Exam Time: 45 minutes (1:05-1:50) Total points: 50 (each question carries 1 poin

Question

Exam Time: 45 minutes (1:05-1:50) Total points: 50 (each question carries 1 point) Use of electronic devices, talking, copying from others, will lead to a grade F in this exam. Please return the test at the end of the exam 1. Functions of the basement membrane include which of the following? a. Contractility b. Molecular filtering c. Active ion transport d. Excitability e. Modification of secreted proteins 2. Using immunohistochemistry a popalation of cells is shown to be positive for the protein connexin. From this we can infer that the cells are connected by what type of junction? a. Tight (occluding) junctions b. Zonula adherens -e. Gap junctions d. c. Desmosomes (macula adherens) 3. An individual genetically unable to synthesize normal occludin is likely to have epithelia with defective regulation in which of the following? a. Material crossing the epithelium between the cells (paracellular movement) b. Communication between the cells c. Attachment to the basement membrane d. Strong attachment to neighboring cells Movement of membrane proteins in the apical domains of cells e. 4. An intermediate filament protein found in cytoplasm of most epithelial cells is which of the following? a. Actin b. Vimentin c. Laminin d. Myosin e. Keratin 5. Which of the following cellular features is used in naming types of epithelia? a. Shape of cells in the basal layer b. Number of cell layers c. Presence of a basal lamina d. Size of the nuclei e. Nature of the cell junctions that are present 6. The release of lipid droplets from cells is which type of secretion? a. Merocrine b. Serous c. Apocrine d. Mucous e. Holocrine 7. Exocrine glands in which the acini all produce a secretion of heavily lycosylated, hydrophilie proteins are an a. Serous gland b. Mixed gland example of which type of gland? c. Mucous gland

Explanation / Answer

Ans 1: b.

Basement membrane acts as a filter between the epithelial layer and the connective tissues underlying it. In kidneys the glomerular basement membrane plays the role of a filter in the formation of urine.

Ans 2: c

Connexins are the core proteins in channels formed by gap proteins between adjacent cells.

Ans 3: a

Loss of Occludin affects the barrier properties and tight junction stability, impacting the paracellular movement of materials between the cells.

Ans 4: c

Laminin is protein of the extracellular matrix, significantly having high-molecular-weight.

Ans 5: b

Single layer of cells - Simple epithelium e.g. single layer of cuboidal cells - Simple cuboidal epithelium.

Three layers of cells - Stratified epithelium e.g three layers of cuboidal cells - stratified cuboidal epithelium.

Three layers of cells followed by ten more - stratified squamous epithelium e.g. three layers of cuboidal and ten layers of of squamous cells - stratified squamous cells.

Ans 6: c

As per known physiology. e.g. apocrine glands secrete fat droplets in breast milk and those in the ear form wax.

Ans 7: c

As per proven anatomy and physiology.

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