Digestive System Flashcards
digestion
The breaking down of larger food particles into small molecules ready to enter the body cells
absorption
The passage of smaller molecules into blood and lymph
digestive system
the group of organs that break down food in order to absorb its nutrients
ingestion
taking food into the mouth
secretion
a process by which substances are produced and discharged from a cell, gland, or organ
defecation
the elimination of variable amounts of indigestible substances from the GI tract through the anus
mixing and propulsion
alternating contraction and relaxation of smooth muscle in the walls of the GI tract to mix food and secretions and propel them toward the anus for defecation
functions of digestive system 6
ingestion secretion defecation mixing and propulsion mechanical digestion chemical digestion
mastication
the process in which food is crushed and mixed with saliva to form a bolus for swallowing
bolus
a ball-like mixture of food and saliva that forms in the mouth during the process of chewing
4 layers of digestive tract
mucosa
submucosa
muscularis
serosa
mucosa
inner mucous membrane
submucosa
loose connective tissue containing nerves, blood, and lymphatic vessels
muscularis
smooth muscle
peritoneum
the serous membrane lining the cavity of the abdomen and covering the abdominal organs.
x2 types of peritoneum
parietal + visceral
3 pairs of salivary glands
Parotid
Submandibular
Sublingual
3 stages of swallowing
voluntary
pharyngeal
oesophageal
voluntary stage (swallowing)
bolus moves to oropharynx
pharyngeal stage (swallowing)
the involuntary passage of the bolus through the pharynx into the oesophagus, breathing is temporarily interrupted
oesophageal stage (swallowing)
the involuntary passage of the bolus through the oesophagus into the stomach
deglutition centre
located in the medulla oblongata and inferior pons, is responsible for swallowing.
oesophagus
A muscular, collapsible tube that lies posterior to the trachea, it is continuous with the laryngopharynx above, it joins the stomach just below the diaphragm
oesophagus function
creates mucous and transports food to the stomach
x2 two oesophagus sphincters
upper
lower
Upper Oesophageal Sphincter function
Regulates the passage of food from the laryngopharynx into the oesophagus
Lower Oesophageal Sphincter function
when closed, prevents backflow of acid and stomach contents from travelling backwards from the stomach
stomach function
mixing area and reservoir for food, slowly releases material into the duodenum, converts bolus to chyme, mechanically digests food via churning
4 sections of stomach
cardia (opening to stomach at top)
fundus (rounded top portion)
body (large central portion)
pylorus (connects to the duodenum)
sphincter in stomach
pyloric sphincter
rugae
Rugae - the large folds of mucosa tissue lining the inside of the stomach
These Rugae are lined with narrow channels called gastric pits and columns of secretory cells called gastric glands
gastric juice function
pepsin (the chief protein digestant) allows for chemical digestion and HCI allows non specific defence against microbes
pepsin
enzyme that helps digestion of protein
small intestine function
greatest amount of digestion and absorption
The small intestine has villi and microvilli to increase the surface area for effective and maximised absorption. This increases the rate of nutrient absorption/diffusion
small intestine x3 sections
DUODENUM, JEJENUM, ILIUM
large intestine function
to absorb water and salts from the material that has not been digested as food
large intestine x4 sections
COLON, CAECUM, RECTUM, ANUS
appendix (+function)
The appendix is a narrow, finger-shaped pouch that projects out from the colon
It is believed to have lymphatic properties due to the abundance of lymph nodes situated around it.
4 sections of colon
The Ascending Colon
The Transverse Colon
The Descending Colon
The Sigmoid Colon
rectum
a straight muscular tube that begins at the termination of the sigmoid colon and ends at the anal canal
rectum function
receives stool from the colon
anal canal function
the maintenance of faecal continence and defecation
this is achieved with the help of the anal sphincters and the neighbouring puborectalis muscle.
2 anal sphincters
The superior end of the anal canal is the internal anal sphincter
The inferior end is the external anal sphincter
gastroenterology
the branch of medicine that looks at diseases of the oesophagus (gullet), stomach, small and large intestines (bowel), liver, gallbladder and pancreas
liver location
The upper right quadrant of the abdomen
liver function
filtration and storage of blood, metabolism (carbs/proteins/fats) and detoxification (drugs/poisons), secretory (bile), synthesis (plasma proteins)
2 major lobes of liver
right anterior/left anterior
2 minor lobes of liver
caudate posterior/quadrate posterior
blood supply for the liver?
2 vessels
Hepatic artery + Hepatic portal Vein (from GI tract tissues)
lobule
The hepatic lobules are small divisions of the liver. Each lobule has a central branch of the hepatic vein, with its tributary sinusoids.
sinusoids
microscopic vessels within the liver, lined with phagocytic cells
hepatocytes
functional cells of the liver, responsible for metabolic, endocrine, and secretory function. Hepatocytes are arranged in sheets called hepatic laminae.
bile canaliculi
mini tubules that receive bile secreted by hepatocytes
the gall bladder
a sac-like structure inferior to the liver. It is responsible for storing bile produced by the liver
bile
A fluid produced by the liver and stored in the gallbladder. It helps with the digestion of fats by emulsifying fats into fatty acids, which can then be absorbed.
pancreas
a retroperitoneal gland, posterior to the greater curvature of the stomach. It is divided 3 sections, the head, body, and tail.
pancreas function
x2 primary functions
endocrine (blood sugar regulation) - islets of langerhans secrete insulin and glucagon into the bloodstream
exocrine (digestive enzymes) - proteases (proteins) (chymotrypsin + trypsin, amylase (carbs), lipase (fats)
pancreatic juice consists of
digestive enzymes + bicarbonate
bicarbonate
a base used for neutralising the acid entering the small intestine from the stomach
GI bleed
Any form of bleeding in the gastrointestinal tract from the mouth to the rectum.
clinical presentation of GI bleed
3
Vomiting of blood black or red
Bloody stool
Black stool
sites of lower GI bleed
+ their causes
(3)
Jejunum (polyps (tissue growths, clumps of cells), cancer, IBS)
Ileum (polyps (tissue growths, clumps of cells), cancer, IBS)
Colon (polyps (tissue growths, clumps of cells), cancer, IBS)
sites of upper GI bleed
+ their causes
(3)
Oesophagus (varices, enlarged/swollen veins)
Stomach (ulcer (sore), gastritis (inflammation of the stomach lining))
Duodenum (duodenal ulcers)
appendicitis
A painful inflammation of the appendix
appendicitis clinical presentation
3
Pain in the lower right iliac abdominal region
Progressive over 4-6 hours
Rebound pain
appendicitis cautions
sudden pain relief may indicate rupture of appendix, this leads to peritonitis
peritonitis
Inflammation of the peritoneum
peritonitis clinical presentation
4
Board-like abdomen
Distension (dilation/ballooning effect) and rigid abdomen
Fever
Nausea and Vomiting
peritonitis potential causes
Abdominal Surgery (infection risk)
Ectopic Pregnancy
Perforation (ulcer, trauma, appendix rupture
bowel obstructions
A partial or complete block of the small or large intestine that keeps food, liquid, gas, and stool from moving through the intestines in a normal way.
intussusception
A serious medical condition where part of the intestine slips (telescopes, see picture ->) into a neighbouring part resulting in blockage of food and/or fluid from passing through and loss of
blood supply to the affected part of the intestine.
paralytic ileus
A condition where the motor activity of the bowel is impaired, usually without the presence of a physical obstruction.
retroperistalsis
The reverse of the involuntary smooth muscle contractions of peristalsis
dysentery
An infection of the intestines that causes diarrhoea containing blood or mucus
