PATH 201 - LECTURE 2

what are the types of cells based on cell division and proliferation

• labile

• stable

• quiescent cells

• permanent cells

what are labile cells

cells that multipy constantly thoughout life

what are stable cells

• cells that multiply in response to stress or tissue damage

what are quiscent cells

• cells that are in a reversible state when a cell doesnt divide but retains the ability to re-enter cell proliferation

• stuck in stage G0

what are permanent cells

• do not divide postnatally

what type of cell (based on proliferation) is epithelial cells

labile

what type of cell (based on proliferation) is a myocardial cell

stable

what type of cell (based on proliferation) is a satellite cell in muscle

quiscent cells

what type of cell (based on proliferation) is a liver cell

stable

what type of cell (based on proliferation) is a neuron

permanent

what type of cell (based on proliferation) is a adipocyte

permanent

what are the main causes of cellular stress

• oxygen deprivation

• physical trauma

• chemical trauma

• infectious agents

• immunological agents

• genetic derangements

• nutritional imbalances

what is the clincal term for oxygen deprivation

hypoxia

what is the clinical term for restriction of blood supply

ischaemia

describe ischaemia

• deprived of o2

• waste products cannot be removed

• accumulation leads to pain

describe the basic path of oxygen from the atmosphere to the cells

• enters the lungs from the atmosphere and moves into the blood vessels

• haemoglobin inside the RBCs pick it up and transport the O2 to the cells

• haemoglobin goes around transporting iti

what are the forms of hypoxia

hypoxic hypoxia

anaemic hypoxia

ischaemic hypoxia

describe hypoxic hypoxia

• isufficient oxygen available in the lungs

• the lungs are not able to deliver enough oxygen to the blood passing through them

what are common causes of hypoxic hypoxia

• drowning

• blocked airway

• reduced oxygen in the atmosphere (at a high altitude)

• general lung damage>hypoxia is a secondary effect

describe anaemic hypoxia

• decreased concentration of functional haemoglobin or red blood cells

what are common causes of anaemic hypoxia due to decreased conc of haemoglobin

• sick cell anaemia

• thalassemia

what are common causes of anaemic hypoxia due to decreased RBCs

• decreased producton

• increased or early degeneration

describe ischaemic hypoxia

• inadequate blood supply to the tissues

what are the 4 types of ischaemic hypoxia

• generalised

• localised

• gradual

• acute

what causes generalised ischaemic hypoxia

heart failure

what causes localised ischaemic hypoxia

vessel obstruction

what causes gradual ischaermic hypoxia

arteriosclerosis (gradual build up of plaques in arteries)

what causes acute ischaemic hypoxia

• embolus

• infarction

what are some examples of physical cell trauma

• mechanical

• thermal (hypo and hyperthermia)

• electrical

• radiation

• changes in atmospheric pressure

what are some examples of chemical trauma on cells

• hypertonicity

• posions

• strong acids and alkali

• environmnetal pollutants

• recreational drugs

describe the effects of MDMA on cells

• increases serotonin release by neurons

• serotonin is involves in temperature regulation

• increased temperature>increased water consumption

• cells swell and burst and die

what are some examples of infectious agents that affect cells

• fungi

• viruses

• parasites

• protozoa

• bacteria

what are examples of immunological agents

• allergies

• autoimmunity

what are some example of immunological agents that cause cellular stress

• hypersensitivity reaction

• anaphylactic reaction

what are examples of genetic derangements that cause cell stress?

• mutations

• Mendelian single-gene disorders

what are soem examples of mutations that cause cell stress

• point mutations

• indels

• trinucleotide repeat mutations

what are some medelian single gene disorders that cause cell stress

• autosomal dominant

• autosomal recessive

• x linked

what is an example of an autosomal dominant mendelian single gene disorder that causes cell stress

• huntington

what is an exmaple of an autosomal recessive mendelian single gene disorder that causes cell stress

cystic fibrosis

what is an example of an x linked mendelian single gene disorder that causes cell stress

duchennes muscular dystrophy

what is thalassemia

• inherited mutations that decrease the rate of alpha or beta globin chains leading to haemoglobin deficiency

what usually causes alpha thalassemia

deletion of part of the alpha globin gene

what usually causes huntingtons disease

• repeat expansion of CAG in the huntingtons disease gene

what causes earlier onset of huntingtons

• increased number of repeats

what does huntingtons do

• destroys medium spiny striatal neurons that dampen motor activity

excess of what minerals can cause cell stress

• carbs

• fats

• vitamins

• minerals

what are the 3 main paths of responses to cell stress

adaptation

injury

death

what are the types of adaptation

• hypertrophy

• hyperplasia

• metaplasia

• atrophy

what is hypertrophy

• increase in size of individual size adn therefore the organ

what is hypertrophy associated with

• increased accumulation of protein

• not an increase in cellular fluid

what does hypertrophy usually happen in response to

increased workload on the organ

what organs are susceptible to hypertrophy

heart and kidneys

what is hyperplasia

• increase in the number of cells which is caused by an increase in cell division

what generally causes hyperplasia

• occurs in response to severe and prolonged cell death

what are the 3 types of hyperplasia

• compensatory

• hormonal

• pathological

what is compensatory hyperplasia

Cells divide to replace tissue that has been lost or damaged. For example, the liver regenerates after part of it is removed.

what is hormonal hyperplasia

Hormones stimulate cells in responsive organs to multiply. Examples include:

• normal breast gland growth during pregnancy;

• endometrial growth under estrogen stimulation.

what is pathological hyperplasia

• Excessive hormonal or growth-factor stimulation causes abnormal proliferation

• for example, endometrial hyperplasia from prolonged unopposed estrogen.

what is metaplasia

• reversible replacement of one mature cell type by another cell differentiated cell

• e.g., columnar replaced with squamous

what is barretts oesophagus

• a condition in which ongoing reflux from the stomach causes long term stress on epithelia in the oesophagus

• squamous cells > coloumnar cells

• metaplastic

what is atrophy

• reduction in cell size due

what is the mechanism behind atrophy

• increased protein degradation and decreased protein synthesis

what can atrophy result in (effect on organs)

shrinkage

what changes to the cell (other than reduced size) does atrophy cause

• reduced ER

• reduced mitochondria

• reduced myofilaments

what are causes of atrophy

• decreased workload

• decreased use

• decreased blood supply

• decreased nutrition

• decreased hormonal stimulation

• decreased nervous stimulation

• aging

what is poliomyelitis

• caused by a virus

• atrophy of the limbs due to damage to anterior horn motor neurons

what are the two types of cell injury

reversible and irreversible

what determines if damage/injury is reversible

• if the stress if of short duration

• once the duration of stress passes a threshold, we start to see irreversible cell injury