organisation of cells

Question 1

what are the 3 major salivary glands?

Answer 1

• submandibular (equal ish serous & mucous secreting)
• parotid (more serous & less mucous secreting)
• sublingual (more muscous & less serous secreting)

*there are other smaller ones scattered in oral mucosa

Question 2

what is an unusual feature of salivatory glands?

Answer 2

straited ducts - most ducts just convey secretory product but straited ducts MODIFY the saliva that is passing through them by pumping salt out the fluid so our saliva is hypotonic to blood (lower salt conc)

Question 3

what are the layers of digestive tract?

Answer 3

1. muscosa: 3 parts = epithelium (sits on basal lamina), lamina propria (loose connective tissue), muscularis mucosae (thin layer smooth muscle)
2. submucosa= loose connective tissue
3. muscularis externa = 2 thick layers of smooth muscle, inner circular layer & outer longitudinal layer
4. serosa or adventitia = outer layer of connective tissue that either suspends sigestive tract or attaches to other organs

Question 4

what are the various types of mucosa?

Answer 4

protective = non keratinized, stratified, squamous epithelium

absorptive = simple columnar epithelium with villi & tubular glands

secretary = simple columnar epithelium with extensive tubular glands

protective & absorptive = simple columnar epithelium & tubular glands

Question 5

what type of mucosa is:
a) large intestine
b) stomach
c) small intestine
d) oral cavity, pharynx, oesophagus, anal canal

Answer 5

a) protective & absorptive
b) secretory
c) absorptive
d) protective

Question 6

what is enteric nervous system?

Answer 6

nervous system of digestive tract - same number of neurons as spinal cord
- it receives info from autonomic nervous system but is capable of coordinating gut motility locally
- most neurons live in groups called ganglia between 2 muscle layers that make up muscularis externa

Question 7

how does respiratory system deal with particles coming into airway?

Answer 7

goblet cells (from epithelium) together with submucosal glands produce a viscous fluid that coats surface of airway, trapping particles that are propelled out airway by cilia

Question 8

bronchi Vs bronchioles?

Answer 8

bronchi = larger diameter and made of hyaline cartilage

bronchioles are next in resp tree = smaller diameter, no cartilage and smooth muscle perdominates their wall

Question 9

what is alveoli composed of?

Answer 9

lined by sqaumous cells

Question 10

what is composition of trachea from airway out?

Answer 10

airway then respiratory epithelium then lamina propria (thick layer) then hyaline cartilage/tracheal ring

Question 11

does gas exchange occur across epithelia?

Answer 11

NO = columnar cells get shorter further down respiratory tree you go

Question 12

what is structure of liver?

Answer 12

made of large lobules each with similair hexagonal arrangement

Question 13

how is blood delivered to liver lobule?

Answer 13

at each corner of lobule there is branch of hepatic portal vein and hepatic artery and bile duct

gets to centre by passing through hepatic sinusoids past sheets of liver called hepatocytes to central vein, terminla hepatic venule that drains to haptic veins

Question 14

what is portal triad?

Answer 14

the branch of hepatic portal vein, hepatic artery and bile duct at each lobule corner

Question 15

what is unusual about pancreas?

Answer 15

it’s both exocrine & endocrine

Question 16

how is pancreas exocrine?

Answer 16

it produces about a litre a day of digestive juices containing:
-proteases to break down proteins
- lipases to break down lipids
- nucleases to break donw DNA/RNA
= these enter duodenum (which absorbs vitamins, minerals & nutrients) via pancreatic duct

Question 17

how is pancreas endocrine?

Answer 17

consists of small scattered islands of tissues called islets of langerhans = groups of pancreatic cells that secrete insulin & glucagon
(islets scattered so only occupy a small volume)