GI Part 1 & 2 Flashcards
(60 cards)
What are the 4 basic layers of the alimentary canal?
From Inner–> outer
- Mucosa
- Submucosa
- Muscularis externa
- Serosa or Adventitia
What are the 3 sections in mucosa?
- Epithelium
- stratified squamous or simple columnar - Lamina propra
- loose connective tissue
- helps with absorption
- Contains MALT - Muscularis mucosae
- smooth muscle
- moves mucosa
What are some functions of mucosa?
- SECRETES mucus, enzymes, hormones
- ABSORBS end products of digestion
- PROTECTS against infectious disease
Explain the submucosa layer.
Function?
- Loose connective tissue
- Has blood & lymphatic vessels
Function:
- support mucosa
- Binds layers together (loose connective)
What are the layers in the muscularis externa?
Function?
- Circular layer
- Longitudinal layer
- Myenteric nerve plexus
Function
- segmentation & peristalsis
- sometimes forms sphincters to control passage/prevent backflow
Explain process of Peristalsis
- Circular muscle contract BEHIND bolus
- Longitudinal muscles contract AHEAD of bolus
- moves bolus forward
Explain the process of segmentation
Contracting & relaxing adjacent segment to move food forward and backward for mixing
Explain serosa layer. Function?
Which organs have the adventitia layer? Explain it.
Serosa
- loose connective tissue
- simple squamous
Function: permit mobility
Adventitia
- retroperitoneal organs
- dense irregular CT to bind organs together
- Lack mobility (anchored)
What is the peritoneum?
What is the peritoneal cavity?
Serous membrane of abdominal cavity
Peritoneal cavity
- between visceral & parietal peritoneum, fluid lubricates mobile organs
What are the intraperitoneal organs?
What do they have?
Mesentery
- double layer of peritoneum
- route for blood vessels, lymphatics & nerves
- Holds organs in place & stores fat
organs
- liver
-stomach
- ileum & jejunum
- transverse colon
- sigmoid colon
Differentiate between dorsal and ventral mesentery?
Dorsal
- allows access to all the blood vessels, lymphatics & nerves
Ventral
- for anchoring
- have low blood supply
Explain retroperitoneal organs.
Which organs are they
Lack mesentery
- resorbed & lost
Organs
- Duodenum
- Ascending colon
- Descending colon
- Rectum
- Pancreas
What type of fibres in the enteric nervous system link to CNS?
Afferent visceral fibers (to brain)
What 2 types of plexus’ are in the Enteric Nervous system?
Explain their function
- Myenteric nerve plexus
- controls GI tract motility - Submucosal nerve plexus
- Regulates glands & smooth muscle (including BV) in mucosa
What are the 3 mechanisms that regulate & control digestive activities?
- Local factors
- primary stimulus for digestive activities
- Include: lumen pH, physical distortion , presence of chemicals - Neural control
- short reflex (myenteric plexus)
- long reflex ( control large peristaltic waves) - Hormonal control
- produces enteroendocrine cells (digestive hormones)
What are some functions of saliva
- cleanses mouth
- moistens & dissolve food chemicals
– Aids in bolus formation
– Contains enzymes to begin digestion – Buffers pH (bicarbonate)
– Lubrication
What types of cells are in the following
Submandibular
Parotid
Sublingual
Intrinsic glands
Submandibular: serous & mucous cells
(MOST OF total saliva volume)
Parotid: serous cells
Sublingual: mucous cells
Intrinsic glands: serous & mucous cells
What proteins and enzymes does saliva have?
Proteins:
- mucin, lysozyme, IgA, albumin
Metabolic wastes: urea & uric acid
What is the role of intrinsic glands vs extrinsic glands?
Intrinsic: keep mouth moist
Extrinsic:
- smell, taste, sight
- parasympathetics, CN IX, CN VIII
What is the hardest substance in the body?
enamel
What is dentin maintained by?
odontoblasts of pulp cavity
What is pulp?
connective tissue, blood vessels & nerves inside teeth
What is cementum anchored by?
periodontal ligament
What is the difference between the layers in the esophagus and alimentary canal?
-Mucosa is stratified squamous
- submucosa is areolar connective tissue