Intro To Histology Of Git Flashcards
THE GIT
Also called the digestive tract or alimentary canal consists of the:
THE GIT
Also called the digestive tract or alimentary canal consists of the:
▪ Oral cavity
▪ Esophagus
▪ Stomach
▪ Small and large intestines ▪ Anus
PROCESSES OF DIGESTION
The processes involved include:
processes involved include:
Ingestion
Mastication
Peristalsis/motility
Secretions
Hormone release
Chemical digestion
Absorption
Elimination
GENERAL STRUCTURE OF THE DIGESTIVE TRACT
The entire gastrointestinal tract has certain common structural characteristics
It is a hollow tube with a lumen of variable diameter and a wall made up of four main layers:
GENERAL STRUCTURE OF THE DIGESTIVE TRACT
The mucosa
The submucosa
The muscularis
The serosa
THE MUCOSA
Consists of:
THE MUCOSA
Consists of:
Epithelial lining
Lamina propria
Muscularis mucosae
Muscularis mucosae
❑ (MM)- thin layer of ——
❑ MM usually separates the —- from —
❑ Allows local movements of the mucosa
Mucosa is frequently called a ——
Muscularis mucosae
❑ (MM)- thin layer of smooth muscle
❑ MM usually separates the mucosa from submucosa
❑ Allows local movements of the mucosa
Mucosa is frequently called a mucous membrane
THE LAMINA PROPRIA
Zone of loose connective tissue rich in:
THE LAMINA PROPRIA
⚫
Zone of loose connective tissue rich in:
Blood vessels Lymphatics Lymphocytes Smooth muscle cells
oftentimes small glands are present
THE SUBMUCOSA
The submucosa contains denser connective tissue with:
• ———
• —— plexus of autonomic nerves
• ———-(may be present)
THE SUBMUCOSA
The submucosa contains denser connective tissue with:
• larger blood and lymph vessels
• Submucosal (Meissner) plexus of autonomic nerves
• Glands and lymphoid tissues (may be present)
THE MUSCULARIS (MUSCULARIS EXTERNA)
❑ Thick muscularis is composed of smooth muscle cells organized into 2 or more sublayers
❑ Internal sublayer = —-
❑ External sublayer = ——
❑ Connective tissue between the muscle sublayers contains:
❑ ——-
❑ ——-
❑ Another autonomic nerve plexus= the ————) nerve plexus
THE MUSCULARIS (MUSCULARIS EXTERNA)
❑ Thick muscularis is composed of smooth muscle cells organized into 2 or more sublayers
❑ Internal sublayer = Circular
❑ External sublayer = Longitudinal
❑ Connective tissue between the muscle sublayers contains:
❑ Blood vessels
❑ Lymph vessels
❑ Another autonomic nerve plexus= the Myenteric (Auerbach) nerve plexus
THE LOCAL ENTERIC NERVOUS SYSTEM
The —— and —— nerve plexuses constitutes the local enteric nervous system of the digestive tract
This system functions independently of the ——
——- plexus is responsible for the local contraction of the muscularis which mix and propel the contents of the lumen= peristalsis
THE LOCAL ENTERIC NERVOUS SYSTEM
The submucosal and myenteric nerve plexuses constitutes the local enteric nervous system of the digestive tract
This system functions independently of the CNS
Myenteric plexus is responsible for the local contraction of the muscularis which mix and propel the contents of the lumen= peristalsis
THE SEROSA
Is the —— layer of the GI tract located within the abdominal cavity
Is a thin sheet of loose connective tissue rich in ❑ Blood vessels
❑ lymphatics and ❑ Adipose tissue
o and covered with ——= a simple squamous covering epithelium
THE SEROSA
Is the outermost layer of the GI tract located within the abdominal cavity
Is a thin sheet of loose connective tissue rich in ❑ Blood vessels
❑ lymphatics and ❑ Adipose tissue
o and covered with Mesothelium= a simple squamous covering epithelium
THE SEROSA CONT’D
The serosa of the small and large intestines is continuous with parts of the ——
——= large fold of adipose connective tissue, covered on both sides by mesothelium, that suspends the intestines and is continuous with the peritoneum
——= serous membrane lining the abdominal cavity
Because the esophagus is not suspended in a cavity but bound directly to adjacent structures, instead of a serosa, it has a thick ——
The adventitia consists of connective tissue containing vessels and nerves, lacking ——
THE SEROSA CONT’D
The serosa of the small and large intestines is continuous with parts of the mesentery
Mesentery= large fold of adipose connective tissue, covered on both sides by mesothelium, that suspends the intestines and is continuous with the peritoneum
Peritoneum= serous membrane lining the abdominal cavity
Because the esophagus is not suspended in a cavity but bound directly to adjacent structures, instead of a serosa, it has a thick adventitia
The adventitia consists of connective tissue containing vessels and nerves, lacking mesothelium
FUNCTIONS OF THE DIGESTIVE TRACT’S EPITHELIAL LINING
FUNCTIONS OF THE DIGESTIVE TRACT’S EPITHELIAL LINING
Provide a selectively permeable barrier between the contents of the tract and the tissues of the body
Facilitate the transport and digestion of food
Promote the absorption of the products of this
digestion
Produce hormones that affect the activity of the digestive system
Produce mucus for lubrication and protection
IMMUNOLOGIC SUPPORT OF THE GASTROINTESTINAL TRACT
The abundant free immune cells and lymphoid nodules in the mucosa and the submucosal layers, constitute the ——
The digestive tract normally contains thousands of microbial species, including both—— of the gut as well as ——— ingested with food and drink
The entire digestive tract, with the exception of the—-, —— and —— is lined by a simple thin vulnerable epithelium
IMMUNOLOGIC SUPPORT OF THE GASTROINTESTINAL TRACT
The abundant free immune cells and lymphoid nodules in the mucosa and the submucosal layers, constitute the MALT (Mucosa-Associated Lymphoid Tissue
The digestive tract normally contains thousands of microbial species, including both useful inhabitants of the gut as well as potential pathogens ingested with food and drink
The entire digestive tract, with the exception of the oral cavity, esophagus and anal canal is lined by a simple thin vulnerable epithelium
IMMUNOLOGIC SUPPORT OF THE GASTROINTESTINAL TRACT CONT’D
The mucosa-associated immune defense system, provides an essential backup to the thin physical barrier of the epithelial lining
The lamina propria located just below the epithelium is a zone rich in —— and —— some of which actively produce antibodies
These antibodies are mainly immunoglobulin——
IMMUNOLOGIC SUPPORT OF THE GASTROINTESTINAL TRACT CONT’D
The mucosa-associated immune defense system, provides an essential backup to the thin physical barrier of the epithelial lining
The lamina propria located just below the epithelium is a zone rich in macrophages and lymphocytes some of which actively produce antibodies
These antibodies are mainly immunoglobulin A (IgA)
IMMUNOLOGIC SUPPORT OF THE GASTROINTESTINAL TRACT CONT’D
These antibodies undergo —— into the intestinal lumen bound to the ——produced by the epithelial cells
This complex protects against viral and bacterial pathogens
IgA is resistant to proteolytic enzymes and can therefore coexist with the proteases present in the lumen
IMMUNOLOGIC SUPPORT OF THE GASTROINTESTINAL TRACT CONT’D
These antibodies undergo transcytosis into the intestinal lumen bound to the secretory protein produced by the epithelial cells
This complex protects against viral and bacterial pathogens
IgA is resistant to proteolytic enzymes and can therefore coexist with the proteases present in the lumen
