and not walking on it for a long time)

Pathological atrophy due to loss of innervation (e.g. nerve transection, polio)

Question 23

Pathological necrosis examples

Answer 23

Brain necrosis or cardiac necrosis due to hypoxia or myocardial infarct

Question 24

Physiological metaplasia examples

Answer 24

Metaplasia of cervical epithelium from columnar to squamous cells with age and puberty

Question 25

Pathological metaplasia examples

Answer 25

Metaplasia of bronchial respiratory epithelium due to smoking or chronic irritation