Lecture One Flashcards
(28 cards)
What are the two categories of stress we experience?
Pathologic: Ischemia
Ischemia is a condition in which the blood flow (and thus oxygen) is restricted or reduced in a part of the body)
Physiologic: Pregnancy
What are the three cellular responses to stress?
ADAPTION: this is a reversible change in response to stress.
INJURY: injury can be both reversible and irreversible.
CELL DEATH
Normal- adaptation- injury -death
What are the four different cellular adaptions?
HYPERTROPHY- increase in the cell size
HYPERPLASIA- increase in cell number and often occurs in hypertrophy.
ATROPHY- decrease in cell size.
METAPLASIA- change in phenotype
-replacement of one differentiated somatic cell type with another differentiated somatic cell type in the same tissue.
-most prevalent examples: conversion of fibrous tissue into bone or columnar mucosal epithelium into stratified squamous epithelium.
What is hypertrophy?
-increase in cell size
this is achieved by having more protein and filaments.
-may occur together with hyperplasia (increase in cell number)
-muscle tissue: hypertrophy with more workload
Hypertrophy refers to an increase in the size of individual muscle fibers, whereas hyperplasia refers to an increase in the number of muscle fibers. Research over the past 40 years has shown that the predominant mechanism for increasing muscle size is hypertrophy.
Muscle cells which undergo both: cardiac muscle, skeletal muscle and nerves.
Give examples of hypertrophy?
Best example of hypertrophy:
LEFT VENTRICULAR HYPERTROPHY: thickening of the wall of the hearts main pumping chamber.
Thickening results in the evaluation of pressure within the heart and poor pumping action.
Most common cause is high blood pressure.
You would have an increased workload.
Physiologic examples: body builders and uterus in pregnancy.
Physiological and pathologic examples of hypertrophy?
PHYSIOLOGIC EXAMPLES:
- body examples (muscle hypertrophy for use)
- uterus in pregnancy (hormone driven change)
PATHOLOGIC EXAMPLES:
- left ventricular hypertrophy
- response to hypertension or increase workload.
What is hyperplasia?
-increase in cell number
-mostly caused by an excess stimulation.
PHYSIOLOGIC OR PATHOLOGIC
- it can be accompanied by hypertrophy,
Give three examples of physiologic hyperplasia?
BREAST GROWTH AT PUBERTY:
-hyperplasia and hypertrophy of glandular epithelial cells.
LIVER REGENERATION:
- partial liver donation this would result in the liver growing back to full size.
-hyperplasia of remaining hepatocytes
BONE MARROW:
-anemia- hyperplasia of red cell precursors
ERYTHROID HYPERPLASIA -condition of excessive count of erythroid precursor cells in the bone marrow- this condition would cause anaemia.
-red blood cell production may increase by 8x.
Give three examples of pathologic hyperplasia?
- ENDOMETRIAL HYPERPLASIA:
growth due to estrogen. - PROSTATIC HYPERPLASIA:
excessive response to androgens. - HUMAN PAPILLOMA VIRUS:
skin warts (epidermal hyperplasia)
genital warts (mucosal hyperplasia)
What is a malignancy? What are the effects of malignancy?
MALIGNANCY: a term for disease in which abnormal cells divide without control and can invade nearby tissues .
-oftens develops from hyperplasia
-increased cell division
-more chances for error in cell cycle control.
-uncontrolled growth
What are the most common cancer in males and females?
MALE:
1. breast
2. prostate
3. lung and bronchus
FEMALE:
1. breast
2. prostate
3. lung and bronchus
What is benign prostatic hyperplasia?
-effect men when men get older.
-an enlarged prostate gland can cause uncomfortable urinary symptoms.
-pathologic hyperplasia- Hyperplasia is increased cell production in a normal tissue or organ. Hyperplasia may be a sign of abnormal or precancerous changes.
-does not lead to malignancy
What is the difference between hypertrophy and hyperplasia?
PERMANENT/NON-DIVIDING CELLS:
-myocytes, skeletal muscle cells, nerves
-permanent G0 state (“terminally differentiated”)
-hypertrophy
CELLS CAPABLE OF GROWTH/DIVISION:
-epithelial cells (GI tract, breast ducts, skins)
-commonly undergo hyperplasia
-may lead to dysplasia/cancer
What is atrophy?
-reduction in size of organ/tissue
-decrease in cell size and/or number of cells
What are the physiological examples of atrophy?
-embryonic structure (notochord)
-uterus after childbirth (loss of hormone stimulation)
-breast/uterus at menopause
Give four causes of pathologic atrophy?
- Unused skeletal muscle
-bed rest
-immobilisation (cast after fracture) - Cachexia
-poor nutrition - Decreased blood supply
senile atrophy of brain atherosclerosis. - Loss of innervation
Neuromuscular disorders
What are two atrophy mechanisms?
UBIQUITIN PROTEASOME PATHWAY:
-protein tagged by ubiquitin
-transported to proteasome for degradation.
AUTOPHAGY:
-self eating
-cellular components fused with lysosomes
What is metaplasia?
Why is it done?
What is the effect of it?
Change in cell type to adapt to stress.
New cell type to withstand stress.
Commonly from one epithelial cell type of another.
Potentially reversible
can lead to dysplasia/malignancy
Give an example of how metaplasia occurs in smokers?
RESPIRATORY TRACT IN SMOKERS:
-normal columnar epithelium in trachea/bronchi
-changes to squamous epithelium
-this change necessary because these are more durable.
In smokers the cilia was lost and this would mean that they are more vulnerable to infections
What is Barrett’s oesophagus?
This is a condition where the flat pink lining of the swallowing tube which connect the mouth and the stomach- this becomes damaged by acid reflux the lining would then become thicken and become red.
METAPLASIA- what are the pathologic changes happens during Barrett’s oesophagus?
The gastric acid would act as a stressor in the oesophagus.
This stress would cause the normal stratified squamous
to change to columnar epithelium
METAPLASIA:
What is myostitis ossificans (heterotopic ossification)?
This is where muscle metaplasia to bone.
This type of metaplasia would be:
mesenchymal cells would change to osteoblastic tissue.
Leads to lamellar bone in muscle.
This would occur after trauma (hip arthroplasty)
This cause the muscle to become stiff.
Why is vitamin A important and what does the deficiency lead to?
Vitamin A is important for maintaining the epithelial cells .
This deficiency leads to epithelial metaplasia and keratinisation.
UPPER RESPIRATORY TRACT:
Epithelial metaplasia will occur.
Epithelium will be replaced by the keratinising the squamous cells.
Abnormal epithelium can lead to pulmonary infections.
XEROPHTHALMIA (DRY EYES)
Normal epithelium secretes mucus
Replaced by keratinised epithelial cells.
What is apocrine metaplasia?
This is a fibrocystic change in breast.
Another name for apocrine metaplasia is benign epithelial alternation.
This can lead to changes in the lobular epithelial cells.
takes on the appearance of apocrine cells.
does not lead to dysplasia/cancer
