Test 3 Flashcards
Chemical Digestion
Enzymatic breakdown of large molecules into monomers
protection
- the mucus secretions in the stomach that help protect the mucosa against HCl
- Protection of the body against infection (acids, enzymes, lymphatic tissues destroy infectious particles.
what are the parts of digestion
Ingestion mechanical digestion chemical digestion absorption defecation protection propulsion
catabolism
the breaking of large molecules to smaller molecules
protein
subunits: amino acids
enzyme: Protease
carbohydrate
subunit: simple sugars
enzyme: amylase
lipids
subunit: fatty acids
enzyme: lipase
peritoneum
a serous membrane (double-layered membrane with fluid in between) that lines the abdominal cavity.
visceral peritoneum
exterior surface of abdominal organs
parietal peritoneum
lines the body wall.
What is the fluid in the peritoneum called
Peritoneal fluid
mesentery
double-fold of peritoneum that is fused together; mesenteries extend from the body wall to the organs.
reason for mesentery
- To hold and support blood vessels, lymphatic vessels, and nerves that supply the organs of digestion.
- To hold organs in place in the body (prevent intestines from becoming tangled, help resist the force of gravity against the organs)
- Fat storage.
types of movement in the digestive tract
- Propulsion
- Segmentation
propulsion
is the term for food moving distally (away from mouth) in the GI tract.
two parts of propulsion
swallowing and peristalsis
peristalsis
are alternative waves of contraction and relaxation of muscles
segmentation
segments of the GI tract contract and relax.
-Food is moved forward and then backwards, this is a kind of mechanical processing to mix and break down food. Non-directional movement (is not propulsive)
parts of the alimentary canal
- Mucosa (closest to lumen), 2. Submucosa 3. Muscularis Externa 4. Serosa (or adventitia)
functions of mucosa
Secretes mucus (goblet cells)
May secrete enzymes
Often absorbs monomers
Acts as a barrier that protects the body from infection
potential parts of the mucosa
Epithelium
- Lamina propria (connective tissue)
- Muscularis mucosae
submucosa
Made of dense connective tissue
Contains nerves, lymph & blood vessels, glands are often located in this layer.
May contain specialized structures like Peyer’s Patches (Ileum) and Brunner’s glands (duodenum)
Peyer’s patches
masses of lymphoid tissue that fights infection.
located in the ileum
brunner’s glands
secrete alkaline (high pH) mucus that helps to neutralize stomach acid located in the duodenum
muscularis externa
Muscularis Externa:
Mixes/propels food
Usually 2 layers of smooth muscle: Circular and Longitudinal
Innervated by myenteric plexus nerves
Serosa/adventitia
Contains epithelium & connective tissue
The serosa layer is made of visceral peritoneum (reduces friction)
In some parts of the GI tract (esophagus), this outer layer is adventitia, a fibrous layer that attaches the part of the body wall (different then the function of serosa).
serosa compared to adventitia
serosa is visceral peritoneum and adventitia is a fibrous outer layer that is used to connect to the alimentary canal to the things around it.
nervous system control
Short reflexes:
Long reflexes:
Short reflexes
: controls segmentation and peristalsis
Long reflexes
integrates the central nervous system and extrinsic autonomic nervous system, either enhancing or inhibiting digestive activities.
local factors
pH, physical or chemical stimulation.
hormonal
18+ hormones that control most aspects of GI function.
things that control the digestive process
nervous system
local factors
hormonal
digestive processes that occur in the oral cavity
Ingestion (this only happens in the mouth!)
Begins mechanical breakdown by chewing
Starts chemical digestion (breakdown of carbohydrates by salivary amylase)
Initiates propulsion by swallowing
types of teeth
- Incisors cut food
- Canines tear food
- Premolars crush food
- Molars grind food
make up of saliva
- Water (the main ingredient)
- Electrolytes (like K+, Cl-, Na+)
- Proteins, including enzymes and mucins
- Antibodies and lysozyme (inhibit infection)