digestive system Flashcards
(25 cards)
overview of abdomen
The anatomical location for the abdomen is from the diaphragm to the pelvic inlet/ lower limbs
It is enclosed by the abdominal wall and the inner large peritoneal cavity
Functions of the abdominal cavity
. breathing = The abdominal wall relaxes to allow the thoracic cavity to expand and contracts to reduce the thoracic cavity (forcibly when coughing or sneezing)
. It contains and protects the major organs
. Increasing abdominal pressure = contraction of the abdominal wall assists in mictuation defecation and childbirth
Peritoneum
• This is the innermost layer of the abdominal wall
• It is a closed sac for men, unclosed in women (there is an opening for the uterine tubes)
It is a
• Continuous serous membrane
• Layer of simple squamous epithelium
• Supported by connective tissues
There are 2 layers names by its role / location
• Parietal – lines the abdominal wall / peritoneal cavity
• Visceral (serosal) – covering the organs
Peritoneal cavity
• The cavity only contains minimal serous fluid – 5-20ml
• Fluid has an important role in peritoneal homeostasis
• It is divided into 2 parts
greater sac - most of the space
lesser sac - smaller area
omenta
2 layers which connect the stomach / first part of the duodenum to the other organs
Mesenteries
Surround and support loops of bowel, connecting to the posterior abdominal wall
It allows for some movement of bowel
The digestive system
• It converts food into energy and absorbs nutrients
main processes =
ingestion
propulsion
digestion (mechanical and chemical)
absorption
elimination
Nerve supply of the GI tract
• There is intrinsic and extrinsic innervation
• All of the digestive system is innervated by the autonomic nervous system
Parasympathetic
• Increases secretions and motility
• Mostly the vagus nerve and sacral nerve
Sympathetic
• Decreases secretions and motility
• This is your spinal nerves along the spine
What is the aim of digestion?
• To break down food in preparation for absorption
It is mechanical
• There is movement along the GI tract
• Breaking down the food increases the surface area for absorption
• As the food passes through it mixes with chemicals / secretions
Chemical enzymes
• Amylase – carbohydrates (salivary glands and
pancreas)
• Proteases (pancreas) and hydrochloric acid (stomach) – proteins
• Bile (pancreas) and lipases (pancreas)- fats
tongue
main functions
- mastication
- swallowing
- speech
The role of the tongue in digestion
- grips food and positions it between the teeth
- mixes food with saliva
- forms a bolus of food
- intiates swallowing
stomach
c/j shaped
15-25 cm long
small intestine - divisions
Duodenum - 25cm long (5%)
Jejunum - 2.5m long (40%)
Ileum -3m long (55%
duodenum structure
• Surrounds the head of the pancreas
• Receives
Gastric chyme from the stomach
Digestive juices from the pancreas
Bile from the live
duodenum
The mucosa has villi to increase the surface area
Its function is to breakdown food using enzymes
It uses hormones to regulate the rate of stomach emptying
jejunum
Has villi
• Has large circular folds to increase surface area of
mucosa
• Main function is to absorb previously digested food from the duodenum
ileum
• There isn’t an obvious junction between the
jejunum and ileum
• Has smaller and thinner walls than the jejunum
• Function
Absorb B12 and bile salts
Absorb remaining products not absorbed in the
jejunum
Absorption in the large bowel
Water
• Most water is absorbed in the large bowel
• The large bowel is important in maintaining homeostasis
Bacterial products
• Including vitamins – B and K
What are the functions of the liver?
digestive
haematological
metabolism of nutrients
detoxification
mineral and vitamin storage
bile production
absorbs iron and vitamin K
liver divisions
• It is divided into 4 lobes
Left lobe
Right lobe
• Subdivided into the caudate and quadrate lobes
Hepatocytes
metabolise proteins lipids and vitamins
the gallbladder
• Sac like organ
• Situated on the inferior surface of the liver
• It stores and concentrates bile
• Bile passes from the liver to the gallbladder via the right and left hepatic ducts into the common hepatic duct
• The bile passes into the gallbladder via the cystic duct
Functions of the pancreas exocrine function
• Exocrine function
Has cells that secrete enzymes and alkaline pancreatic juices
These cause the gallbladder to contract and
release bile into the duodenum
Endocrine function
• There is secretion of
Insulin – lowers blood glucose
Glucagon – raises blood glucose
