GI System Flashcards
What do bile salts do?
Emulsify fat
What is blood detoxification?
Liver takes water insoluble compounds, adds chem groups to make them water soluble, allowing the kidneys to excrete them
Microsomal enzymes/P450 system refers to
Liver enzymes
What do microsomal enzymes do?
Inactivate compounds
If a person has low levels of microsomal enzymes, what effects do drugs have on them?
Bigger effects
If a person has higher levels of microsomal enzymes, what effects do drugs have on them?
Lower effects
When does jaundice occur in adults?
If bile secretion is blocked or liver is nonfunctional
What is hepatotoxicity
Liver disease
What are the 3 phases of control
- cephalic phase
- gastric phase
- intestinal phase
Cephalic phase
Vagus n. stimulates gastric secretion before food is swallowed.
Gastric phase
Food stretches stomach activating myenteric & vagovagal reflexes.
Gastric secretion stimulated.
Histamine & gastrin also stimulate acid & enzyme secretion.
Intestinal phase
Arriving of chyme into duodenum. Gastric function stopped due to inhibitory signals being sent.
What are enterogastrones
Hormones that inhibit gastric motility
Types of enterogastrones
- GIP (gastroinhibitory peptide)
- CCK (cholecystokinin)
- Secretin
GIP
Stimulates pancreatic insulin production from islets; secreted by duodenum in response to carbs & lipids
CCK
Secreted in response to fat & protein in chyme
Stimulates gallbladder contraction & release of pancreatic juice
Secretin
In response to acidic intestinal pH
Stimulates bicarb from panreas
What does the ENS control
Neurons & glia in gut
Interconnected by outer myenteric & inner submucosal
What does the outer myenteric control
Motor activity
What does the inner submucosal control
Secretion, absorption, local blood flow
Sensory Neurons
Extrinsic afferents: travel outside of gut
Intrinsic afferents: localized
Intestinal reflexes
Gastroileal reflex: increased motility of ileum
Ileogastric reflex: distension of ileum, decreased gastric motility
Intestino-intestinal reflex: overdistension of 1 segment - relaxation of rest of intestine
What is in pancreatic juice
Bicarb- to help neutralize acid in stomach
Enzymes
CCK
Secreted in response to protein & fat in duodenum
Stimulates release of pancreatic enzymes
What does secretin get produced in response to
Acid
Digestion beings in the
Mouth
Exocrine V. Endocrine secretion
Exocrine: secrete into duct; far reaching
Endocrine: secrete into bloodstream; work locally; hormones
What does digestion do?
Breaks food down into smaller subunits
Chemical breakdown
Breaking of CHEMICAL BONDS by small intestine
Mechanical breakdown
Chewing/ churning of stomach
What is absorption?
Going from lumen of digestive tract into bloodstream or lymph
What happens after absorption?
Delivered to tissue for energy storage
Lymph absorbs..
Fats
What is the problem with digestion?
Enzymes can digest tissue of digestive tract
Which get absorbed?
Fatty acids, monosaccharides, & amino acids
Peristalsis
Moves forward
Where does peristalsis occur
The esophagus, stomach, & intestines
Digestive system function
Motility, ingestion, secretion
Mastication
Chewing
Deglutition
Swallowing
What does digestion allow
Absorption
Where is food stored & why?
In stomach to get a continuous stream of nutrients entering blood, so that you don’t need to eat continuously
Purpose of HCL
Provides a nonspecific immune defense against ingested pathogens
Peyers patches
Area of lymphoid tissue in intestinal tract; also protect against pathogens https://image.slidesharecdn.com/lymphaticsystemnotes-120330134955-phpapp01/95/lymphatic-system-notes-14-728.jpg?cb=1333115791
What protects immune function?
Tight junctions, Hcl, Peyers patches
Digestive tract refers to
Mouth –> anus
GI tract refers to
Stomach & intestines
Which layer is in contact with ingested food
Mucosa
Layers of the GI tract
Mucosa: innermost; lines lumen
Submucosa: below mucosa
Muscularis:
Serosa: outer connective
Goblet cell function
Produce mucus; helps things move along
Submucosal plexus
Regulates secretion; located in submucosa
Mucosa function
Absorption & secretion; lines lumen; simple columnar epithelium; has goblet cells
Submucosa function
Secretion; contains glands & nerve plexuses; vascular connective tissue layer
ENS function
Detects pH, detects food ingested, has sensory neurons (brain of the GI system)
How is food broken down?
Proteins –> amino acids
Fats –> fatty acids & glycerol
Carbs –> monomeric sugars
What is segmentation?
Mixing with digestive enzymes
Muscularis function & components
Segmentation & peristalsis; Inner circular & outer longitudinal layer; smooth muscle; myenteric plexus
Myenteric plexus innervation & location
Innervation: sympathetic & parasympathetic
Location: between 2 muscle layers
Myenteric plexus function
Major nerve supply to GI tract; movement contraction or relaxation of muscle layers
Esophagus connects
Pharynx –> stomach
Esophagus
Voluntary –> Involuntary; posterior to trachea; stratified squamous