Disorders of growth, differentiation and morphogenesis

Question 1

Types of growth

Answer 1

Multiplicative: increase in number of cells by mitosis.

Auxetic: increased size of individual cells (skeletal muscle)

Accretionary: increase in intracellular tissue components (bone)

Combined patterns: embryological development.

Question 2

Cell types based on regenerative ability

Answer 2

Labile (very high reg.) intestine

Stable (good regen, low turnover) hepatocytes

Permanent (no) neurones

Question 3

What does the M phase comprise of?

Answer 3

Nuclear division (mitosis) + cytoplasmic division (cytokinesis)

Question 4

Totipotent

Answer 4

Able to form all of the cells of the embryo and placenta

Question 5

Pluripotent

Answer 5

Producing all cells from endo-, meso-, and ectoderm.

Question 6

Multipotent + Unipotent

Answer 6

Generates small number of cell types or only one.

Question 7

Hypertrophy

Answer 7

Increase in cell size without cell division

Question 8

Hyperplasia

Answer 8

Increase in size by increasing the number of cells by mitosis.

Also a decrease in apoptosis.

Question 9

Physiological examples of hypertrophy

Answer 9

Muscles in athletes (skeletal and LV)

Question 10

Physiological examples of hyperplasia

Answer 10

Bone marrow cells in high altitudes.
Breast tissue in pregnancy.
Thyroid - increased metabolic demand (pregnancy)

Question 11

Physiological example of hypertrophy and hyperplasia (mixed)

Answer 11

Uterine smooth muscle by oestrogens.

Question 12

Disease marked by epidermal hyperplasia

Answer 12

Psoriasis

Question 13

Hyperplasia of osteoblasts and osteoclasts resulting in thick but weak bone

Answer 13

Paget’s disease

Question 14

Autonomous proliferations of myofibroblasts - forming tumour like masses

Answer 14

Fibromatoses

Question 15

Angiogenesis can take place by…

Answer 15

Sprouting

Intussusception

Circulating stem cells recruited to the site of hypoxia.

VEGF and MMP

Question 16

Vascular endothelial cells and myofibroblast hyperplasia…

Answer 16

Important components of repair and regeneration.

Question 17

Athropy

Answer 17

Decrease in size of an organ or cell

Question 18

Atrophy may be..

Answer 18

Physiological - post menopause
Pathological - immobilisation of limbs = muscle atrophy. Loss of innervation etc.

Question 19

Pressure atrophy

Answer 19

Bed sores (exogenous)
Tumour compresses against BV (endogenous)

Question 20

Cachexia

Answer 20

Severe starvation (systemic atrophy) influenced by CKs and TNF.

Question 21

Hypoplasia

Answer 21

Failure of development of an organ.
Related to atrophy
Failure of morphogenesis

Question 22

Example of hypoplasia

Answer 22

Failure in the development of the legs in severe spina bifida PTs.

Question 23

Metaplasia

Answer 23

Acquired form of altered differentiation (one mature differentiated cell into another)

Response to altered cellular environment.

Affects epithelial and mesenchymal cells

Increased risk of malignancy.

Question 24

Examples of metaplasia

Answer 24

Respiratory epithelium of trachea and bronchi to squamous epithelium.

Bladder epithelium to simple squamous in the presence of stone and ova of Schistosoma haematobium.

Question 25

Example of glandular metaplasia

Answer 25

Barrett's oesophagus from squamous epithelium to columnar glandular epithelium (glandular metaplasia).

Question 26

Examples of mesenchymal metaplasia

Answer 26

Osseous metaplasia - Ca deposition in atheromatous arterial walls - bronchial cartilage

Question 27

Congenital disorder

Answer 27

Present at birth.

Question 28

Autosomal chromsome trisomy

Answer 28

21 Down's syndrome 18 Edward's syndrome 13 Patau's syndrome (microcephaly, cleft lip and cleft palate) die in first year.

Question 29

Sex chromosomal abnormalities

Answer 29

Klinefelter's 47 XXY: testicular atrophy, geynaecomastia (varients 48 XXXY, 49 XXXXY, 48 XXYY) Double Y males 47 XYY Turner's syndrome 45 X: short stature, amenorrhoea and infertility. Multiple X females: 47 XXX, 48 XXXX mental retardation. Hermaphrodites (true) 46 XX, 46XX, 47XXY both testicular and ovarian tissue.

Question 30

Loss of part of a chromosome

Answer 30

Cri-du-chat syndrome (46XX 5p-) deletion of short arm of chromosome 5.

Question 31

Three categories of single gene disorders

Answer 31

Enzyme defects: albinism lack of melanin, galactose-1-phosphate uridyl transferase deficiency. Receptor or cellular transport defect: lack on androgen receptor = insensitivity. CF no membrane transport. Non-enzyme protein defects: sickle cell anaemia. Marfan's and Ehlers-Danlos defective collagen production.

Question 32

Deformation or disruption

Answer 32

Anomalies of normal development caused by extrinsic physical forces.

Question 33

Malformations

Answer 33

Intrinsic failures of morphogenesis, differentiation or growth.

Question 34

Kartagener's syndrome

Answer 34

Defect in ciliary motility due to absent or abnormal dynein arms -> situs inversus.

Question 35

Hirschsprung's disease

Answer 35

Marked dilation of the colon and failure of colonic motility = absence of Meissner and Auerbach's nerve plexuses.

Question 36

Cryptorchidism

Answer 36

Failure of testis to migrate to its normal position.

Question 37

Agenesis

Answer 37

Failure of development of an organ or structure within it. Renal - few days of survival Thymic - DiGeorge (poor T-cell production) Anencephaly - lethal

Question 38

Atresia

Answer 38

Failure of the development of a lumen in a normally tubular structure. Oesophageal - fistulae Biliary atresia - obstructive jaundice in early childhood. Urethral atresia.

Question 39

Hypoplasia

Answer 39

Failure of an organ to attain its normal size. Osseous nuclei of the acetabulum= congenital dislocation of the hip due to the flattened roof to the acetabulum.

Question 40

Maldifferentiation (dysgenesis)

Answer 40

Failure of normal organ differentiation or presistence of primitive embryological structures.

Question 41

Ectopia

Answer 41

Development of mature tissue in an inappropriate site. Endometriosis Merkel's diverticulum

Question 42

Neural tube defects are due to what?

Answer 42

Dietary deficiency of folate.

Question 43

Spina bifida

Answer 43

During 4th week the neural tube is formed by invagination of the dorsal ectoderm. Failure of the neural tube to invaginate fully / the overlying ectoderm to close afterwards results in defects = exposed cord.

Question 44

Cleft palate

Answer 44

Occur in the first 9 weeks = from about 5 weeks the maxillary processes grow anteriorly and medially - fuse with the fronto-nasal process at two points just below the nostrils= upper lip. Palate develops from palatal processes of maxially processes and fuse with the nasal septum. Failure of this results in cleft palate.