Digestion Flashcards
Whats assimilation?
Processes of nutrient acquisition, digestion, and absorption
What are 3 main nutritional needs:
- Organic building blocks
- Organic C and N to build macromolecules (carbohydrates, lipids, proteins, nucleic acids) - Energy
- fuel for ATP synthesis
3. Essential nutrients Vitamins Minerals Amino acids Fatty acids
What is energy provided in?
Calories
What are the essential vitamins? Functions and deficiency symptoms?
**Fat soluble** A. retinol- Visual; night blindness D. calciferol- ca and p absorption; ricketts E. tocopherol- antioxidant; anemia K. menadione- blood clotting; hemophilia **Water-soluble** B1. thiamin- beriberi B2. riboflavin- skin disorders B3. niacin- pellagra B5. pantothenic acid- adrenal and reproductive dysfunction B6. pyridoxine- peripheral neuritis Biotin- hair loss Folic acid- anemia B12. cobalamin- anemia C. ascorbic acid- scurvy
What are the 10 essential minerals?
Calcium, phosphorus, sulfur, potassium, chlorine, sodium, magnesium, iron, fluorine, and iodine.
Where are amino acids from?
animals
Whats protein quality?
The amino acid profile of dietary protein
What can animals make fatty acids from?
Acetyl coA
What acids can’t they produce?
Omega-3 and omega-6
How do cnidaria feed?
-Bring food into the gastrovascular cavity; digestion occurs extracellularly and intracellularly
-two-way gut- 1 opening for incoming and outgoing
simple internal sac
Sac may have diverticula to increase surface area
Whats a one-way gut (gastrointestinal tract)?
Mouth, pharynx, esophagus Stomach Gastric sphincter Upper or small intestines Cecum Lower or large intestines Rectum Anus
How is food pushed along the GI?
Peristalsis- wavelike muscle contractions
What are sphincters in the GI?
Valves that regulate movement of material between compartments
What are accessory glands?
gall bladder, liver, pancreas, salivary glands
What are teeth for?
Mechanically break down food
What are salivary glands for?
- Saliva
- Salivation is controlled by nerve signals: Parasympathetic and Sympathetic
Whats the stomachs function?
-Stomach stores food, continues digestion
-Stomach wall:
Tight junctions
Mucous neck cells
Parietal cells
Chief cells
Enteroendocrine cells
Whats Ventriculus? What animal is it in?
In birds, food is stored in the crop, passed to the proventriculus (stomach with acid secretions), and then on to the ventriculus (gizzard) for further mechanical breakdown
What are the intestines for?
Small intestine longest part
For absorption of nutrients
What do an owl and sperm whale have in common?
Can only digest soft tissue. Not bones or feathers. Spit up in pellets
Where are nutrients are hydrolyzed (addition of water)?
in the lumen of the GI tract
Nutrient uptake is improved by increasing surface area in what 2 ways?
Villi and microvilli
What is the anatomy of the villi?
Enterocytes - cells of intestine
Goblet cells - produce mucus
Enteroendocrine cells - secrete hormones
Paneth cells - defense against microbes with anitbacterial molecules
What are exocrine secretions into the intestine?
Bile
Bile salts
Pancreas
What are digestive enzymes function and 4 types?
-Enzymes convert macromolecules to forms that can be absorbed and processed
Lipases- catalyzes the breakdown of fats to fatty acids and glycerol or other alcohols.
Proteases- breaks down proteins and peptides
Amylases- converts starch and glycogen into simple sugars.
Nucleases- cleaves the chains of nucleotides in nucleic acids into smaller units
Path of carbohydrate breakdown and absorption?
- *Look at diagram**slide 28
1. Broken down to smaller polysaccharides by amylase in mouth
2. Broken down by amylase in small intestine luman to disaccharides
3. Broken down by amylase in small intestine epithelium to monosaccharides
Path of protein breakdown?
- *Look at diagram**slide 29
1. Pepsin breaks down into small polypeptides in stomach
2. Trypsin and chymotrypsin break down into small polypeptides in si lumen
3. Carboxypeptidase break down intimation acids in lumen
4. Broken down to dipeptides and amino acids – by proteases in small intestine epithelium
Path of lipid breakdown?
- Digestion and import of lipids is complicated by their hydrophobicity
1. Fat broken down by bile salts to fat droplets in small intestine lumen
2. In small intestine lumen lipases breakdown fat droplets to fatty acids
Path of nucleic acid breakdown?
- Nucleases break down to nucleotides in small intestine lumen
- Nuclidases break down to nucleosides in epithelium
- Nucleosidases break down to nitrogenous base sugars in epithelium
Whats the cecum?
Herbivores, the cecum stores food material where bacteria are able to break down the cellulose
Humans- dead space
Cattle digestive tract
Ruminants – have specialized stomachs to acquire nutrients from plant material 4 compartments: Rumen Reticulum Omasum abomasum
Koala restricted diet? How does it get nutrients?
- Feed almost exclusively on one plant type (eucalyptus)
- Millions of bacteria living in their digestive tract to break it down for them, making it easier to absorb the nutrients
How do sloths obtain nutrients?
Sloths have very large, specialized, slow-acting stomachs with multiple compartments in which symbiotic bacteria break down the tough leaves
How can my dog eat long dead carp without getting sick??
Longer gut length
What 3 hormones control apetite? How?
-Three hormones control appetite by binding to receptors in the hypothalamus
Leptin (decrease), Ghrelin (increase), and Peptide YY
-Hypothalamic neurons release neurotransmitters in response to hormones from the gut
-Some neurotransmitters stimulate appetite
Neuropeptide Y (NPY)
-Some inhibit appetite
Proopriomelanocortin (POMC)
Whats the postprandial period?
Mild decrease in blood sugar after eating a big meal
What control postprandial levels of nutrients? Examples?
-Hromones control it
Ex: Insulin from beta-cells of pancreas signals muscle, fat, and liver cells in the body to absorb glucose (sugar) from the bloodstream to be used for energy.
Ex: Glucagon from alpha cells in pancreas to prevent blood glucose levels dropping too low. To do this, it acts on the liver in several ways: It stimulates the conversion of stored glycogen (stored in the liver) to glucose, which can be released into the bloodstream
Ex: Glucocorticoids (ex. Cortisol) from adrenal cortex that increase blood glucose levels, which provide readily available energy for your body cells
Whats the starvation response?
Reorganization of metabolism to ensure long-term survival
-Conserve glucose to protect glucose-dependent tissues (nervous tissues)
