Digestive System Flashcards
Water in the human body
Main fluid compartment of:
- intracellular fluid (inside cell)
- extracellular fluid (outside cell)
- intersitial fluid (between cells)
Functions:
1. transport dissolved nutrients
2. remove waste from cells
3. lubricate tissues and joints
4. main component of essential body fluids
5. regulate body temperature (sweat)
6. eliminate waste (urine and sweat)
Minerals
Inorganic substances that enable chemical reactions and aid in tissue development, growth, and immunity
Ex. calcium, iron, magnesium, potassium, sodium
Vitamins
Organic substances that enable chemical reactions and aid in tisse development, growth, and immunity
Ex. A (carotene), B (thiamene), C (ascorbic acid), D, E
What is dissolved in the fluid of a cell?
- Inorganic molecules and ions
- small and simple
- water, phosphate, H, Na - Organic molecules
- macromolecules
- made up of C and H (N, O, etc.)
- called nutrients
Nutrients
Organic molecules used for energy, repair/building, regulating cell activity
The 4 Types of Macromolecules
- Carbohydrates
- Lipids (fats)
- Protein
- Nucleic acids
Essential nutrients
What the body cannot create, and must therefore be consumed in the diet (not nucleic acid)
Provide energy to maintain body’s metabolism (mostly carbohydrates and lipids)
Carbohydrates
Contain elements C, H2, O2
Provide short and long term energy storage
1. Simple sugars (mono- and di- saccharides)
2. Polysaccharides
Simple sugars
- Monosaccharides
- 6 carbons long
- GLUCOSE, FRUCTOSE, GALACTOSE - Disaccharides
- made of two monosaccharides
- SUCROSE, MALTOSE, LACTOSE
Polysaccharides
Complex carbs
- many monosaccharides linked together
- long term energy storage (liver)
- STARCH (plants), CELLULOSE (pants), GLYCOGEN (animals)
Lipids
Fats are a type of lipid
Insoluble in water
Contain, C, H2, O2
BUTTER, LARD, OIL
Proteins
Assembled from small sub-units - amino acids
Amino acids are joined by peptide bonds
20 amino acids (8 essential, 12 non-essential)
Chains of amino acids are called polypeptides
Most enzymes and some hormones (e.g. insulin) are proteins
Build/repair, catalyze reactions (enzymes), fight infection (antibodies), messengers (hormones)
How do animals obtain food?
They are heterotrophs
1. Filter Feeders
2. Substrate feeders
3. Fluid Feeders
4. Bulk (Chunk) Feeders
Filter Feeders
Aquatic animals that filter food into their mouths and then filters it to smaller organisms to digest
Ex. tube worms, clams, whales, tube sponges
Substrate Feeders
Live on or in their food source, eating their way through it
Ex. caterpillars, earthworms
Fluid Feeders
Special mouthparts adapted for piercing and sucking
Some obtain nutrient rich fluids from plants
Ex. mosquitoes, ticks, spiders, hummingbird
Bulk (Chunk) Feeders
Ingest large pieces of food
Ex. animals, most vertibrates
Stages of food processing
- Ingestion
- Digestion
- Absorption
- Elimination (egestion)
Ingestion
The taking in or eating of food
Digestion
Breakdown of food by mechanical and chemical means into small molecules
Absorption
Occurs in the small intestine
Transportation of the products of digestion from the digestive system into the circulatory system, which distributes them to the rest of the body
Elimination (egestion)
The removal of undigested solid waste matter from the body
Types of Digestion
- Mechanical: physical breakdown of the food into smaller bits. Use of teeth
- Chemical: breakdown of nutrient molecules into smaller molecules. Use of enzymes
How long does it take for food to go through the digestive system?
24-36 hours
Mouth (oral cavity)
Opening for food, equipped with teeth and tongue
Food enters in a process called ingestion
Teeth
Arranged in the upper and lower jaws
Initiate the physical breakdown of food
Incisors - cut
Bicuspids and canines - tearing and piercing
Molars - grinding
Uvula
Hangs from the middle of the back edge of the soft palate
Prevents food from entering the nose
Salivary Glands
A group of cell (tissue) simulated by the action of chewing
Submandibular, parotid, and sublingual
Manufacture and secrete saliva (mixture of water, mucous, and amylase)
Tongue
Muscular organ covered with tiny papillae that house the taste buds
Moves food around for thorough chewing and mixing with saliva until it forms a bolus (partially digested food)
Pushes bolus back into the pharynx
Bolus
Partially digested food
Pharynx
Throat region
Dual purpose tract receives air and food
Epiglottis
Flap like tissue
Covers the trachea to ensure food is passed to the esophagus
Esophagus
Long muscular tube
Carries the bolus by action of two muscle layers (circular and longitudinal) located along its length
Muscles contract creating a rhythmic wavelike motion called peristalsis, which pushes the bolus down into the stomach
Peristalsis
Wavelike motion created by the contraction and relaxation of circular and longitudinal muscles along the digestive tract
Stomach
Muscular J-shaped bag-like organ
Interior lined with gastric glands
Cardiac and pylonic sphincter - rings of muscle that control the flow of food entering and leaving the stomach
3 muscle layers arranged in circular, longitudinal and oblique patterns that work to mix up the contents of the stomach with gastric juices (enzymes, mucous, hydrochloric acid - acidic, kills bacteria)
Chyme leaves the stomach
What controls the flow of food into and out of the stomach?
Cardiac and pylonic sphincter
Chyme
Partially digested food leaving the stomach
Pancreas
Glandular (gland) organ located deep in the abdomen
Produces several digestive secretions - fat, protein and carbohydrate-digesting enzymes and a neutralizer (sodium bicarbonate) that are carried to the intestines via the pancreatic duct
Liver
Largest gland
Produces bile (stored in the gall bladder) - emulsifying agent for digestion of fats
Emulsion
The fat is broken up into small particles
Small Intestine
Long muscular tube (6.2m long, 2.5cm wide)
Composed of 3 segments:
1. Deodenum: shortest but widest
2. Jejunum: many folds
3. Ileum: longest
Coated with thick mucus to protect from the acidic chyme
Moves chyme by peristalsis
Continues to chemically break down food from secretions by the pancreas and liver
Absorbs nutrients into the blood through villi
Villi
Small fingure-like projections that absorb nutrients into the bloodstream
Increase absorbative surface
Large Intestine (colon)
Large tube (1.5m long)
Composed of the calcum, colon (ascending, transverse, descending), rectum (last segment), and anus
Indigestible food matter (i.e. water, micronutrients, vitamin B, K produced by bacteria) remains after absorption
It compacts into feces (living, dead bactera, cellulose, water)
Anus
Anal canal that starts at the bottom of the rectum and is the last portion of the large intestine
Feces pass here in egestion, achieved by peristalsis of the rectum and relaxation of the anal sphincter muscles
When rectum is full, internal sphincter relaxes, external sphincter awaits voluntary relaxation
Enzymes
Catalysts found in living things that speed up the rate of a reaction
Characteristics of enzymes
They are very specific to a substrate (molecule)
Unchanged when reaction is over
Do not cause the reaction
Reusable
Need specific conditions
How are macromolecules broken down?
Hydrolysis: the chemical reaction in which water breaks apart macromolecules into smaller molecules with the help of enzymes
Saliva
Location: salivary glands, oral cavity (37C)
Enzyme: amylase
Substrate: starch
Products: maltose
Gastric Juice
Location: stomach (acidic)
Enzyme: pepsin
Substrate: proteins
Product: smaller polypeptides
Bile Juice
Location: liver, small intestine (duodenum) (alkaline)
Enzyme: bile
Substrate: fats
Product: smaller fat globules
Pancreatic Juices
Location: pancreas, small intestine (slightly basic)
Enzyme: lipase
Substrate: small fat
Product: glycerol and fatty acids
Enzyme: amylase
Substrate: starch
Product: smaller maltose
Enzyme: chymotrypsin, carboxypeptidase, trypsin
Substrate: small proteins
Product: peptides
Intestinal Juice
Location: small intestine
Enzyme: sucrase
Substrate: sucrose
Product: glucose and fructose
Enzyme: maltase
Substrate: maltose
Product: glucose
Enzyme: lactase
Substrate: lactose
Product: glucose and galactose
Enzyme: peptidase, aminopeptidase, tripeptidase, trypsin
Substrate: small proteins
Product: amino acids
Kwashiorkor
Nutritional disorder caused by a lack of protein in the diet
More common in third world countries
Symptoms: slowed growth, diarrhea, permanent underdevelopment of the brain, distended abdomen
Anorexia nervosa
Fatal eating disorder characterized by the relentless pursuit of thinness
Bulimia
Eating disorder characterized by gorging and purging (forced vomiting)
Anemia
A deficiency (lack of something) in one’s diet
Ex. iron deficiency
Hiatus Hernia
Structural and inflammatory disorder that can be controlled by on’es diet
Occurs when there is a gap between the esophagus and the opening of the diaphragm
Symptoms: heartburn, pain
Ulcers
When the stomach lining is being eaten away by the acid in the stomach
Phenylketonuria (PKU)
Children that inherit that fatal metabolic disorder are missing an enzyme that is found in the lysosomes of cells
Tay-Sachs
Metabolic digestive disorder resulting from poisoning through the accumulation of completely digested food components
Missing an important enzyme
Acute Appendicitis
Common inflammatory disorder caused by obstruction and characterized by abdominal pain and corrected by the removal of the appendix
Osteoporosis
Condition in which the bones become increasingly brittle (break) because of a loss of calcium
Ricketts
Dificiency disease that affects the bones of infants and children caused by a lack of Vitamin D and sunlight
Diabetes
When the body does not make enough insulin or can’t use it as well as it should
Crohn’s Disease
Inflammatory bowel disease causing swelling of the tissue in the digestive tract
