Alimentary Canal

Question 1

Functions of digestive system

Answer 1

• Digestion
• Secretion
• Absorption
• Motility

Question 2

3 pairs of salivary glands

Answer 2

1) sublingual
2) submandibular
3) parotid

Question 3

Large intestine is made up of:

Answer 3

• colon
• caecum
• rectum

Question 4

Mouth

Answer 4

Foodstuffs broken down by chewing; saliva added as lubricant

Question 5

Oesophagus

Answer 5

connects mouth to stomach

Question 6

Stomach

Answer 6

protein digested, food turned to liquid, storage and sterilisation (has HCL for protein digestion and sterilisation)

Question 7

Pancreas

Answer 7

Digestive enzymes for digestion of fats, carbohydrates & proteins

Question 8

Liver

Answer 8

Bile salts for digestion/absorption of fats in small intestine

Question 9

Gallbladder

Answer 9

stores and concentrates bile (underneath liver)

Question 10

Small intestine

Answer 10

Final stages of chemical digestion & nutrient absorption

Question 11

Large intestine

Answer 11

Water & salt absorption, bacterial colonisation, forms faeces (removing water to solidify faeces)

Question 12

Structure of alimentary canal:

Answer 12

Continuous hollow tube (varying diameter)
Oesophagus  rectum (~ 8 metres long)
Tube wall has same structural organisation throughout length

Question 13

Four distinctive layers (tunics)

Answer 13

Mucosa (epithelium, lamina propria(loose connective tissue), muscularis mocusae(thin layer of smooth muscle))
Submucosa (thicker) (connective tissue, vessels, nerves)
Muscularis externa (muscle) (circular muscle layer on inside and longitudinal layer on outside)
Serosa (inside peritoneum cavity)/adventitia (outside peritoneum cavity)(connective tissue)

Question 14

Structure of alimentary canal

Answer 14

• Continuous hollow tube
• 8m long (oesophagus to rectum)
• Tube wall has same structural organisation throughout length

Question 15

Blood Bessel plexus

Answer 15

• Between submucosa & circular muscalaris layer (submucosal plexus)
• Between circular & longitudinal muscle layer (of muscular) (myenteric plexus)

Question 16

Gut

Answer 16

Has a lot of neutrons that give it a brain of its own

Question 17

Enteric Nervous System consists of

Answer 17

Submucosal & myenteric system (controls whole gut)

Question 18

Stratified Squamous Epithelium in

Answer 18

Mouth, oesophagus, anal canal

Question 19

Simple columnar epithelium

Answer 19

Stomach, small & large intestine

Question 20

Epithelium makes & secretes:

Answer 20

Enzymes, hormones & mucos

Question 21

What is lamina propia?

Answer 21

Loose connective tissue (glands, blood/lymph vessels)

Question 22

What is muscular mucosae?

Answer 22

Thin smooth muscle layer

Question 23

Submucosa

Answer 23

• Thick irregular connective tissue for support
• Has neurons & vessels
• Submucosal (Meissner´s) plexus (parasympathetic/rest & digest) (between submucosa & muscular layer)
• Submucosal glands in oesophagus (lubricant) & duodenum (start of intestine)(carbonates to neutralise acid from stomach)

Question 24

Serosa/Adventitia

Answer 24

Connective tissue outer layer of alimentary canal

Question 25

Outside peritoneal cavity, Adventitia attaches

Answer 25

oesophagus and rectum to surrounding structures

Question 26

Inside peritoneal cavity Serusa surrounds:

Answer 26

Stomach, small intestine and large intestine

Question 27

Muscular Externa consists of 2 concentric thick layers of smooth muscle

Answer 27

1) Inner layers = circular muscle | 2) Outer layer = longitudinal muscle (shortens tube)

Question 28

Muscle contraction for motility/movement =>

Answer 28

peristalsis, segmentation

Question 29

Submucosal + myenteric plexuses =

Answer 29

enteric nervous system (ENS) --> independent control of gut function

Question 30

Autonomic control

Answer 30

Long (parasympathetic) and short (ENS) reflexes

Question 31

Parasympathetic => vagus nerve

Answer 31

stimulates secretion & motility

Question 32

Sympathetic => splanchnic nerve

Answer 32

Inhibits secretion & motility doesn't affect salivation

Question 33

Arterial supply:

Answer 33

Descending aorta has 3 branches that supply different segments of the alimentary canal

Question 34

Celiac trunk:

Answer 34

stomach, upper small intestine (duodenum), pancreas, liver

Question 35

Superior mesenteric artery:

Answer 35

Lower small intestine, caecum, ascending & transverse colon

Question 36

Inferior mesenteric artery:

Answer 36

Descending and sigmoid colon, rectum

Question 37

Venous drainage

Answer 37

Stomach drains: gastric veins Pancreas drains: splenic vein Small intestine, caecum, ascending & transverse colon: superior mesenteric vein Descending & sigmoid colon, rectum: inferior mesenteric vein All drain into hepatic portal vein (into liver), to hepatic vein

Question 38

Hepatic portal control

Answer 38

- Hepatic artery brings oxygenated blood to liver - Hepatic portal vein brings deoxygenated blood from GI tract to liver for cleaning - Hepatic vein then drains the blood from liver back to inferior vena cava