7. Glands 2

Question 1

What is a gland?

Answer 1

An epithelial cell or collection of cells specialised for secretion; secretion into the bloodstream or onto an epithelial surface.

Question 2

What is an adenocarcinoma?

Answer 2

Malignant growth derived from glandular cells of epithelial origin.

Question 3

What are some important types of unicellular glands?

Answer 3

Those important for producing mucus in the respiratory and intestinal tracts.

Question 4

What are the parotid glands?

Answer 4

Bilateral, major salivary gland, side of mouth and in front of years
Serous acini only, contains amylase
Enclosed in tough fibrous capsule

Question 5

What is the function of the parotid glands?

Answer 5

To secrete a serous secretion that contains enzymes that digest food, lubricates bolus during swallowing.

Question 6

Why is parotitis painful?

Answer 6

Because the parotid glands are enclosed in the tough fibrous capsule it limits its swelling.

Question 7

Activation of what part of the nervous system increases saliva production?

Answer 7

Parasympathetic system

Question 8

Describe the surface anatomy of the parotid glands

Answer 8

Head of mandible at top by ear and cheek bone
Mastoid process by ear lobe
Middle and lower of mandile by jaw

Question 9

What kind of ducts do the parotid glands contain?

Answer 9

Striated ducts

Question 10

What are the submandibular glands?

Answer 10

Salivary glands below parotid glands

Separated by mylohyoid muscle

Question 11

What is the stimulus for salivary gland secretion?

Answer 11

Neuronal, both parasympathetic and sympathetic
Parasympathetic produces a large volume of watery saliva rich in enzymes.
Sympathetic produces small, thick secretion of saliva rich in mucus.

Question 12

What is the largest exocrine gland?

Answer 12

The liver, separated into two lobes with the left that can regenerate

Question 13

What is the hepatic blood supply?

Answer 13

Hepatic portal vien carries deoxygenated blood from the spleen, stomach and intestines to the liver.
Hepatic artery carries oxygenated blood from the aorta to the liver.
Hepatic artery and portal vein come together within a triad in sinusoids to central canal.

Question 14

What is the structure of the sinusoid?

Answer 14

Incomplete basement membrane and intercellular gaps.

Passes material quickly between gaps within endothelial cells and basement membrane.

Question 15

Is a hepatocyte multicellular?

Answer 15

It is either bi or tri nucleated.

As liver is main factory, need a lot of enzymes.

Question 16

Describe the structure of the portal triad.

Answer 16

Hepatic portal vein and artery rejoin and flow back to central canal. Bile flows in opposite direction to bile duct.
Blood flows through sinusoid, Kupffer cells in lumen.
Space of disse either side of sinusoid contains dendritic cells and stellate cells. The hepatocytes either side with bile canaliculus. Bile duct is underneath not in between hepatocytes, canaliculi inbetween connects to main duct.

Question 17

What are kupffer cells?

Answer 17

Specialist macrophages that form part of sinusoidal lining
Constitute 80% of tissue macrophages in the body
Exposed to gut derived bacteira, microbial and cell debris
They trap and phagocytose aged erythrocytes missed by the spleen, can take over after splenectomy
Perforations allow Kupffer cells to migrate into liver tissue

Question 18

What are stellate/ito cells?

Answer 18

Cells full of cytoplasmic vacuoles containing Vitamin A.
In cirrhosis, lose storage capability and differentiate into myofibroblasts, synthesis and deposit collagen.
Results in liver fibrosis.

Question 19

What are the functions of the liver?

Answer 19

Storage of iron, Vitamins A B D K, glycogen and copper
Anabolism (production) of proteins, albumin, enzymes, haemopoeisus in foetus from weeks 5-32.
Catabolism of drugs, hormones, haemoglobin, toxins
Bile production, filtering cell debris, hormone modification

Question 20

Describe the structure of hepatocytes

Answer 20

80% of liver cell population, very regenerative
Many mitochondria, lots of peroxisomes, free ribosomes, RER, SER, GA, many glycogen deposits
This same cell exectures both endocrine and exocrine functions; exocrine secreting bile, endocrine secreting IGF 1 and albumin.

Question 21

What signalling can occur in the liver?

Answer 21

Autocrine signalling - vascular endothelial growth factor, stimulates formation of blood vessels.
Paracrine signalling - succinate - hepatocyte regeneration
Endocrine signalling - GH to IGF1, can act on self and bone
Intracrine signalling - oestrogen and thyroid hormones stimulate apolipoprotein A1 production increasing HDL in blood reducing risk of infection and myocardial infarction.