L1 & L2: Comparative GIT Anatomy Flashcards
Food is considered to be outside the body until nutrients are absorbed by the small intestine. T or F?
True, of course
Describe the basic differences in the GIT b/w different species and how these differences relate to diet
Describe the process of motility
- Mixing of ingested material with secretions
- Peristalsis - contraction of smooth muscle of digestive tract to move food along (squeeze behind, relax in front). All animals do this.
- Rate of food movement depends of feed & species
- Rumen & reticulum have convulsive motility “waves”
Describe the process of digestion
- Breakdown of food into constitutent molecules small enough to be absorbed
- physical (mechanical)
- chemical (enzymatic)
- Aided by digestive secretions (enzymes) and mixing (motility)
Describe the process of secretion
- Release of substances within the body to aid digestion
- enzymes
- buffers
- bile salts (emulsify fats)
- lubricants
- solvents
Describe the process of absorption
- Needs to occur for body to use nutrients
- Occurs across specialised absorptive cells lining lumen
- Either passive (diffusion) or active (carrier mediated)
Basic components of mammalian digestive tract
The mouth, lips, teeth and tongue are used for?
prehension and mastication, lubricating
Basic components of mammalian digestive tract
Describe the pharynx and oesophagus
- Common passage for food and air
- pharyngeal muscles force food from pharynx
Basic components of mammalian digestive tract
Describe the monogastric stomach and its role
- Lying under diaphragm
- separated from oesophagus by cardiac sphincter
- separated from SI by pyloric sphincer
Role:
- Mix food
- reservoir of material supply to SI
- begins digestion by secreting gastric juices
- Digesion occurs primarily via HCL from parietal cells
- Pepsinogen (inactive form of Pepsin -protein digestor) secreted by chief cells
- Pepsinogen activated by low pH (HCL)
- glandular digestion
Basic components of mammalian digestive tract
Describe the monogastric stomach glands
- Cardiac glands => mucus
- Fundic (gastric) glands => mucus, HCL, pepsinogen (pepsin)
- Body => gastric digestion
- Pyloric glands => mucus, sml amount pepsinogen
Basic components of mammalian digestive tract
Describe avian GIT
- Glandular (true) stomach is proventriculus
- Followed by ventriculus (gizzard)
- Cloaca -passes faeces & urine mixed
Basic components of mammalian digestive tract
Describe the ruminant stomach and its components
- Digest cellulose & CHD
- 4 compartments, 3 sections
- fore-stomach (reticulum & rumen) => microbial fermentation
- Bible (omasum) => water absorption
- True stomach (abomasum) => glandular
- Reticulo-rumen contains water & microbes at alkaline pH and warm temp
- Rumen has villied surface, absorb VFA
- Reticulum has honey comb surface increase breakdown
- Omasum, absorbs water & some VFA
Basic components of mammalian digestive tract
describe the SI
- digesta moves quickly ~about 30cm/min
- Mobile
- 3 parts
- duodenum: pancreatic & bile ducts empty into
- jejunum: absorb carbs & protein (villi, micro-villi, brush border)
- ileum:
Basic components of mammalian digestive tract
describe the LI
- 3 parts
- Caecum
- Colon (large and small)
- Rectum
- L colon: 4 regions, site of most fermentation (VFA)
Basic components of mammalian digestive tract
list the accesory digestive organs and briefly describe their role
- Salivary glands: parotid, mandibular, sublingual (major)
- Liver: secretes bile, energy storage (glycogen), processes absorbed nutrients, breakdown of RBC (bilirubin)
- Pancreas:
- exocrine secretes via ducts (sodium bicarb & digestive enzymes). Outside body.
- endocrine secretes into blood (ductless) hormones insulin, glucagon, somatostatin
- Associated SI glands:
- Brunner’s glands
- Crypts of Lieberkuhn
- Peyer’s patches
