anatomy

Question 1

function of digestive system

Answer 1

2 roles: Digestion – function is to process food! Absorption – transfer of nutrients to circulation

Question 2

gastrointestinal tract histology- mucosa

Answer 2

• The mucosa or mucous membrane lines the cavities of the body and surface of internal organs.

Question 3

histology- laminate propria

Answer 3

-Lamina propria is a thin layer of loose connective tissue which lies beneath the epithelium. It contains inflammatory cells and provides support and nutrients to the overlying epithelium.

Question 4

histology- muscular mucosae

Answer 4

Muscularis mucosae is the next layer deep to the lamina propria and is composed of smooth muscle and is continuous all the way through the entire length of the gastrointestinal tract.

Question 5

histology- submucosa

Answer 5

Next is the submucosa which is deep to the muscularis mucosae. It is composed of dense irregular connective tissue and contains many blood vessels, nerves and also lymphatic vessels (which collects additional fluid aroud the body outside the vasculature).

Question 6

histology- muscular propria

Answer 6

-The muscularis propria is also called the muscularis externa and comprised of inner circular muscle and outer longitudinal muscle. This muscle is smooth muscle and is responsible for peristalsis – movement of food and products of digestion.

Question 7

histology- adventitia

Answer 7

-Adventitia is an outer layer of fibrous connective tissue surrounding an organ. In the gut, this would be at the oral cavity, upper end of the oesophagus in the chest, or thorax, and ascending and descending colon and rectum. A serosa would be that part of the tissue that is fixed, in other words the rest of the gastrointestinal tract. In addition, the serosa or serous membrane allows for reduction of friction.

Question 8

miessners and auerbachs plexus

Answer 8

• nerve plexuses
• miessenrs: located in submucosa
• auerbachs plexus- between musuclaris and adventitia

Question 9

brunners glands

Answer 9

secretes bicarbonate ions to neutralise the acid from the stomach
- found in submucosa

Question 10

Peyer’s patches

Answer 10

• lymphoid follicles and form part of the immune function preventing the growth of dangerous bacteria.
• found in mucosa

Question 11

oesophagus

Answer 11

Mucosa – stratified squamous (non-keratinising) epithelium (E), lamina propria, muscularis mucosae
Submucosa (SM) – glands (G) and lymphoid follicles (Ly)
Muscularis mucosae/externa (circular (CM) and longitudinal (LM)
Serosa

• upper 1/3: skeletal
• middle 1/3: mixed
• lower 1/3: smooth

Question 12

layout abdomen

Answer 12

1. R. hypochondrium
2. Epigastric
3. L. hypochondrium
4. R. lumbar
5. Umbilical
6. L. lumbar
7. R. iliac fossa
8. Suprapubic (hypogastrium)
9. L. iliac fossa

1 2 3
4. 5. 6
7. 8. 9

Question 13

stomach

Answer 13

Found in left hypochondrium/
epigastric region

Anterior / superior
- Lower ribs/diaphragm
- Liver

Posterior / inferior
- Diaphragm, spleen, kidney (L.), adrenal gland, pancreas

Greater omentum (fatty tissue) attaches to greater curvature.
Pyloric stenosis can affect the pyloric sphincter.
Presents with projectile vomiting, without bile (as that enters the duodenum)

Question 14

stomach histology

Answer 14

Stomach is a hollow muscular organ and is responsible for the breakdown of what is ingested by enzymes and hydrochloric acid.

It lies in the epigastrium and the left hypochondrium.

Question 15

rugae, stomach histology

Answer 15

Rugae – folds of the organ which can be seen with the naked eye. They help increase surface area and allow for the folding of the organ.

Question 16

3 layers of stomach wall

Answer 16

muscular propria/muscularis external
- These three layers of muscle help with the churning, or mixing, of the stomach contents called the chyme: usual inner circular and outer longitudinal, but also an extra layer called the innermost oblique.

Question 17

endocrine cells

Answer 17

Endocrine cells produce gastrin

This stimulates the parietal cells to produce hydrochloric acid

The hydrochloric acid then breaks down pepsinogen to become pepsin produced from the chief cells.

Mucous and surface mucous cells protect the mucosa

Question 18

small intestines

Answer 18

• simple columnar
• have finger like projections and are well designed to increase surface area, and therefore aid in the digestion and absorption which typically happens in the small intestine, namely the duodenum, jejunum and ileum.

Question 19

duodenum

Answer 19

Receives chyme
Contains Brunner’s glands:
- alkaline secretion
Receives common bile duct
(Sphincter of Oddi)
- Major duodenal papilla
- Bile
- Pancreatic “juice”
Ends at duodenojejunal junction

Question 20

serosa

Answer 20

• 2 layers of mesothelium

Question 21

pancreas

Answer 21

functions: hormonal ( where the secretions pass to the blood stream), digestive (exocrine)

endocrine portion- islets of langerhans

Question 22

insulin, endocrine

Answer 22

Insulin – promotes glucose absorption from blood into liver, skeletal muscle and fat cells. This enables the conversion to glycogen - i.e. storage of glucose in this form.

Question 23

glucagon, endocrine

Answer 23

-this does the opposite and results in the conversion of the stored glycogen into glucose for release into the bloodstream when levels are low.

Question 24

somatostatin, endocrine

Answer 24

this helps to reduce acid secretion and helps to slow down the digestive process, although it has a variety of other functions in the body.

Question 25

exocrine gland

Answer 25

These digestive enzymes help break down carbohydrates, proteins and fats. - bicarbonate ions

Question 26

liver

Answer 26

The liver lies in the upper quadrant of the abdomen, extending over to the left. Specifically it lies in the right hypochondrium, extending to the epigastric region and then to the left hypochondrium. It is the largest gland of the body and heaviest of our internal organs.

Question 27

large intestine/colon

Answer 27

The colon is the distal part of the GI tract and extends from the caecum at the right iliac fossa to the anal canal.

Question 28

caecum

Answer 28

The caecum is the most proximal part of the large intestine and is located between the ileum (distal small intestine) and the ascending colon. It simply acts as a reservoir for chyme which it receives from the ileum. - can be found in the right iliac fossa of the abdomen. It lies inferiorly to the ileocecal junction and can be palpated if enlarged due to faeces, inflammation or malignancy.

Question 29

ileocacaecal valve

Answer 29

Between the caecum and ilium is the ileocaecal valve. This structure prevents reflux of large bowel contents into the ileum during peristalsis and is thought to function passively.

Question 30

colon

Answer 30

The colon can be divided into four parts – ascending, transverse, descending and sigmoid. These sections form an arch, which encircles the small intestine and is approx. 150cm long.

Question 31

taenia coli

Answer 31

3 longitudinal bands of smooth muscle on the outside of the ascending, transverse and descending colon.

Question 32

haustra

Answer 32

Circumferential contraction of the inner muscular layer of the colon

Question 33

appendice epiploicae

Answer 33

Pouches of peritoneum filled with fat mainly on the transverse and sigmoid colon, though not the rectum.

Question 34

goblet cells

Answer 34

Goblet cells – produce mucous as the role of the large intestine is to absorb fluid from the GI tract

Question 35

blood supply for GI tract

Answer 35

Foregut – supplies the oesophagus (lower portion), stomach, liver, spleen and first half of the duodenum Midgut – supplies the last half of the duodenum, jejunum, ileum, caecum, appendix, ascending colon and first half to first 2/3 of the transverse colon. Hindgut – last 1/3 of the transverse colon, descending colon, sigmoid colon and rectum.

Question 36

venous drainage of GI tract

Answer 36

Portal venous drainage is for the unpaired abdominal organs i.e. the gut and spleen. Femoral veins drain the lower limb Internal iliac veins drain the pelvis Renal veins drain the kidneys Hepatci vein is the main vein draining the liver