Transcript Slide 1
Mammalogy
(Spring 2015 Althoff)
LEC 06A
Mammalian Digestive System BASICS
Maintenance Systems
• __________________ —various organs along the digestive tract (from teeth to large intestine) A) receives food B) digests & absorbs nutrients C) excretes undigestible parts (feces) • __________________ —lungs A) takes in O 2 from “outside” environment B) takes out CO 2 from “inside” environment • __________________ —kidneys, bladder, & tubes A) rids blood of metabolic wastes B) helps regulate fluid level & chemical content of blood
Maintenance
DIGESTIVE RESPIRATORY URINARY
Control Systems
Food - IN CO 2 OUT, O 2 IN _____________ OUT ______________OUT
FUNCTIONS
of the Digestive System Breakdown the food that we eat into
__________________
________
those molecules into the body Eliminate
__________________
waste
Breakdown
the food into small molecules
_________________
= process of breaking down food into simple molecules
Two types: ____________ ____________ = chewing, physical breakdown = digestive enzymes (catabolism)
Foodstuffs broken down into simple molecules: Proteins amino acids Carbohydrates monosaccharides Lipids glycerol and fatty acids
ABSORB
the simple molecules
_______ doesn’t really “enter” the body until it is absorbed
Must pass through: _________________
blood stream
Unfortunately, we do not
___________
the process of absorption….animals designed to maximize extraction of nutrients from “resources” ingested.
This leads to the issue of gaining weight if we overeat.
ELIMINATE
non-digestible waste Any compound of food (emphasis “food”) we
_______________
will be
eliminated.
Ex. for humans: Cellulose (found in cell walls of plants)
_______
in normal, functioning human being
,
contains no undigestible material…so very little waste.
Organs of the DIGESTIVE System
• Mouth • Pharynx-throat • Esophagus • Stomach • Small Intestine • Large Intestine • Rectum/Anus • Salivary glands • Pancreas • Liver • Gall bladder
Organs of the DIGESTIVE System
• Mouth • Pharynx-throat • Esophagus • Stomach • Small Intestine • Large Intestine • Rectum/Anus ___________organs • Salivary glands • Pancreas • Liver • Gall bladder
As each
organ
think…… and/or
“stop”
is examined, 1) FUNCTION--what is it 2) DIGESTION —does it occur here?
(i.e., mechanical or chemical) 3) ABSORPTION —does it occur here?
(are amino acids, fatty acids & glycerol, and simple sugars truly “entering” the body?)
Mouth
• Oral cavity that receives food • Tastebuds so we can taste food • • Salivary glands secrete saliva - moistens food to make easier to swallow - starts digestion of starches (pH ~7.0), some sugars
____
ABSORPTION,
small
amt. of digestion • Some bacteria destroyed • Mastication of food—
__________________
for digestive juices to work on
MASTICATION: DIFFERENT TEETH FOR
DIFFERENT
DIETS HERBIVORES: flat premolars & molars HUMANS: variety CARNIVORES: killing (canines), shearing (premolars & molars
MASTICATION: “chewing” differences A Mandibular
________
and
________
groups Position of the condyle (arrow) relative to the plane of teeth differs between carnivores (A) and herbivores (B). Thus, the
___________
muscles (1) are primary group of chewing muscles for carnivores, whereas the
___________
(2) are the primary group for herbivores B 1 2
Fig. 4-193 p64 FDVMK
Pharynx
• Swallowing, no voluntary control • Food now called “
BOLUS
”
___
absorption,
___
digestion
Esophagus
• Tube from pharynx to stomach • Food moves by
PERISTALIS
…smooth mucsle contractions • Passes lower esophageal sphincter into stomach: a) prevents backup b) acidic gastric juices backup…heartburn results because lining irritated
Stomach
• J-Shaped organ • Functions: 1) store meal for 2 hours 2) small amt. of protein digestion 3)
_____
bacteria in bolus “if it can get to it” • pH of 2.0 with HCl added
Stomach…continued
• Muscus secreted protects stomach lining from pH of 2.0 – ulcers result if insufficient • HCl breakdowns down connective tissue • Pepsin enzyme starts protein digestion •
____________
,
_____ ________
(alcohol & some vitamins • Bolus
chyme (vomit)
as it leaves stomach
Ruminants: 4 chambered stomach
Small Intestine (SI)
• 9-10 ft. in adults • Functions:
__________ __________
“big time” & • Walls of SI lined with
_________
– tremendous amt. of surface area
Microvilli : area of absorption, link to transport systems ( cardiovascular & lymphatic capillaries )
Individual cells have ___________
Small Intestine (SI)
•
_____
chemical digestion: -
pancreatic juices
breaks down proteins & carbs.
Buffers chyme to pH 7.0 (from 2.0) -
bile
from liver and gall bladder.
Emulsify fats Lipase —break down triglycerides
Small Intestine (SI)
•
______
absorption: -
amino acids -simple sugars fatty acids…..
all to the liver via the bloodstream
Different diets, different SI designs
HIGH
in protein (meat)
CARNIVORES LOW
in protein (vegetation)
HERBIVORES
Large Intestine (LI)
• 4.5-5 ft in adults • After first few inches, considered colon • Functions: -
_____
digestion (some vitamins--in cecum)
_____
water
absorption
of
Large Intestine (LI)…con’t
• •
Diarrhea
—LI doesn’t get enough time to do its job…that is to remove water from wastes. A good “thing” if overload of bacteria present
Constipation
—LI tract not moving things through at regular pace, more water removed than normal, feces hard •
POLYPS
– found here, in epithelial tissue…. caused by cancer
Auxillary Organs: __ DIGESTION, __ ABSORPTION
• • •
LIVER
— function here is producer of bile. Contains components of dead red blood cells, giving feces color. Bile emulsifies fat. Removes toxic substances from foods upon arrival from blood stream. Stores excess nutrients from blood (sugar & vitamins). Cannot live without.
GALL BLADDER
— stores bile between meals. Secretes bile into SI. Can live without. Gall stones form when cholestrol content of bile comes out of solution (crytallizes)…oh my!
PANCREAS
– secretes pancreatic juices which contain enzymes (i.e., lactase is an example) and buffering solution (raises pH). Can not live without
SUMMARY - Digestion • Mouth • Phyarnx • Esophagus • Stomach • Small Intest.
• Large Intest.
• Pancreas • Liver • Gall Bladder