Cell adaptation, degeneration, and death 1.

Explain what homeostasis is

ongoing maintenance of physical and chemical conditions in a cell

What is mannosidosis

deficiency in mannosidase, an enzyme. There are two types: alpha-mannosidosis and beta-mannosidosis.

Causes a toxic accumulation of carbohydrate molecules

What are the four most frequently affected cellular components by injury?

• dna

• ribosomes

• phospholipid bilayer

• mitochondria

name 7 things that can cause cell injury

• infectious agents

• genetic derangements

• immunological reactions

• oxygen deficiency

• toxins, drugs, chemicals

• physical agents (force)

• nutritional imbalances

What is hypoxia, what causes this

deficiency of oxygen

reduced blood flow, severe blood loss, inadequate oxygenation of blood due to cardiorespiritory failure

How does hypoxia cause cell injury ?

low o2 → less atp made → Na/K channels close → Na accumulates in cell → messed up osmolarity → possible cell lysis due to osmosis of water into cell

Name two types of genetic derangements and mechanisms of action

Chromosomal abnormalities

Base pair substitution

• alter proteins

  • enzymes, structural proteins, receptors

Give an example of a base pair substituion genetic derangement

sickle cell anaemia

What is oxidative stress?

accumulation of free radicals

• reactive oxygen species, unstable and bind to any molecule

• important targets are lipids, proteins, dna.

important in the action of drugs, radiation, again and normal metabolism.

What are the consequences of loss of calcium homeostasis, what causes this?

injurious agents cause increased Ca+ into cells

increased cytosolic Ca+ activates enzymes

• ATPase = decreased ATP

• phospholipase = decreased phospholipids

• endonuclease = nuclear chromatin damage

• protease = disruption of membrane and cytoskeletal proteins

What is cellular adaptation, what can cause this?

reversible changes in size, number, phenotype metabolic activity or functions of cells.

can have physiological or pathological causes

• eg stress, injury

Define atrophy.

List some possible causes.

reduction in size / number of cells, occurring after organ development

• pathological

disuse, denervation, reduced perfusion, poor nutrition, bad endocrine stimulation, senility, pressure.

What are the mechanism of atrophy

reduced protein synthesis, increased protein degradation, reduction in cellular organelles and cytoskeletal proteins, apoptosis.

Define involution

reduction in size and number of cells, after organ development. physiologic atrophy

Define hypotrophy

reduction in size and number of cells, during organ development

Define aplasia

absence of an organ during organ development, with primordium present.

Define agenesis

absence of an organ during organ development due to lack of primordium

Define hypertrophy

increase in size of cells with :

• no cell division

• no new cells

• often accompanied by hyperplasia

• when limit is reached, degeneration occurs.

what causes hypertrophy, what are the mechanisms of this?

increased functional demand

• skeletal muscle

• endocrine cells

mechanisms

• increased cellular organelles

• increased synthesis of growth factor

What is hyperplasia, what caused this, what is the mechanism?

increase in no of cells, only in cells that can divide. increased mitotic activity.

• cells proliferate in response to hormones / growth factors

• can be caues by inflammation, physical trauma

give examples of hormonal hyperplasia and compensatory hyperplasia

hormonal -

• eg proliferation or mammary and uterine epithelium during pregnancy

compensatory -

• with partial loss of parenchyma

• in symmetrical organs with functional loss of one organ.

List three triggers for pathological hyperplasia

1. excessive hormone production or effect of growth factors, eg cystic endometrial hyperplasia

2. attempt of regeneration, eg nodular hyperplasia in spleen, liver, pancreas

3. with viral infections eg papilloma