Mr. Hamilton's Chapter 31: The Digestive/Urinary System, Nutrition
|Four functions of the digestive system|| 1. To break down the foods the body ingests into a form the body can use.|
2. Transfers nutrients in this form out of the digestive tract and into blood circulation.
3. To retain the waste that remains after nutrients from the food have been transferred. (What feces becomes )
4. To eliminate this waste from the body.
|central structure of the digestive system|| digestive tract: a muscular tube that passes through the body from the mouth to the anus.|
Receives input along its length from accessory digestive organs such as the gallbladder, liver, and pancreas.
|Structure of Digestive System||Begins with mouth (oral cavity) continues through pharynx, esophagus, stomach, small intestine, and large intestine. Ends at rectum and anus.|
|Digestive tract 4 layers||1. The serosa, or outermost layer.|
2. The muscularis externa, whose two sets of muscles produce the waves of contraction, called peristalsis, that move food along.
3. The submucosa, which contains blood vessels and nerve tissue that control digestion.
4. The mucosa, which absorbs digested food.
(Absorbed food is taken up by adjacent capillaries (in the case of carbohydrates and proteins) or lymphatic vessels (in the case of fats).)
|Steps of Digestion||1. Chewing in the mouth then enzymes break down carbs|
2. Food is pushed by the tongue into the pharynx (or throat) and moves by muscle contraction from there to the esophagus.
3. Peristalsis and gravity push food through the esophagus from the pharynx into the stomach.
4. The stomach digests food partly by the mechanical means of churning it and partly by chemical means.
5. Chyme (mixture of food and digestive juices) leaves the stomach.
6. Small intestine
7. Pancreas secretes digestive enzymes into small intestine which will break down fats, proteins, and carbs.
8. Gallblader, stores and concentrates bile
9. Liver controls which nutrients will be stored
10. Large intestine holds/compacts material, makes feces.
|Stomach in digestion|| Proteins = primary target|
The stomach's contents are very acidic—a quality that is valuable both for breaking food down and for killing microorganisms that come in with the food.
|Pancreas|| organ that secretes, into the small intestine, three classes of digestive enzymes that help break down fats, proteins, and carbohydrates.|
Also secretes "buffers" that raise the pH of the acidic chyme coming from the stomach.
|Gallbladder||The gallbladder stores and concentrates bile, a substance produced by the liver that aids in the digestion of fats.|
|Livers||The liver receives blood-borne nutrients from the digestive tract. It controls which nutrients will be stored and which will be sent into circulation.|
|Large Intestine|| The large intestine holds and compacts material left over from digestion, turning it into feces. |
It also returns water to general circulation and absorbs vitamins produced by resident bacteria.
Appendix is attached to the cecum. (Quiz question)
|Nutrient|| A nutrient is a substance, contained in food, that does at least one of three things: |
1. Provides energy
2. Provides a structural building block for
3. Helps regulate a process in the body
|Six classes of nutrients|| 1. water|
|Minerals||chemical elements needed by the body either to help form bodily structures or to facilitate chemical reactions.|
|Vitamins||chemical compounds that are needed in strictly small quantities to facilitate chemical reactions.|
|Calories||Proteins, carbs, and lipids provide calories required.|
Nutritional calorie = amount of energy it takes to raise the temperature of 1,000 grams of water by 1 degree Celsius.
Nutrients we consume but do not burn up end up as fat tissue.
1 gram of lipid = 9 calories of energy
1 gram of protein/carbs = 4 calories of energy
|Proteins||Composed of amino acids, provide very little energy - have many structural and regulatory functions in the body.|
Proteins --> broken down in digestive tract into amino acid building blocks --> move into circulation
20 amino acids:
11 are needed for protein synthesis, can be produced by body (Nonessential amino acids)
9 are obtained from food, cannot be produced by body (Essential amino acids)
Liver --> deaminated into urea --> eliminated by kidneys
|Three principle classes of carbohydrates|| 1. Simple sugars: monosaccharides and disacharides|
2. Starches: complex carbs that are digestible
3. Fibers: complex carbs that are indigestible
|Carbs and Nutrition|| Foods high in added simple sugars are "empty calorie foods" - calories aren't accompanied by vitamins or minerals.|
Large quantities of simple sugars = surge of glucose into blood stream.
Fresh/whole-grain complex carbs = slow, steady entry of glucose into blood stream.
|Fiber|| Fibers lower blood levels of cholesterol and reduce glycemic load. Cannot be digested.|
Whole, unrefined grains tend to be high in fiber, while processed, "white" grains have less fiber, and added simple sugars have no fiber at all.
| Oils: dietary lipids LIQUID at room temperature.|
Fats: dietary lipids SOLID at room temperature.
|Saturated fats|| Predominantly composed of saturated fatty acids.|
Trans fats and saturated fats increase the risk of heart disease.
Saturated fats normally are found in animal-based fats. Trans fats are found in a number of packaged and fast foods.
|Unsaturated fats||Predominantly composed of unsaturated fatty acids.|
Unsaturated fats rich in omega-3 fatty acids actually protect against heart disease.
Polyunsaturated and monosaturated fats are neutral with respect to heart disease.
Monounsaturated and polyunsaturated fats tend to be found in oils, while omega-3-containing unsaturated fats are found most abundantly in certain kinds of fatty fish.
|The Urinary System||Filters waste materials from the blood, regulates blood volume, conserves useful materials, such as water, nutrients, and ions.|
|Urinary System Structure|| 1. Two kidneys: produce urine.|
2. L and R ureters: urine travels through on leaving the kidneys.
3. Muscular urinary bladder: receives the urine from ureters and temporarily stores it.
4. Urethra: urine passes through from the bladder out of the body.
|Nephron|| Working unit of the kidneys, composed of nephron tubule, its associated blood vessels, and the interstitial fluid in which both are immersed.|
Nephron tubules empty into common collecting duct -->merge with other ducts --> feeds into renal pelvis --> feeds into ureter
|Urine Storage/Excretion|| Waves of muscle contraction squeeze urine out of the renal pelvis --> ureters --> temporary storage in urinary bladder|
Urethra carries the urine from urinary bladder to the exterior of the body.
Secretion of toxins/foreign materials into urine.
|How Kidneys Function||Knotted network of capillaries w/in nephron = glomerulus --> receives arterial blood --> fluid portion of blood flows out w/ small molecules (vitamins, minerals, waste products) --> Bowman's capsule --> nephron's tubule (as filtrate) --> proximal tube (original water and original nutrients are moved back into blood circulation, waste products remain in nephron tube --> collecting duct (is urine)|
|Why does alcohol ingestion increase urine output?||The alcohol suppresses ADH production.|
|Peristalsis|| Involuntary constriction and relaxation of the muscles of the intestine, pushes the contents forward. (Peristalsis and gravity push food through the esophagus, from the pharynx to the stomach.)|
Smooth muscle is involved in peristalsis in the intestine.
|Gallstones are a problem when they||block the cystic duct or common bile duct.|
|Trace minerals|| Needed in very small amounts.|
|How would blockage of the pancreatic duct affect the digestive system?||The small intestine would contain acidic, mostly undigested chyme.|
|How do fats leave the digestive system and enter the bloodstream?||in the lymphatic vessels|
|What problem might result from damage to the epiglottis?||Food would be able to enter the respiratory passageway.|
|Deficiency of which nutrient can cause muscle cramps, irregular heartbeat, or paralysis?||Potassium|
|Which of the following best describes the stomach's role in absorption?||The stomach absorbs some drugs and alcohol but few nutrients.|
|Voluntary control of urination is accomplished by||an external sphincter made of skeletal muscle.|
|Which organ is central to the body's metabolism of nutrients?||The liver|
|Movement of urine through urinary system|| 1. kidney|
3. urinary bladder
|What affect does ADH secretion have on the kidneys?||Water moves out of the kidney tubules.|
|Colon||absorbs water and vitamin K|
|Small intestine||Duodenum receives food from stomach.|
Blood carries most nutrients straight from small intestine to liver.
the pyloric sphincter regulates passage of food from stomach --> small intestine.
80% of digestive tract's absorption of nutrients takes place here, begins at the stomach and ends at the large intestine.
About 20 feet long! (Quiz question)
| Which is the main organic molecule that is digested by the secretions of the stomach?|
Digestion of which organic molecule takes a somewhat more complicated route than most nutrients?
|What is unusual about soy protein as opposed to other plant protein sources?||Soy protein has all essential amino acids in the proper proportions.|
| Folds in the stomach, allows the stomach to expand when food enters|
Finger-like projections of the mucosa, absorbs most digested food into blood