GI Intro Flashcards
(16 cards)
The GI tract functions
as a major link in the exchange of material and energy between the ——- and the —— environment.
• It is composed of a long muscular tube (called ——) extending from the —- to the ——, and a set of accessory organs.
The GI tract functions
as a major link in the exchange of material and energy between the body and the external environment.
• It is composed of a long muscular tube (Gl tract/ alimentary canal) extending from the mouth to the anus, and a set of accessory organs.
The accessory organs include
Tongue
Teeth
Exocrine part of pancreas
Liver
Salivary gland
Gall bladder
The GI system provides the body with a continuous supply of —-,—-,—- and to achieve this requires:
1.
2.
3.
4.
5.
Water,electrolytes,nutrients
1. Movement of food through alimentary canal
2. Secretion of digestive juices and digestion of the food
3. Absorption of the digestive products, water and the various electrolytes
4. Circulation of blood through the GI organs to carry away the absorbed substances
5. Control of all these functions by the hormonal and nervous systems
General organization of GIT
From the mouth to anus, digestive canal is lined by ——— membrane (also called—-.)
• in the mouth, esophagus and anus, the epithelial layer is of a — —- variety about —- to —cells thick
• in the region fo absorption and secretion, a ———— layer of epithelium is found. This region is also characterized by folding and the presence fo finger-like projections called, —-.
General organization of GIT
From the mouth to anus, digestive canal is lined by mucous membrane (also called mucosa-.)
• in the mouth, esophagus and anus, the epithelial layer is of a stratified squamous variety about 10 to 15
cells thick
• in the region fo absorption and secretion, a single layered columnar epithelium layer of epithelium is found. This region is also characterized by folding and the presence fo finger-like projections called, villi
GENERAL ORGANIZATION OF GIT
From the outer(serosal ) to the inner( luminal) , the tissue layers of the GIT are
Serosa
Longitudinal muscle
Myenteric plexus
Circular muscle
Submucosa
Mucosa
MUCOSA
It is the ——— and major —— layer of the GIT.
It consists of a ——— epithelium supported by the lamina propria,a thin layer of areolar connecting tissue containing numerous —— ——( protection against disease)
• External to the lamina propria is a thin layer of smooth muscle called the ——-(muscle layer responsible for the numerous small folds in certain portions of the Gl tract.
• These folds greatly increase the absorptive surface area.
• Specialized goblet cells in the mucosa secrete mucus throughout most of the Gl tract.
MUCOSA
It is the absorptive and major secretory layer of the GIT.
It consists of a simple columnar epithelium supported by the lamina propria,a thin layer of areolar connecting tissue containing numerous lymph nodules( protection against disease)
• External to the lamina propria si a thin layer of smooth muscle called the muscularis mucose (muscle layer responsible for the numerous small folds in certain portions of the Gl tract.
• These folds greatly increase the absorptive surface area.
• Specialized goblet cells in the mucosa secrete mucus throughout most of the Gl tract.
SUBMUCOSA
This is a highly —— layer of connective tissue that serves the —-.
Absorbed molecules that pass through the ——- epithelial cells of the mucosa enter into blood and lymphatic vessels of the submucosa.
• It contains glands and nerve plexuses, the ——— plexus (Meissner’s plexus) which provides an autonomic nerve supply to the muscularis mucosae.
SUBMUCOSA
This is a highly vascular layer of connective tissue that serves the mucosa.
Absorbed molecules that pass through the columnar epithelial cells of the mucosa enter into blood and lymphatic vessels of the submucosa.
• It contains glands and nerve plexuses, the submucosal plexus (Meissner’s plexus) which provides an autonomic nerve supply to the muscularis mucosae.
Control of Gl function
In general, the motor and secretory activity of the Gl tract is regulated and coordinated by —— and ——.
• The nervous control can be divided into two components:
Control of Gl function
In general, the motor and secretory activity of the Gl tract is regulated and coordinated by nerves and hormones.
• The nervous control can be divided into two components:
1. Intrinsic nervous control (INC) (Enteric NS)
a. Myenteric plexus
b. Submucosal plexus
- can act independently of the ENC
- involves local reflexes confined to the wal of the gut itself e.g. peristaltic reflex.
Neurotransmitter of motor neurons
Ach
Substance P
Neurotransmitters of secretomotor neurons
Ach
VIP
Histamine
Inhibitory motor neurons that suppress muscle contractions
VIP
NO
ATP
Motility in the intestine is dependent purely on
Neural mechanism
Secretions from the liver and pancreas is regulated mainly by
Hormonal influence
Splanchnic bed (——- and —— mesenteric arteries), with the capilary system extending into all of the vili.
• Blood flows out of the tract through the —- veins, directly to the liver.
• This is the “-—” effect, whereby absorbed substances are routed directly to the liver (without entering niot the general circulation), where much processing occurs.
Splanchnic bed (superior and inferior mesenteric arteries), with the capilary system extending into all of the vili.
• Blood flows out of the tract through the portal veins, directly to the liver.
• This is the “first pass” effect, whereby absorbed substances are routed directly to the liver (without entering niot the general circulation), where much processing occurs.
Lymph —— (lymphatic capillaries) are found throughout the intestines and into the villi of the small intestine, alowing absorption of lipids .
• The lymphatic system is also extensive in the liver where it absorbs fluids and proteins and transports them to the systemic venous bolod.
• Lymphatic transport of proteins contributes substantially to plasma —- pressure and provides binding —- of circulating substances including hormones, calcium and iron
Lymph lacteals (lymphatic capillaries) are found throughouteht intestines anci into the villi of the smal intestine, alowing absorption of lipids .
• The lymphatic system is also extensive in the liver where it absorbs fluids and proteins and transports them to the systemic venous blood.
• Lymphatic transport of proteins contributes substantially to plasma oncotic pressure and provides binding nseioptr rof circulating substances including hormones, calcium and iron
8 functions of GIT
Digestion
Endocrine
Expulsion
Protection
Motility
Absorption
Secretion
Storage
