IMS1 Introduction to Medical Sciences 1 - Practice Flashcards

This flashcard set covers the IMS1 module topics including early embryology, cellular biology, metabolism, pharmacology, and oncology genetics for Brunel MBBS students.

Ampulla

The specific site in the fallopian tube where fertilisation of the oocyte occurs.

Acrosome Reaction

Process by which sperm penetrate the corona radiata and zona pellucida using enzymes such as hyaluronidase and acrosin.

Morula

A solid ball consisting of $16-32$ cells, still contained within the zona pellucida, formed by rapid mitotic divisions known as cleavage.

E-cadherin

The protein responsible for compaction at the 8-cell stage, allowing blastomeres to adhere tightly together.

Blastocyst

An embryonic stage characterized by a fluid-filled cavity (blastocoele) and the emergence of the inner cell mass (embryoblast) and the outer trophoblast layer.

Syncytiotrophoblast

The outer, multinucleated, and invasive layer of the trophoblast that secretes $hCG$ to maintain the corpus luteum.

Gastrulation

A process occurring between days 15–17 where the bilaminar disc becomes a trilaminar disc, establishing the three germ layers: ectoderm, mesoderm, and endoderm.

Notochord

A midline mesodermal rod derived from prechordal mesoderm that acts as the primary inductor for the formation of the neural tube.

Anencephaly

A neural tube defect that occurs when the anterior neuropore fails to close, resulting in the absence of the forebrain.

Sacrococcygeal Teratoma

The most common neonatal tumour, which can form if the primitive streak fails to regress by days 19–20.

Hutchinson-Gilford Progeria

A clinical condition caused by a mutation in lamin A, leading to a defect in the nuclear lamina.

$\alpha$-1 antitrypsin deficiency

A condition where mutant proteins fail to fold properly in the Rough Endoplasmic Reticulum ($RER$), accumulating and leading to emphysema and cirrhosis.

I-cell disease

A deficiency of N-acetylglucosamine-1-phosphotransferase where lysosomal enzymes lack the mannose-6-phosphate tag and are secreted instead of delivered to lysosomes.

Tay-Sachs Disease

A lysosomal storage disease caused by Hexosaminidase A deficiency, resulting in $GM2$ ganglioside accumulation and a cherry-red spot on the macula.

Zellweger Syndrome

A peroxisomal biogenesis disorder characterized by absent peroxisomes and the accumulation of very-long-chain fatty acids ($VLCFA$).

Kartagener's Syndrome

A type of primary ciliary dyskinesia caused by a dynein arm defect, presenting with immotile cilia, situs inversus, and bronchiectasis.

Chylomicrons

Lipoproteins that transport dietary triglycerides from the gut to tissues, containing apolipoprotein $B-48$.

Carnitine Shuttle

The transport mechanism required to move long-chain fatty acids across the inner mitochondrial membrane for beta-oxidation.

CPT-1 (Carnitine Palmitoyltransferase I)

The rate-limiting enzyme of beta-oxidation, which is inhibited by malonyl-CoA.

HMG-CoA Synthase

The rate-limiting enzyme in the liver mitochondria responsible for the production of ketone bodies.

AST:ALT Ratio > 2:1

A biochemical marker classically suggestive of alcoholic hepatitis.

Carbamoyl Phosphate Synthetase I (CPS I)

The rate-limiting mitochondrial enzyme of the urea cycle that requires N-acetylglutamate ($NAG$) as an essential activator.

Ornithine Transcarbamylase (OTC) Deficiency

The most common urea cycle defect, which is X-linked and results in hyperammonaemia and orotic aciduria without megaloblastic anaemia.

Phosphofructokinase-1 (PFK-1)

The rate-limiting enzyme of glycolysis, activated by $AMP$ and fructose-2,6-bisphosphate and inhibited by $ATP$ and citrate.

Von Gierke's Disease (Type Ia)

A glycogen storage disease caused by glucose-6-phosphatase deficiency, presenting with severe fasting hypoglycaemia and hepatomegaly.

McArdle Disease (Type V)

A deficiency in muscle glycogen phosphorylase characterized by an inability to perform strenuous exercise and the 'second wind' phenomenon.

Lesch-Nyhan Syndrome

An X-linked deficiency of $HGPRT$ in the purine salvage pathway, leading to hyperuricaemia, self-mutilation, and developmental delay.

Orotic Aciduria

A defect in pyrimidine synthesis resulting in orotic acid in urine and megaloblastic anaemia that does not respond to $B_{12}$ or folate.

p53

The 'guardian of the genome' that activates checkpoints in the cell cycle or triggers apoptosis in response to DNA damage.

Integrins

Alpha-beta heterodimeric cell adhesion molecules that bind the extracellular matrix and facilitate bidirectional signalling.

Volume of Distribution ($V_d$)

A pharmacokinetic parameter calculated as $\frac{\text{dose}}{\text{plasma concentration}}$, indicating the extent of drug tissue binding.

Zero-order Kinetics

Elimination of a constant amount of drug per unit time, regardless of plasma concentration, as seen with ethanol or aspirin at high doses.

TLR4

A pattern recognition receptor on the surface of innate immune cells that recognizes Lipopolysaccharide ($LPS$) from Gram-negative bacteria.

MHC Class II

Proteins expressed on professional antigen-presenting cells that present exogenous phagocytosed peptides to $CD4^+$ T cells.

Type III Hypersensitivity

Immune complex-mediated inflammation caused by the deposition of antigen-antibody complexes in tissues, such as in systemic lupus erythematosus ($SLE$).

BCR-ABL

A constitutively active tyrosine kinase resulting from the Philadelphia chromosome translocation $t(9;22)$, associated with chronic myeloid leukaemia ($CML$).

Synthetic Lethality

The clinical mechanism where $PARP$ inhibitors block single-strand break repair in cells already deficient in homologous recombination repair ($BRCA1/2$), leading to cell death.