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BPK 110 > Chapter 3: Digestion, Absorption and Metabolism > Flashcards

Chapter 3: Digestion, Absorption and Metabolism Flashcards

1
Q

define: metabolism

A
  • sum of all chemical reactions in the body
  • Metabolism of nutrients: cellular respiration; captures all the energy in sugars, triglycerides and amino acids into ATP
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2
Q

digestion

- describe 2 types

A
  • Process that separates nutrients in food and breaks larger molecules into smaller ones
  • Mechanical digestion: teeth chewing, stomach churning
  • Chemical digestion: uses enzymes to alter the chemical structure of nutrients and reduces them to their building blocks
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3
Q

enzymes

A

Speed up reactions and provides location for chemical reactions to occur

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4
Q

hydrolysis

A

The input of water breaks down the molecule

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5
Q

condensation

A

Combines molecules by liberating a water molecule

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6
Q

hormones

A

Chemical messengers required for many physiological processes

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7
Q

sphincters

A

Circular muscles that contract to close openings and relaxes to open them

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8
Q

What are some things that impact digestive transit times. What is the average digestive time?

A
  • Age, activity levels, diet, gender, medication, infection, emotional state
  • ~2 days for food to pass through the entire tract
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9
Q

List all the layers of the digestive tract wall (5)

A
  • lumen
  • mucosa
  • submucosa
  • muscularis
  • serosa
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10
Q

describe the following layer of the digestive tract wall: lumen and mucosa

A
  • lumen: inner cavity of the small intestine tube
  • mucosa: layer that secretes mucus, keeps digestive tract moist, and protects it from infection, plays a role in absorption
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11
Q

describe the following layer of the digestive tract wall: submucosa

A
  • Submucosa: connects mucosa to the more superficial muscularis layer, blood vessels, lymphatic vessels, and nerves are found here
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12
Q

describe the following layer of the digestive tract wall: muscularis

A
  • Muscularis: composed of smooth muscles that are autonomic; pushes food forward and helps it mix with digestive secretions
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13
Q

describe the following layer of the digestive tract wall: serosa

A
  • Serosa: outermost layer that consists of a layer of connective tissue; helps to reduce friction with organs or helps anchor tract in place
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14
Q

explain the enteric nervous system

A
  • Various nerves and nerve plexuses that create a system
  • 500 million neurons arranged in groupings called a nerve plexeus
  • all in the lining of the gastrointestinal system
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15
Q

mouth

  • chemical digestion
  • manual digestion
  • define bolus
A
  • chem. digestion: saliva - from 3 main glands (parotid, submandibular, sublingual)
  • 2 enzymes: salivary amylase becomes amylose (starch); lingual lipase (lipids)
  • manual digestion: tongue and teeth
  • bolus: uniform cohesive structure created through chewing and saliva
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16
Q

pharynx

  • role
  • define: epiglottis
A
  • Passageway for both food and air

- Epiglottis; flap of tissue that covers trachea opening when we swallow so food goes down the esophagus

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17
Q

esophagus

- role

A
  • Passageway for food from pharynx to stomach; Food enters stomach with the lower esophageal sphincter opens
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18
Q

how does food move through the digestive tract?

A
  • Peristalsis: smooth muscle contractions to move bolus further through the digestion tract
  • Gravity helps too
  • NOT segmentation
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19
Q

stomach

  • how long does food remain in the stomach
  • what is chemically digested here
  • mechanical digestion
  • types of muscle (3)
  • define chyme
  • pyloric sphincter
  • crypts
A
  • 4-5 hours before it empties
  • chemical digestion of protein begins; Partial absorption of water and amino acids occur here
  • mechanical digestion: diagonal smooth muscle allows for churning to facilitate chemical digestion
  • types of muscle: longitudinal, circular, diagonal
  • chyme: bolus turns into semiliquid substance
  • pyloric sphincter: opens to let chyme enter the small intestine
  • crypts: invaginations in the stomach that increase surface area, allowing more stomach cells to be involved in digestion
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20
Q

gastric juices (4)

A
  • Mucus: lubrication and a medium for chemical reactions to occur in; lines the stomach’s inner wall protecting it from stomach acid and juices
  • Hydrochloric acid (HCl): unravels proteins, exposing sites where enzymes can further break them down; plays a role in activating pepsin
  • Pepsinogen: proenzyme; HCl converts pepsinogen into pepsin; Pepsin: breaks down amino acid chains into smaller chains
  • Gastric lipase: breaks down lipids
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21
Q

small intestine

  • describe the structure
  • villi
  • microvilli
  • enterocytes
  • capillary beds
  • lacteal
  • peristalsis and segmentation
A

structure

  • 6m in length
  • duodenum, jejunum, ileum
  • large folds that face the lumen (increase SA and slow the passage of food along its path)
  • villi
  • microvilli: tiny projections in the enterocytes; make up the brush border; where digestive enzymes are stored (lactase, sucrase, maltase)
  • enterocytes: small intestine cells that line the peaks and valleys of the villus surface
  • Capillary beds exist within the submucosa of the villi; all nutrients are absorbed here except for large lipids and fat soluble vitamins
  • Lacteal: lymphatic vessels that absorb large lipids and fat soluble vitamins; enter the blood by draining through the thoracic duct
  • segmentation: movement that breaks material into smaller components while mixing it with digestive juices
22
Q

absorption in the small intestine

  • osmosis
  • simple diffusion
  • facilitated diffusion
  • active transportation
A
  • Osmosis: movement of water in response to concentration differences
  • Simple diffusion: fatty acids and fat soluble vitamins; absorbed along the spaces between phospholipids in the enterocyte cell membrane; do not require a transporter
  • Facilitated diffusion: a protein transporter acts as tunnels to allow material to pass from an area of high concentration to low concentration; Certain sugars require this (fructose)
  • Active transportation: glucose and amino acids move from an area of low concentration to high concentration; requires energy and a protein transporter to move against the concentration grain
23
Q

List the accessory organs

A
  • pancreas
  • gallbladder
  • liver
24
Q

pancreas

  • 2 functions
  • list the enzymes (4)
A
  • Regulates blood glucose using hormones (endocrine function)
  • Insulin: when glucose rises tells body to store sugar
  • Glucagon: tells liver to release stored sugar when glucose drops
  • Releases pancreatic juices (exocrine function) that contain digestive enzymes into the small intestine
  • Protease: protein digestion
  • Lipase: lipid digestion
  • Amylase: carbohydrate digestion
  • Bicarbonate: buffer that reduces acidity of chyme, increasing the effectiveness of digestion in small intestine
25
Q

Liver and gallbladder

  • emulsification
  • micelle
A
  • The liver produces bile which promotes lipid digestion
  • Gallbladder stores bile; secretes it when needed
  • Emulsification: suspension of lipids to be easily transported within the small intestine’s lumen
  • Micelle: grouped lipids within a ring of bile salts
26
Q

summarize the chemical digestion that occurs in the small intestine for

  • carbs
  • proteins
  • lipids
A
  • see google doc
27
Q

large intestine

  • list the parts
  • mechanical digestion
  • rectum
A
  • 1.5m in length but with a larger diameter than the small i
  • ileum from small intestine
  • -> cecum: first part of the large intetine
  • appendix: hangs from the cecum; plays a role in microbiome composition
  • cecum –> ascending, transverse, descending, and sigmoid colons (collectively known as the colon)
  • mechanical digestion: peristalsis and segmentation
  • rectum: where feces is held until it is ready to be excreted
28
Q

microbiome

  • define
  • microbiota
  • explain role
A
  • genetic material of the non human organisms found in our body
  • microbiota: all the non-human organisms found in our body
  • Play a role in vitamin synthesis, energy harvesting, health/disease, appetite
  • Fermentation of unused carbohydrates and production of short-chain fatty acids (energy harvesting)
  • Promote healthy population of intesntinal cells
  • Prevent allergies
  • Prevent IBD
  • Suppress growth of harmful bacteria
29
Q

probiotics

  • define
  • found in?
  • impact
A
  • Cultures of living organisms, typically bacteria
  • Found in: some supplements, yogurt, kombucha
  • Need to be taken for a month+ for effects to be evident: Antibiotic associated diarrhea, traveller’s diarrhea, acute respiratory infections, infant colic, type of colitis; Ongoing research on effect of IBS, obesity, cardiovascular disease, cancer
30
Q

prebiotics

A
  • Act as food for the microbiome and support its function
  • Medium length carbs that our gut microbes ferment
  • Sources: asparagus, beet sugar, onion, wheat, honey, banana, barley, tomato, rye, soymilk, peas, beans, and seaweed
31
Q

ulcers

  • what
  • how
  • 2 types
A
  • Open sores that can occur along the lining of a body structure
  • Caused by a weakening of mucosal layer of the digestive tract wall
  • Canker sores: ulcer in the mouth; caused by biting the cheek, eating a lot of acidic food, burning the inside of the mouth
  • Peptic ulcers: occur in the esophagus, stomach, or small intestine; related to H. pylori bacteria infection
32
Q

Gastroesophageal reflux disease aka acid reflux

  • what
  • treatments
  • what can it lead to
A
  • Weakening of the lower esophageal sphincter that allows stomach acid to spill upward into the esophagus
  • Weight loss improves acid levels and symptoms of acid reflux
  • Elevating the head of the bed reduces reflux
  • Decreasing tobacco, alcohol, chocolate, large meals, spicy foods, high fat meals reduce symptoms
  • Can lead to the narrowing of the esophagus and promote esophageal ulcers
33
Q

Irritable bowel syndrome (IBS)

A
  • Illness that impacts the large intestine, symptoms include abdominal pain, bloating, cramping, diarrhea, constipation, flatulence
  • Cause: muscular and nervous system impairment, inflammation, infection, gender (being a woman), family history can all increase risk
  • Changes in the microbiota may promote and aggravate symptoms
34
Q

Diverticulitis

  • define
  • diverticula
  • bleeding diverticula
  • what can increase your risk to get diverticulitis
A
  • diverticula: weakened walls of the large intestine form outpouching
  • Inflamed diverticula= diverticulitis
  • Bleeding diverticula= diverticulosis
  • Age, obesity, smoking, physical inactivity, low fibre high animal fat diet can increase risk
35
Q

gallstones

  • define
  • how can it occur
  • risk factors
A
  • Hardened bile deposits that accumulate in the gallbladder or bile duct; can cause pain when fat is consumed and the gallbladder contracts to release bile
  • Occur due to an overabundance of cholesterol
  • Risk factors: gender (women), estrogen-containing contraceptives, obesity, rapid weight loss, physical inactivity
36
Q

Colorectal cancer

A
  • Physical activity and obesity increase risk
  • Diets high in red and processed meats increase risk
  • Diets high in vegetables, fruits, and fibre decrease risk
37
Q

constipation

A
  • Difficult to pass or less frequent bowel movements
  • Increases risk for hemorrhoids
  • Stools are hard and dry, can be painful to excrete
  • Risk factors: age, female sex, genetics, physical inactivity, IBS, use of certain medications
  • Diets low in fruits, vegetables and water increase risk
38
Q

diarrhea

A
  • When matter passes too quickly through large intestine
  • Stools are loose and have a liquid like consistency
  • Typically due to bacterial and viral infections; body tries to pass bacteria or viruses out of body quickly
39
Q

Food allergies

A

Immune system reacts to non harmful antigens called allergens

  • First exposure: begins the process with the production of antibodies
  • Second: allergens bind to antibodies and cause release of histamine
  • Symptoms: redness, swelling, hives, tingling on tongue/lips, difficulty breathing, decreased blood pressure
  • Extreme cases lead to anaphylaxis
40
Q

celiac disease

A
  • Inherited disease
  • Gluten protein triggers an immune response which damages villi
  • Symptoms and complications: abdominal pain, diarrhea, fatigue, malnutrition, weight loss, anemia, osteoporosis, intestinal cancer
  • Treatment: avoid gluten all together
41
Q

liver

A
  • Nutrients absorbed in the small intestine enter hepatic portal vein that lead to the liver
  • Acts as a gatekeeper for nutrients: use them, store them, send them to the rest of the body, detoxify them
  • Can store glucose → glycogen
  • Whatever isn’t used here is sent to the rest of the body through the bloodstream
42
Q

lymphatic system

  • what
  • 3 functions
A
  • Network of lymph vessels that contain infection fighting cells
    3 functions
  • Clears tissues of excess fluid
    Immune response is launched when an antigen is detected in the lymph
  • Large lipids and water insoluble materials are absorbed into the lymph
  • Lymph then drains into CVS cvs via the thoracic duct
43
Q

anabolism

A
  • Smaller molecules coming together to make large ones
  • Require added energy
  • Example: protein synthesis
44
Q

catabolism

A
  • Large molecules being broken down into smaller ones

- Process gives off energy

45
Q

cellular respiration

  • metabolic pathway
  • location it occurs
  • formula
  • metabolic pathway
A
  • catabolic process that leads to the capture of released energy within ATP
  • occurs in the mitochondria
  • see doc
  • Metabolic pathway: steps that create ATP
46
Q

glucose metabolism

A
  • see google doc
47
Q

lipid metabolism

A
  • see google doc
48
Q

ketogenesis

A
  • Occurs when diet is high in fat and very low in carbohydrates
  • Citric acid cycle requires carbohydrates
  • On a low carb diet, fatty acids cannot enter citric acid cycle, instead form ketones
49
Q

amino acid metabolism

A
  • see google doc
50
Q

Non energy uses of sugars lipids and amino acids

A

Most of the excess is stored as lipid in our fat tissue

51
Q

Synthesizing new molecules

A
  • Energy yielding nutrients that are not used for energy are used to form other molecules (requires ATP)

Glucose:

  • Forms glycogen
  • Small energy reserve in the muscle/liver
  • Forms fatty acids, stored in fat tissue

Fatty acids:

  • Stored in fat tissue
  • May also be used to help form cell membranes, regulatory molecules

Amino acids:

  • Used to synthesize body proteins
  • May also be converted into fatty acids and stored in fat tissue

BPK 110 (11 decks)

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