Digestive System (anatomy)

Question 1

What is the purpose of the gut

Answer 1

Break food down
Until it is small enough to be absorbed through the gut wall into blood/lymph
Energy/nutrients can then be utilised
Get rid of what we don’t need
Plus - absorb water, excrete cholesterol and synthesise some vitamins

Question 2

Describe the gastrointestinal system

Answer 2

Is a tube and supporting organs: salivary glands, liver and pancreas

Question 3

Describe the peritoneum

Answer 3

Is a serous membrane sac in the abdomen
It encases the abdominal organs to:
Provide structure and hold organs in place
Contain any developing infections to stop them spreading
Reduces friction: the two layers (parietal and visceral) have serous fluid between them, making them slippery: friction is bad because it causes inflammation

Question 4

Describe the motility of the gut

Answer 4

Peristalsis ( move forward)
Segmentation ( back and forth mixes )
Mass movements ( rapid movement forward)

Question 5

What is the function of the mouth

Answer 5

Mastication ( chewing )
Hard palate made of bone ( anterior)
Soft palate made of muscle ( posterior)
Initial digestive enzymes released
Infection control

Question 6

What is the pharynx ( throat )

Answer 6

3 sections = naso-, oro-, laryngo- pharynx
Food goes from oral cavity to oesophagus via the pharynx

Question 7

What is the oesophagus

Answer 7

Rapid transport of bolus to stomach through thorax
25cm long tube from pharynx to stomach

Question 8

What are sphincters

Answer 8

Thickened rings of circular muscle
Keep GI tract a one way system to prevent backflow

Question 9

Describe the function of tongue

Answer 9

Voluntary muscle covered by mucous membrane, needed for deglutition ( swallowing)
Anchored to floor of mouth by the frenulum
Covered in papillae which contains taste buds

Question 10

Describe the salivary glands

Answer 10

Three main pairs
Parotid
Submandibular
Sub-lingual

Question 11

What is the role of saliva

Answer 11

Release digestive enzymes e.g. amylase to break down complex sugars
Oral hygiene- prevents tooth decay, anti microbial antibodies
Lubricate food bolus

Question 12

What is the function of the stomach

Answer 12

To produce chyme - bolus and gastric juice
( physical and chemical breakdown, digestion started and storage)
Muscle layers - three layers help to churn food
Mucous membrane - thrown in rugae enabling it to stretch when full, gastric glands release the constituents of gastric juice

Question 13

What is the function of gastric juice

Answer 13

Unravels proteins
Activates enzymes: pepsinogen to pepsin
Disinfects stomach contents

Question 14

What is the function of chyme

Answer 14

Partially digested
Acidic
Very concentrated

Question 15

What is the function of the duodenum

Answer 15

Start of small intestine
C- shaped curve around the pancreas
Pancreas and liver join gut tube here
Acidic chyme is neutralised here
Water enters duodenum through gut walls ( dilutes chyme)
Digestive enzymes enter here

Question 16

What is the function of the liver

Answer 16

Mainly composed of cells called hepatocytes
Produces bile
Synthesises proteins like albumin
Detoxifies blood
Energy storage ( glycogen)

Question 17

What is the function of the gallbladder

Answer 17

Connected to liver above and duodenum below
Stores and concentrates bile
Connects to GI tract through a system of tubes (biliary tree)
Contracts when fat is detected in the duodenum ( release bile into duodenum)

Question 18

What is the function of bile

Answer 18

Contains bile salts ( help emulsify fats into smaller droplets, makes it possible to absorb cholesterol and fatty acids and fat soluble vitamins)
Contains bilirubin
When RBCS die bilirubin is released and needs to be extracted from body ( gives stol colour)

Question 19

What is the function of the pancreas

Answer 19

Endocrine function- produces insulin/ glucagon
Exocrine function- produces pancreatic juice ( contains active enzymes for digestion e.g amylase, and inactive enzymes e.g trypsinogen

Question 20

What is the function of jejunum and ileum

Answer 20

Jejunum - next section of small intestine following from the duodenum, middle section is 2 meters long
Ileum - last section of small intestine is 3 meters long
Secretes alkaline intestinal juice, final digestion, nutrient absorption ( mainly jejunum), water/ electrolyte absorption ( mainly ileum)

Question 21

What is the structure of small intestine

Answer 21

Mucous membrane needs high SA
Has pilcae which don’t smooth out
Has villi - 1mm long projections, covered by enterocytes, cells which complete the chemical digestion
Enterocytes have microvilli- even smaller projections to increase nutrient absorption

Question 22

Describe the function of large intestine

Answer 22

Made up of caecum, colon ( ascending, transverse, descending, sigmoid), rectum, and anal canal
General role - final water and electrolyte absorption, temporary storage and secretes mucus to lubricate food waste moving along
Caecum - wide pouch that acts as a reservoir, once full food moves the large intestine
Rectum/anus - defaecation

Question 23

Describe gut microbiota/ microbiome

Answer 23

Essentially refers to the bacteria/fungi/viruses that live in our gut ( produce some vitamins, prevent other bacteria from causing disease)
Plays a big role in health and disease

Question 24

What is egestion

Answer 24

We have to get rid of unabsorbed materials, these pass through the colon, which absorbs the most of the remaining fluid from the material
Faeces is temporarily stored in colon and the 1-2 times/day moved into rectum, rectum normally empty, when it fills the stretch of the rectum alerts us to the need to defaecate
Anus- has two sphincters - internal ( involuntary)and external ( voluntary)