C1 Tissues and Cells

Question 1

What do parietal cells do?

Answer 1

Secrete acid

Question 2

What do G cells do?

Answer 2

Secrete gastrin

Question 3

What do epithelial cells do?

Answer 3

Separate one compartment from another, may be specialised for secretion.

Question 4

What does connective tissue do?

Answer 4

Structural role, main types of cells are fibroblasts. Fatty connective (adipose) tissue, blood vessels.

Question 5

What does nervous tissue do?

Answer 5

Sensory and motor signals.

Question 6

What does muscle tissue do?

Answer 6

Role in support and movement.

Question 7

What is basement membrane?

Answer 7

Mesh-like fibrous protein, anchors epithelial and endothelial cells to connective tissue.
Barrier of particles and macromolecules

Question 8

What is hyaluronan? (Extracellular matrix)

Answer 8

Glycan (polysaccharide). Medical use = osteoarthritis and subcutaneous injections.

Question 9

What is collagen? (Extracellular matrix)

Answer 9

Most abundant protein in the body, triple helix.. Medical use = cosmetic and reconstructive surgery.

Question 10

What are the three types of epithelial cells? Examples?

Answer 10

1. Simple epithelium (single layer) e.g. stomach and intestine.
2. Stratified epithelium (multiple layers of cells) can be keratinised e.g. skin or non-keratinised e.g. oesophagus and inside mouth.
3. Specialised epithelial cells (secretion) e.g. goblet cells, (microvilli) e.g. enterocyte, (cillia) e.g. lung epithelium.

Question 11

Describe the gastric pit

Answer 11

Mucus layer- glycosylated proteins protective gel layer with neutral pH
Mucous cell/Neck cell - produce mucus and line most of the surface in the stomach
Parietal cell - produce gastric acid
Other cell types e.g. G cells produce gastrin and Chief cells produce pepsin
Connective tissue - fibroblast cells, blood vessels.

Question 12

What is the basolateral membrane?

Answer 12

Faces the epithelial cells/supporting tissue

Question 13

What is the apical membrane?

Answer 13

Faces the lumen

Question 14

What are the three types of junction between cells?

Answer 14

1. Tight junction prevents passage of small molecules and fluid between cells
2. Anchoring junctions linked to cytoskeletal structures and provide rigidity in a group of cells
3. Gap junctions provide channels between cells thereby facilitating movement of small molecules between neighbouring cells.

Question 15

What is mucus?

Answer 15

Network of proteins with sugar polymers attached. Formation of a viscous layer (gel) due to sugar chains retaining water.
Secretion of HCO3-
Maintains a neutral environment at cell surface.

Question 16

What is glycosylation?

Answer 16

Post-translational modification of amino acid chain with sugar moieties

Question 17

What are the two types of glycosylation and where do they take place?

Answer 17

N-glycosylation in the endoplasmic reticulum
N-acetylglucosamine linked to asparagine
O-glycosylation in the golgi complex
N-acetylglucosamine linked to serine

Question 18

What are the three important roles of glycosylation?

Answer 18

1. secreted proteins e.g. components of gastric mucus
2. blood type antigens
3. immunity (transplant rejection)

Question 19

What are the four steps to protein sorting?

Answer 19

1. Synthesis/translation in rough ER (N-linked glycosylation)
2. Vesicle transport form rough ER to golgi complex (O-linked glycosylation)
3. Transport vesicles move to membrane
4. Membrane fusion a. delivery of membrane bound proteins to surface, b. secretion of extracellular proteins

Question 20

What are the features of an active parietal cell?

Answer 20

Large surface area to volume ratio
Small number of internal vesicles
Proton pump on apical surface

Question 21

What are the features of an inactive parietal cell?

Answer 21

(resting)
Small surface area to volume ratio
Large number of internal vesicles (tubulovesicles)
Proton pump internalised

Question 22

What causes gastric ulceration? (Final diagram)

Answer 22

Cell and tissue dammage –> Histamine released by Mast Cell ; signalling, immune cells invade area and cause swelling.
Increased blood flow causes redness and bleeding
Loss of protective function and pain caused