Wk 3: Membranes make cells but not all cells are built the same

Question 1

Cell shape aiding cell function: muscle cells

Answer 1

• Elongated and cylindrical: allows them to stretch and contract
• Movement

Question 2

Cell shape aiding cell function: epithelial cells

Answer 2

• Flat and form continuous sheet covering surfaces
• Responsible for protection, absorption and secretion

Question 3

Nerve cell shape and function

Answer 3

• Responsible for transmitting electrical signals throughout NS
• Long and slender, allowing them to propagate over long distances

Question 4

Fat cell shape and function

Answer 4

• spherical
• used for energy storage
• Regulating body temp
• cushioning organs

Question 5

RBC shape and function

Answer 5

• Carries O from lungs to body
• Biconcave shape gives larger SA to carry more oxygen

Question 6

WBC shape and function

Answer 6

• round/irregular shape
• Fight infections and remove foreign invaders
• Pliable since they may need to squeeze through small spaces

Question 7

Epithelial cells as an example of shape relating to function

Answer 7

Question 8

Squamous Epithelium shape and function

Answer 8

Question 9

Columnar epithelium shape and function

Answer 9

Shape: tall and narrow. Oval shaped nuclei in basal region (attached to basement membrane)

Function: protection, absorption and movement

Question 10

Simple columnar epithelium

Answer 10

Single layer of columnar epithelial cells attached to the basement membrane. Two categories: ciliated and non-ciliated (glandular).

Question 11

Ciliated columnar epithelium

Answer 11

Many cilia on apical (top) surface to move mucus and other substances. Found in sperm ducts, lining the trachea, bronchi, kidney tubules, respiratory tract, and oviducts. Cilia function varies e.g.,
* Fallopian tubes - currents generated by the cilia propel the egg cell toward the uterus.
* Neuroepithelium of the ependyma that lines the ventricles of the brain and central canal
of the spinal cord - cilia move the cerebro-spinal fluid (CSF).

Question 12

Non ciliated columnar epithelium

Answer 12

Lining sections of the gastrointestinal tract (inner lining of oesophagus, stomach) and may have microvilli which increase the surface area for absorption.

Question 13

Stratified columnar epithelium

Answer 13

composed of column-shaped cells arranged in multiple layers.
* Function in secretion and protection.
* Found in the conjunctiva, pharynx, anus, male urethra and vas deferens, and
the excretory duct of mammary gland and major salivary glands.

Question 14

Pseudostratified columnar epithelium

Answer 14

Made up of a single layer of epithelial cells of different heights has its cell nuclei positioned in a manner suggestive of stratified epithelia. Have stereocilia.
* Helps in the secretion of mucus, and protection of the respiratory tract and the inner ear from the foreign particles, absorption of the excess fluid, and the transport of the substances e.g., enzymes and hormones.

Question 15

Cubical epithelium shape and function

Answer 15

Question 16

What is cell polarity?

Answer 16

asymmetric distribution of proteins at cells surface (also surface projections, organelles and cytoskeleton)

Question 17

How does polarity affect shape and function

Answer 17

• Morphology of cells and the location of membrane proteins of cells are optimised to fulfill their function
• Cells that create compartments must be polarized to maintain contents in their corresponding partitions
• Examples include epithelial cells (apical and basolateral surfaces), neuronal cells, migrating cells, and many immune cells require polarization to function

Question 18

Cell-cell and cell-ecm recognition

Answer 18

Some glycoproteins serve as identification tags that are specifically recognised by membrane proteins of other cells
* Carbohydrate groups are particularly important

Question 19

Attachment to cytoskeleton and ECM

Answer 19

INSIDE CELL
- microfilaments, actin, cytoskeleton
- Connecting inside to outside

OUTSIDE CELL
- ECM proteins (colleagen, elastin, laminin, fibronectin, proteoglycans)

PROTEINS (or complexes) THAT PASS THROUGH MEMBRANE
- maintain cell shape, motility, co-ordination of intracellular and extracellular changes

Question 20

How to attachments of cell-cell adhesions to cytoskeleton protect cell from mechanical stress

Answer 20

Surface adhesion proteins link to the cytoskeleton inside the cell
* Mechanical stresses are transmitted from cell to cell by cytoskeletal filaments anchored to cell- matrix and cell-cell adhesion sites – functions to protect cells from mechanical stress.