Cellular Adaptions Flashcards
A 67-year old man presents with breathlessness on exertion and palpitations. On examination he is found to have a mid-systolic murmur heard best over the apex of the heart.
Mitral valve stenosis is suspected and this is confirmed by echocardiography.
Which of the following is most likely to be seen in this condition?
A) left atrial hypertrophy B) left ventricular atrophy C) left ventricular hypertrophy D) right atrial hypertrophy E) right ventricular atrophy
A) left atrial hypertrophy
In mitral valve stenosis (narrowing of the orifice of the mitral valve) the left atrium has to work harder to push the blood through the narrowed valve. As cardiac muscle is permanent tissue the left atrium will undergo hypertrophy and not hyperplasia.
Eventually, the increased pressure in the left atrium will be transmitted to the pulmonary vasculature which will result in right ventricular hypertrophy, but this is not an answer choice.
In pure mitral stenosis, left ventricular hypertrophy is not seen.
There is no reason for the myocardium to undergo atrophy.
Some cellular adaptations and changes predispose to neoplasia. Which of the following cellular adaptations generally do NOT predispose to neoplasia?
(There may be more than one correct answer)
A) atrophy B) dysplasia C) metaplasia D) hyperplasia E) hypertrophy
A) atrophy and E) hypertrophy
All neoplastic cells have changes to their DNA. DNA mutations commonly occur during DNA replication. Cellular adaptations that involve repeated cell division therefore predispose to neoplasia.
Hence, hyperplasia and metaplasia predispose to neoplasia.
In dysplasia, cell division is also occurring and the cells (or at least their maturation) are already abnormal. Some genetic changes are often present in dysplasia and it is frequently a pre-cancerous condition.
Cellular division is not occurring in atrophy and hypertrophy and these two conditions most usually do not predispose to malignancy.
When the cellular environment changes, cells may need to adapt in order to survive. Which one of the following is an adaptive response?
A) aplasia B) atresia C) dysplasia D) hypoplasia E) metaplasia
E) metaplasia
Metaplasia is an adaptive response whereby one differentiated cell type is replaced by another more suited to the altered environment.
The other options are not adaptive responses.
- Aplasia is the complete failure of a tissue or organ to develop
- Atresia is the congenital imperforation of an opening.
- Dysplasia is the abnormal maturation of cells within a tissue
- Hypoplasia is the congenital underdevelopment or incomplete development of a tissue or organ
Heart of 72 year old man shows left ventricular hypertrophy. Man suddenly died at home.
Which of the following is most likely to cause this appearance? A) mitral valve regurgitation B) mitral valve stenosis C) pulmonary hypertension D) pulmonary valve stenosis E) triscupid valve stenosis
A) mitral valve regurgitation
The commonest causes of left ventricular hypertrophy are systemic hypertension, ischaemic heart disease, aortic stenosis, aortic regurgitation, mitral regurgitation (the answer to this question), hypertrophic cardiomyopathy and exercise.
In mitral regurgitation the mitral valve is incompetent and during systole, as well as blood being ejected through the aortic valve, some will pass back into the left atrium through the incompetent mitral valve. The left ventricle will therefore have to work harder to maintain the systemic blood pressure and left ventricular hypertrophy is the result.
- Mitral valve stenosis leads initially to left atrial hypertrophy
- Pulmonary hypertension and pulmonary valve stenosis cause right ventricular hypertrophy
- triscupid valve stenosis cause right atrial hypertrophy
Inadequate blood supply creates a difficult environment for cells.
Which one of the following is most likely to be seen in response to an inadequate blood supply?
A) atrophy B) dysplasia C) hyperplasia D) hypertrophy E) metaplasia
A) Atrophy
A sudden complete loss of blood supply to a tissue would result in cell death and necrosis.
Partial but prolonged inadequate blood supply, however, causes atrophy.
A 56 year old lady undergoes a wide local excision for breast cancer. After her operation she is prescribed tamoxifen in order to decrease her risk of developing another breast cancer.
Which of the following is associated with this medication? A) atrophy of the endometrial glands B) hyperplasia of the breast epithelium C) hyperplasia of the endometrial glands D) hypertrophy of the breast epithelium E) metaplasia of the breast epithelium
C) hyperplasia of the endometrial glands
Tamoxifen is an anti-oestrogenic agent in the breast where it blocks oestrogen receptors and hence the proliferation action of oestrogen. For this reason it is used to prevent or treat breast cancer.
However, within the endometrium, tamoxifen has some oestrogenic activity and acts as an agonist at oestrogen receptors. Oestrogen receptor stimulation results in proliferation of the endometrium and this can cause endometrial hyperplasia.
A 28 year old woman has, against her GP advice, taken high dose prednisone for a year in order to ensure that she doesn’t have an asthma attack.
What change is likely to be seen in the woman’s adrenal glands?
A) atrophy
B) dysplasia
C) hyperplasia
D) hypertrophy
E) metaplasia
A) atrophy
The best way to shut down and atrophy an endocrine gland is to give high doses of the glands own hormone.
The administration of glucocorticoids, such as prednisolone, can suppress the hypothalamic-pituitary-adrenal pathway. The resulting drop in ACTH levels will cause the adrenal gland to atrophy.
A 42 year old man develops pain and swelling just beneath his jaw on the right side. This occurs at mealtimes. A CT scan demonstrates a stone in the duct of the right submandibular gland. The patient refuses treatment.
Which of the following is most likely to occur?
A) atrophy of the smooth muscle of the duct and atrophy of the parenchyma of the gland
B) atrophy of the smooth muscle of the duct and hyperplasia of the parenchyma of the gland
C) hypertrophy of the smooth muscle of the duct and atrophy of the parenchyma of the gland
D) hypertrophy of the smooth muscle of the duct and hyperplasia of the parenchyma of the gland
E) hypertrophy of the smooth muscle of the duct and metaplasia of the parenchyma of the gland
C) hypertrophy of the smooth muscle of the duct and atrophy of the parenchyma of the gland
When there is a blockage to the lumen of a duct, the smooth muscle within the wall of the duct will undergo hypertrophy (and to a lesser extent, hyperplasia) as it works hard to try and push the saliva past the obstruction.
Occlusion of the duct will also exult in atrophy of the parenchymal cells of the gland.
Metaplasia can be seen with salivary gland stones, but this is of the columnar epithelium lining the ducts when the epithelium changes to squamous epithelium in view of the chronic irritation caused by the stones.
Which of the following is an example of metaplasia?
A) changes to the mucosa of the small bowel in a patient with coeliac disease
B) glandular epithelium in the oesphagus of a patient with a hiatus hernia
C) increased number of goblet cells within the bronchi of a smoker
D) lactational change in the epithelium of breast during late pregnancy
E) secretory changes in the endometrial epithelium of a woman taking progesterone for contraception
B) glandular epithelium in the oesphagus of a patient with a hiatus hernia
- Barrett’s oesphagus is metaplasia of the squamous epithelium of the oesphagus to glandular epithelium. It is seen with persistent acid reflux such as occurs with a hiatus hernia.
- In coeliac disease there are inflammatory changes in the mucosa of the small bowel and villous atrophy
- Goblet cell hyperplasia is seen in smokers with COPD
- Lactational change in the breast is a physiological response seen in late pregnancy and after childbirth. The breast epithelial cells start to secrete milk but they do not undergo metaplasia.
- Secretory change under the influence of progesterone is similar in that the endometrial epithelial cells start to secrete a glycogen-rich secretion after ovulation but they do not undergo metaplasia.
Which of the following will arrest the cell cycle?
A) activation of the restriction point
B) binding of a cyclin to a cyclin-dependent kinase (CDK)
C) decreased production of CDK inhibitors
D) dephosphorlyation of the retinoblastoma susceptibility (RB) protein
E) reduced expression of p53 protein
A) Activation of the restriction point
- Activation of the restriction point (one of the cell cycle checkpoints) indicates that the cell has sensed some damage to it’s DNA. This results in increased transcription of the p53 protein. This protein delays the cell cycle and attempts to repair the DNA. If this is not possible the cell will undergo apoptosis.
- CDKs become activated when they bind to cyclins. Once activated, they will phosphorylate proteins such as the RB protein and these proteins push the cell through the cell cycle
- CDK inhibitors will slow down the cell cycle. If less of them are present the cell cycle will progress more quickly.
- The RB protein needs to be phosphorylated not dephosphorylated in order for the cell cycle to progress.
- p53 protein halts the cell cycle. If less is present the cell cycle will progress more quickly.
