CH 41 - GOT FAT?

Villi and Microvilli

- folds inside the small intestine that increase the surface area for absorption - many blood vessels go to them - molecules are absorbed into blood stream - increase surface area of intestine to allow for optimal absorption

List major secretions that enter duodenum and where they come from

- inactive proteases from pancreas - bile from liver - acid chyme from stomach

Two major functions of the small intestines

- most chemical digestion - digested food is sent to blood

What two major changes occur to food in the mouth?

1- it is cut/pulverized into smaller pieces 2- salivary amylase begins polymer breakdown

List three functions of the hydrochloric acid/HCl of the stomach

1- kills pathogens/microbes 2- pH2 → effective pepsin breakdown of proteins 3- emulsify food and protect against bacteria

Overview of Food Processing! 👄🍕

1. Ingestion 2. Digestion (through enzymatic hydrolysis, extra/intracellular feeding, or alimentary canals) 3. Absorption (cells take up small molecules) 4. Elimination (removal of undigested material 💩)

Essential Amino Acids

8 amino acids that must be obtained in a diet

Hepatic portal vessel

A large circulatory channel that conveys nutrient-laden blood from the small intestine to the liver, which regulates the blood's nutrient content

Intracellular feeders

Break down food inside cells

Extracellular feeders

Break down food outside cells

Undernourishment

Caloric deficiency

Alimentary canals

Digestive track

In the Small intestine...

Duodenum, bile

Bulk-feeders

Eat large pieces of food

Malnourishment

Essential nutrient deficiency

Over-nourishment

Excessive food intake

In the Stomach...

Gastric juice, pepsin(active)/pepsinogen(inactive), acid chyme, pyloric sphincter

Opportunistic Feeding

Herbivore 🐄, Omnivore 💃, Carnivore 🐆

Minerals

Inorganic cofactors

Distinguish between intracellular digestion and extracellular digestion.

Intracellular - happens inside the cell Extracellular - happens outside the cell (like the breaking down of food through gastric acid/contraction of smooth muscle)

Breaking those Nucleic Acids down!

LUMEN OF SMALL INTESTINE DNA+RNA → (pancreatic nucleases) → nucleotides EPITHELIUM OF SMALL INTESTINE Nucleotides → (nucleotidases) → nucleosides → (nucleotidases and phosphatases) → nitrogenous bases, sugars, phosphates

Breaking those Fats down!

LUMEN OF SMALL INTESTINE Fat globules → (Bile salts) → Fat droplets →(pancreatic lipase) → glycerol, fatty acids, glycerides

Substrate-feeders

Live in/on food

Essential nutrients

Materials that must be obtained in preassembled form

How is the stomach itself protected from being digested of damaged by pepsin or HCl?

Mucous layer of cells lines the lumen and constantly replace themselves

Breaking those Carbs down! 🍞

ORAL CAVITY 👅 Polysaccharides → (salivary amylase) → smaller polysaccharides LUMEN OF SMALL INTESTINE Polysaccharides → (pancreatic amylase) → disaccharides EPITHELIUM OF SMALL INTESTINE Disaccharides → Monosaccharides

Vitamins

Organic coenzymes

heterotrophs

Organisms that cannot make their own food

Autotrophs

Organisms that make their own food

How does food move down the esophagus?

Perystalsis (rhythmic waves of contraction by smooth muscle)

Peristalsis

Rhythmic waves of contraction by smooth muscle

Sphincters

Ring-like valves that regulate passage of material

Breaking those Proteins down! 🍖

STOMACH Protein → (Pepsin) → smaller polypeptides LUMEN OF SMALL INTESTINE More Polypeptides → (trypsin and chymotripsin) → smaller polypeptides All those small polypeptides → (carboxypeptidase) → amino acids EPITHELIUM OF SMALL INTESTINE Small proteins and amino acids → (dipeptidases, carboxypeptidases,and aminopeptidases) → amino acids

In the Oral cavity...

Salivary amylase, bolus, pharynx, epiglottis, esophagus

Accessory glands 👜👒

Salivary glands, pancreas, liver, gall bladder

Suspension-feeders

Sift food from water 🐋

Fluid-feeders

Suck fluid from host 🕷

How are the parietal cells of the stomach protected from digesting themselves by pepsin?

The stomach is protected by the epithelial cells, which produce and secrete a bicarbonate-rich solution that coats the mucosa. Bicarbonate is alkaline, a base, and neutralizes the acid secreted by the parietal cells, producing water in the process. This continuous supply of bicarbonate is the main way that your stomach protects itself from autodigestion (the stomach digesting itself) and the overall acidic environment.

Sphincters in the digestive system

They act as valves to control the flow of partially digested food

Salivary glands 👅

Tongue, parotid gland, sublingual gland, submandibular gland

Essential fatty acids

Unsaturated fatty acids

gastric inhibitory peptide (GIP)

decreases stomach churning → slows emptying of stomach

Evolutionary Adaptations of recent digestive systems?:

dentition (teeth assortment), length of digestive track, symbiosis (with the bacteria in our intestines), ruminants (multiple stomachs of cows/other animals with multiple stomachs)

Mechanisms of absorption of different nutrients by small intestines

diffusion - fat molecules sodium in/dependent transporters - sugars and amino acids chylomicrons - fats

nutritional adaptation of animals that practice coprophagy

feces of large herbivores contain substantial amts of semi-digested foods

Regulation of blood glucose levels

if too low: liver converts glycogen to glucose and then releases glucose into bloodstream if too high: insulin is released and glucose is converted to glycogen for storage

where are fats digested?

lumen of the small intestine

Lacteal

lymphatic capillary that absorbs dietary fats in the villi of the small intestine

where are carbs digested?

mouth and small intestine

Explain the adaptation that protects the pancreas from digesting itself by the peptidases it produces

pancreatic enzymes are only activated once in the small intestine

What is the function of the epiglottis?

prevent mixing of food and air cavities

why are essential nutrients "essential"?

since they cannot be created in the body, they must be consumed

where are nucleic acids digested?

small intestine

cholecystokinin (CCK)

stimulates release of digestive enzymes to pancreas; emptying bile in gall bladder

Gastrin

stimulates release of gastric acid

secretin

stimulates secretion of sodium bicarbonate to pancreas and bile to liver

where are proteins digested?

stomach and small intestine

coprophagy

the eating of own feces

Why must animals eat food?

they cannot make their own food for energy

Adaptations of the small intestines that enhance its function

villi and microvilli absorb nutrients and send them to blood; epithelial tissues secretes mucous and enzymes