Unit D: Digestive System Flashcards
What is an Organic Compound and the Classification of Compounds?
Organic compounds are
composed of monomers (single units) which are covalently (share electrons) bonded to other monomers to form
polymers (many units).
These macromolecules (large) are classified into major categories
Organic Compounds:
- Carbohydrates
- Lipids
- Proteins
- Vitamins
- Nucleic Acids (Nucleic Acids: Found in the nucleus as part of DNA and RNA. Involved in protein synthesis)
Inorganic Compounds:
- Water
- Minerals
- Gases
What are Carbohydrates composed of? and the different forms
Composed of: C, H, O
In the ratio of: 1:2:1
Purpose:
- primary energy source of cells
- structural material (cellulose in plant cell walls)
Forms of Carbohydrates (Saccharides = sugars):
Monosaccharides (1 unit) -
- C6H12O6
- Glucose
- Galactose
- Fructose
- Same molecular formula but different structural formulas. referred to as Isomers
- Can be found in either ring or chain form
Disaccharides (2 unit) -
- C12H22O11
- Sucrose = Glu + fru (Glucose + Fructose/ White sugar)
- Lactose = Glu + Gal (Glucose - Galactose/ Milk sugar)
- Maltose = Glu + Glu (Malt sugar)
Polysaccharides (Many unit) -
- (C6H12O6)n
- Starches (plant storage, found in two forms: amylose and amylopectin)
- Cellulose (plant structure: dietary fiber)
- Glycogen (animal storage: excess sugars are joined into glycogen then stores in liver and muscles)
What are Lipids?
Composed of: C, H, O
in the Ratio: Less O than carbs
Purpose:
- energy storage (excess carbs converted to fats)
- structural component in membranes (bilipid layer)
- some hormones are lipid based
- acts as a cushion for organs and insulator against cold
- carries fat soluble vitamins (ADEK)
Fats: solid at room temp
Oils: liquid at room temp
Waxes: solid at room temp
Triacylglycerides (triglycerides) (fats)
Glycerol + 3 Fatty Acids = Fats (look at notes/slides for pics)
The fatty acids determine the type of lipid formed
What is the difference between saturated vs. unsaturated fats? what is a phospholipid
Saturated: full of hydrogen, carbon needs 4 bonds (?) all bonds are taken up. ex. animal fats
Unsaturated: carbon is double or triple-bonded, so the max amount of hydrogen I snot reached. ex. oils
Phospholipid:
- cell membrane component
What is Cholesterol?
- Found in the cell membrane
- Used to make some hormones (ie. sex hormones ex. testosterone + estrogen).
- The body obtains needed cholesterol from the fats consumed.
- Two types of cholesterol: LDL & HDL
- LDL: the “bad” cholesterol; about 70% of
cholesterol intake is in this form. - LDL can be deposited in the arteries – build up causes plaque.
- HDL: the “good” cholesterol; carry LDLs back to the liver to be broken down, hence lowering blood cholesterol levels.
- Exercise, fiber, cellulose, fish, olive oil all help to lower cholesterol levels.
What are Steroids?
- Steroids are chemicals produced by the body which act as chemical messengers, regulating cell function.
- Anabolic steroids are versions of the male sex hormone, testosterone which act to increase muscle mass
- In males steroids can result in breast enlargement, shrinking of the testes, liver and kidney dysfunction, and cancer (prostate, testicular).
What are Proteins?
Composed of: C, H, O, N (S)
Purpose:
- structural (cell membrane)
- hormones and enzymes
- movement (muscle proteins)
- antibodies and plasma proteins
note: look at amino acids in notes
What are Chemical Reactions - Metabolic Processes? + catabolic and anabolic activities
Metabolism: all chemical reactions that occur in the body
Carbohydrates (monosaccharides), proteins (amino acids), and fats (glycerol + 3 fatty acids) are broken down by digestion into their monomers. These products of digestion enter the cells of the body to be built into larger molecules (anabolism) or broken down into smaller molecules (catabolism)
Condensation Reaction or Dehydration Synthesis: Chemical reactions are ANABOLIC and bond monomers to make polymers
Hydrolysis Reaction: Chemical reactions are CATABOLIC and break polymers into simpler units
What is an Enzyme?
Enzymes are the protein catalysts that speed up the rate of reactions at low temperatures. (Reactions can occur at body temperature)
It reduces the amount of energy to run the reaction.
Thermal energy increases the rate of reactions (by increasing the movement of particles which increases the collision between particles)
What is Activation Energy?
- Enzymes decrease the activation energy (less energy required to run the reaction and occurs at a faster rate)
- Specific enzymes are used to catalyze specific reactions for each different substrate (reactant) (~200,000)
- Enzymes end in “ase”
- Ex.
Nucleases break down nucleic acids
Sucrase breaks down sucrose
Proteases break down proteins
Lipases break down lipids
Exergonic Reaction:
- Release energy
- products have less energy than reactants
- Exothermic: heat loss
What are factors that can affect Enzyme Activity?
pH:
- pH effect reaction rate of different enzymes at different pH’s
- optimum pH for each enzyme
- Enzyme pepsin works best in an acidic pH -the stomach is acidic
- Enzyme trypsin works best in a basic environment. – intestine
Substrate Concentration:
- More substrate = greater reaction rate
- @X - all enzymes activation sites are full. Reaction rate levels off
- Once reaction is complete then the enzyme are ready to deal with more substrate
Temperature:
- Optimum temp range for human enzyme - 37 C
- Note the drop off. Enzyme = proteins and they will denature or coagulate at high temps
Denature: temporary change in enzyme structure/shape when bonds are disrupted by factors such as pH and heat
Coagulate: permanent destruction of enzyme
Note: graphs are in notes/slides
What is a Metabolic Pathway?
Reactions involve several steps that are catalyzed by enzymes
- If enzyme is not present then pathway slows down or stops = no (or limited) product
- Build up of intermediary chemicals
Ex. If Enzyme B is absent what occurs to the pathway?
What is an Allosteric Activity and the different types?
Allosteric Activity: A change in an enzyme caused by the binding of a molecule
a) Feedback Inhibition: Inhibition of an enzyme in a metabolic pathway by the final product of that pathway
Slows Down or Stops Reaction
Final Product binds to regulatory site changing active site so that substrate will not be able to bond
b) Precursor Activity: The activation of the last enzyme in a metabolic pathway by the initial substrate.
Speeds up reaction
Substrate molecule combines with the regulatory site of one of the enzymes in the pathway improving the fit of the enzyme substrate complex
C) Competitive Inhibition: A molecule with a shape complementary to the specific enzyme competes with the substrate for access to the active site on the enzyme and blocks the chemical reaction.
Substrate cannot bind
What is Cell Homeostasis?
Homeostasis: “Steady State”; metabolic activities of an organism directed toward maintaining steady conditions
Feedback Systems: self-regulating systems using hormones or the nervous system to transmit messages
a) Receptors (Sensors): detect changes in internal and external environment
b) Control Centre (Brain): analyzes, interprets and determines appropriate response
c) Effectors (Glands & Muscles): carry out actions
Positive Feedback: Homeostatic processes that causes movement away from the normal state “A produces more of B which in turn produces more of A”.
Ex. Release of prostaglandins during child labour to continue contractions
Blood Clotting: injured tissue signals chemicals attract platelets which release
chemicals to activate more platelets to form a clot
Negative Feedback:
Homeostatic processes that causes movement back to normal “A slows down or prevents production of B”
What are the components of digestion?
Ingestion: Taking in nutrients
Digestion: Breakdown of complex molecules into smaller units
Absorption: Monomers of chemical enter the blood stream or body cells
Egestion: Removal of food waste (non digested and excess materials)
Nutrients: source of chemicals (building blocks) for growth, repair, reproduction and energy
What are the 2 types of digestion?
Physical Digestion: Mechanical breakdown of large particles into smaller pieces; - increases surface area for activity of enzymes
Chemical Digestion: (physical reaction = no new chemical produced) Activity of enzymes chemically alters the food (chemical change) ex. proteins changed to amino acids
The oral cavity
Ingestion, Physical and chemical digestion occurs
Teeth (mastication = chewing):
a) Incisors - cutting
b) Canines - tearing
c) Molars - grinding
Taste Buds:
- Sweet
- Sour
- Salty
- Bitter
- Umami (savoury)
Salivary glands
Secretes saliva or salivary juices which contains water and salivary amylase
- Salivary amylase initiates chemical digestion of carbohydrates. Amylose units are broken down into disaccharides
- Mucous lubricates and binds food forming a bolus
- Forms a solution so that chemicals can enter the taste buds = sense of taste
Esophagus
Flexible tube that moves food to the
stomach through peristalsis
Swallowing: soft palate closes the nasal cavity and epiglottis closes the trachea, tongue pushes food to the back of mouth
Peristalsis: the involuntary rhythmic movement of the smooth muscles that line the digestive tract.
Stomach
- J shaped organ with two sphincters (LES – Lower esophageal sphincter and pyloric sphincter) which control rate of food passage
- 3 layers of muscle that churn food (circular, longitudinal and diagonal smooth muscles)
- Rugae: folds of the inner layer that allow for expansion
- 1 to 1.5 liter capacity
- Rate of fluid emptying determined by fluidity of chyme
Function:
Produces gastric juices and starts
protein digestion
Eructation (burping) – removes most of swallowed air in stomach
Gastric Juices - Chemicals produced by the stomach
Gastrin (hormone):
- Activated by the presence of food in the stomach
- Produced by cells in stomach lining and travels through blood and stimulates other stomach cells to secrete gastric juices
HCl (aq):
- Kills pathogens
- Activates pepsinogen
(Parietal Cells)
Pepsinogen (Chief Cells):
- Pepsinogen activated to Pepsin in the presence of HCl (aq)
- Breaks down protein polymers into smaller chains
Mucin:
- Thick mucous lining that protects stomach lining against HCl(aq)
Rennin (Chymosin):
- Milk clotting – keeps milk protein, casein, in stomach longer so enzymes can act on it
Enzymes travel through a “duct” (tube)
Hormones travel through the blood
Both from site of production to
site of activity
Small Intestine
Function:
1. Final digestion of chemicals
2. Primary site of absorption
- 3 sections: duodenum, jejunum, ileum
- Mesentery: attaches intestine to abdominal wall, provides support and contains blood vessels, lymph vessels and nerves
- Length of S.I. Related to diet (Carnivores = short, herbivores = long), 6-7 m long
- Secretes Intestinal Juices
- Digestion of lipids and final digestion of carbohydrates and proteins
- weak peristalsis (3 – 6 hrs)
What are the structural adaptions of the small intestine?
Structural Adaptations of Small Intestine 🡪 promotes absorption of nutrients by increasing surface area
Villi: fingerlike projections inside the small intestine
Microvilli: fingerlike projections on the outer edge of the small intestine tissues
Lacteals: Lymph vessels inside of villi. They absorb glycerol and fatty acids which will then be transported into the circulatory system
Capillary network: Monosaccharides and Amino Acids are absorbed\ into the bloodstream (by diffusion or active transport)
What are the chemicals that act within the lumen of the small intestine?
Prosecretin (Small Intestine): Acid from stomach converts Prosecretin to secretin travels to Pancreas. Pancreas releases bicarbonate ion
Cholecystokinin/CCK (Small Intestine): Fatty foods cause release of CCK. Travels to liver/gall bladder to release bile
Erepsin (Pancreas & Small Intestine): Peptides + H20 🡪 amino acids
Disaccharidases (Small Intestine): Maltase = Maltose + H20 🡪 glucose
Sucrase = sucrose + H20 🡪 glucose + fructose
Lactase = lactose + H20 🡪 glucose + galactose
Trypsinogen (Pancreas): Trypsinogen activated by Enterokinase to
Trypsin Protein + H20 🡪 peptides
Enterokinase (Small Intestine): Activates trypsinogen to change to trypsin
Amylase (Pancreas): Starch + H20 🡪 maltose
Bicarbonate Ion (Pancreas): Neutralizes acidic chyme
Lipase (Pancreas): Breaks down lipids into glycerol & 3 fatty
acids
Bile (Liver): Emulsifies Fat
Enterogastrone (Small Intestine): Slows down rate of stomach emptying so fats stay in intestine longer
