Chapter 21: Nutrition and Digestion Flashcards
What is a calorie
Describes the potential energy of food; a measure of how much cellular work can be powered by the energy released from breaking down foods.
Macronutrients and micronutrients
Macronutrients are nutrients that our body requires in large amounts:
* Carbohydrate
* Proteins
* Fats
Micronutrients required in small amounts:
* Vitamins
* Mineral
Explain the glycemic index (GI), and the type of information it provides
A scale that ranks a carbohydrate-containing food or drink by how much it raises blood sugar levels after it is eaten or drank; differentiates between high GI foods (quickly digested and converted to blood sugar) and low GI foods (digestes more slowly → slower rise in blood sugar).
Undernourished and malnourished
Deficient in one or more essential nutrients = malnourished.
Deficient in calories = undernourished.
What is the difference in function between HDL and LDL cholesterol?
Both are types of dietary cholesterol. Low-density lipoprotein delivers cholesterol to cells; correlated with blocked blood vessels, high blood pressure etc. High-density lipoprotein brings excess cholesterol from blood to liver for recycling; may decrease vessel blockage
What are essential nutrients and different classes?
nutrients that can’t be made by animal and must be supplied through diet:
1. Essential amino acids
1. Essential fatty acids
1. Minerals
1. Vitamins
Vitamins and minerals, functions
An organic compound essential for body funtion:
* Required in small amoutns
* Humans don’t have enzymes to make most vitamins
* Most function as coenzymes that assist metabolic reactions
Inorganic elements essential for body function:
* Required in different amounts
Fat-soluble and water-soluble vitamin and its function
Fat-soluble vitamins are absorbed along with fats in our diet and stored in body’s fatty tissues and liver:
* Vitamin D increases absorption of calcium in small intestine
Vitamin C (water-soluble)
* Required for collagen synthesis
Minerals and functions
- Iron (Fe) is the oxygen-binding component of hemoglobin.
- Calcium (Ca) and phosphorus (P) are components of bone tissue.
- Magnesium (Mg) support enzyme function.
- Sodium (Na), potassium (K), and calcium are important for nerve and muscle activity.
Why and in what situation do fat-soluble vitamins present a greater toxicity risk than water-soluble vitamins?
Excess fat-soluble vitamins are stored in liver, spleen, and adipose tissue, which could lead to toxicity if ingested in improper amounts from supplements. Excess water-soluble vitamins are eleminated in urine.
Give 2 reason why water is important part of our diet
- Carries nutrients to your cells
- Required for cellular metabolism
- Provides moist environment for ear, nose, and throat
- Allows kidneys to expel toxins and wastes
- Prevents kidney stones and constipation
- Improves digestion
- Helps maintain a healthy weight
obesity and possible causes
Excessive accumulation of fat that has a negative impact on health.
Could be due to issues that involve genetics and lifestyle factors:
- Mutations in leptin, a hormone produced by adipose cells to suppress appetite
- Diet of red meat, sweets, processed foods
Why do organisms have to eat? :(
- Animals eat to obtain energy for body activities, which can be stored as ATP.
- Obtain building blocks to assemble new molecules
- Obtain essential nutrients (e.g. vitamins and minerals) that can’t be synthesized
What is a healthy diet? :/
One that must contain:
* Fuel
* Raw materials
* Essential nutrients
(Aerobic) cellular respiration (number of ATP produced, oxygen requirement, and by-products)
*Preferred by cells, but requires O2.
3 stages:
1. Glycolysis (makes 2 ATP)
2. Citric acid cycle (2)
3. Oxydative phosphyration (28)
32 ATP per glucose molecule consumed.
CO2 and H20 as waste products
Draw out reaction
Fermentation (anaerobic) (number of ATP produced, oxygen requirement, and by-products
Done when oxygen isn’t available.
2 steps:
1. Glycolysis
2. Fermentation (lactic acid or alcohol)
Lactic acid fermentation:
Glucose converted to lactate.
Alcohol fermentation:
Glucose converted to CO2 and ethanol
2 ATP per glucose molecule consumed.
CO2, lactic acid, and alcohol as waste products.
The 4 stages of food processing and where they occur in the
human body.
- Ingestion: . . . eating.
- Digestion: breaking down (chemical and mechanical) food into molecules small enough for the body to absorb.
- Absorption: taking up products of digestion, usually by cells lining the digestive tract.
- Elimination: removing undigested materials from digestive tract.
Difference between mechanical and chemical digestion
Mechanical: physically breaking down food substances into smaller particles to more efficiently undergo chemical digestion.
Chemical digestion: process by which macromolecules are split into their components
* Requires enzymes that catalyze the hydrolysis of covalent bonds.
Identify digestive organs and compartments in animals that are not present in the human digestive tract and briefly describe their functions
Simple animals: gastrovascular cavity (single sac with 1 opening)
Humans: alimentary canal (tube that run between 2 openings).
Some animals also have specialized compartments that aren’t present in humans:
* Crop: pouch that softens and stores food
* Gizzard: grinds up food
Oral cavity: teeth, salivary glands, tongue functions
Teeth (incisors, canines, molars) break up food.
Salivary glands produce saliva:
* Moistens and lubricates food
* Buffers neutralize acids
* Antimicrobial agents
* Salivary amylase begins hydrolysis of starch
Tongue pushes the chewed food (bolus) into the pharynx.
Pharynx: epiglottis
Covers the opening to the trachea and prevents entry of food into airways during swallowing
Esophagus
Esophagus transports food to the stomach
* Peristalsis: smooth (involuntary) muscles contract to move bolus through the alimentary canal.
stomach, gastric juice
- Located under the diaphragm
- Stretches to store food
- mechanical and chemical digestion:
Bolus mixed with gastric juice to form chyme.
Secretes gastric juice containing:
* Mucus (secreted by mucous cells): protects stomach.
* HCL (pH 2, secreted by parietal cells): kills bacteria and denatures protein (which increases SA for enzymes to act on).
* Pepsin (secreted by chief cells as pepsinogen): stomach enzyme that breaks covalent bonds between amino acids - protein → peptides.
small intestines, sections, epithelium
- Major organ for chemical digestion and nutrient absorption.
- Non-ciliated simple columnar epithelium lining the small intestine synthesize digestive enzymes (maltase, sucrase, lactase, peptidases etc.).
Duodenum
* Mixes chyme with secretions from pancreas and liver.
Jejunum
* Continues chemical digestion and nutrient absorption
Ileum
* Nutrient absorption
Large intestines. large intestinal bacteria
Water absorption.
Feces (undigested materials (e.g. cellulose) + bile salts + bacteria) passes to.
Large intestinal bacteria produce:
* Vitamin K
* Folic acid
* B vitamins
Rectum and anus
Rectum: a muscular organ at end of large intestine; stores feces.
Anus: consists of internal (involuntary) and external (voluntary) sphincters.
Acessory organs: pancreas
Pancreas produces alkaline solution (neutralizes acidic chyme) and digestive enzyme (pancreatic amylase, trypsin, pancreatic lipase, chymotrypsin, nucleases).
Acessory organs: liver
Liver: Produces bile, which is then stored in gallbladder.
* Bile emulsifies fats (large fat droplets → smaller droplets; increase SA for pancreatic lipase to act on)
Sphincters
Layers of muscle that constrict to regulate food from one location in the digestive tract to another.
In 5 locations:
Esophageal sphincter relaxes (opens) to allow bolus into esophagus.
Cardiac sphincter (lower esophageal sphincter) regulates the passage of food from the esophagus into the stomach.
Pyloric sphincter:through which chyme passes to enter small intestines.
Microbial causes of gastric ulcers
Gastric ulcers are open sores in stomach lining.
* Bacterium can infect stomach lining - protective mucus erods and lining is damaged.
Trace the digestion of carbohydrates, the locations where each process occurs, and the chemicals responsible for catabolism
Digestion of carbs starts in mouth and ends in small intestines.
Mouth: salivary amylase (starch → maltose) Small intestine: pancreatic amylase (polysaccharide → maltose), maltase (maltose → glucose).
Trace the digestion of protein, the locations where each process occurs, and the chemicals responsible for catabolism
Starts in stomach and ends in small intestine.
Stomach: pepsin (polypeptide chains → smaller polypeptides)
Small intestines: trypsin, chymotrypsin (→ smaller polypeptides), peptidases (→ amino acids).
Trace the digestion of fat, the locations where each process occurs, and the chemicals responsible for catabolism
Small intestine: bile emulsifies fat (fat globules → fat droplets), lipase ( → fatty acids + glycerol).
