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BMS192 > W6 Digestive Tract > Flashcards

W6 Digestive Tract Flashcards

1
Q

Discuss the generalized function of the digestive system

A

The organs of the digestive system together prepare nutrients for absorption and for use by millions of body cells

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2
Q

List, in sequence, each of the components or segments of the alimentary canal from mouth to anus, and identify the accessory organs of digestion located within the gastrointestinal tract or that open into it.

A

Main organs of the DS form the gastrointestinal tract (GI) tract, extends through the abdominopelvic cavity

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3
Q

List and describe the four layers of the wall of the gastrointestinal tract.

A

Has 4 layers.

From luminal side:

  1. Mucosa
  2. Submucosa
  3. Muscularis
  4. Serosa
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4
Q

Discuss the major modifications of the layers of the digestive tract.

A

Simple columnar epithelim through most of the tract.

Stratified squamous eputhelum in mouth, esophagus and rectum.

Exocrine glands empty secretions into the lumen

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5
Q

List and describe the structures of the mouth.

A

Hard and soft palate:

Hard palate consists of portions of four bones: 2 maxillae and two palatines.

Soft palate form the partition between the mouth and nasopharyn is made of muscle arranged in an arch

Tongue: 3 parts, root, tip, body.

Papillae

Lingual frenulum anchors tongue to the floor of mouth,

Tongues intrinsic muscles are important for speach.

Extrinsic muscle are important for swallowing and speech. Taste buds Salivary glands

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6
Q

Identify and compare the structures and secretions of the salivary glands.

A

Salivary glands: secrete 1 litre of saliva each day

  • Parotid glands - produce watery saliva containing enzymes (serous)
  • Submandibular glands are compoud glands that contain enzymes and mucus
  • Sublingual glands produce mucous saliva Serous cells Mucos cells
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7
Q

Discuss the structural components of a typical tooth, and identify by name and number the deciduous and permanent teeth.

A

Cross section of tooth:

  • Enamel
  • Cementum
  • Surrounding dentin layer
  • Pulp
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8
Q

Identify the structural divisions of the pharynx.

A

Tube which food bolus passes when moved from the mouth to the esophagus by the process of deglutition.

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9
Q

Describe the location and structure of the oesophagus.

A

Tube that extends from the pharynx to the stomach.

Lined with stratified epithelium

  • Cervical part
  • Thoracic part
  • Abdominal part

Each end is encircled by muscular sphincters

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10
Q

Discuss the size, position and structure of the stomach.

A

Located in the upper part of the abdominal cavity, under the liver and diaphragm.

Size varies according to factors such as gender. When no food it is the size of a large sausage. In adults its capacity ranges from 1-1.15 litres

Divided into:

Cardiac region

  • Fundus
  • Body
  • Pylorus Curves of stomach

Sphincter muscles:

  • Lesser & Greater curve Sphincter muscles: Lwr esophageal sphincter (cardiac sphincter) controls the opening of the esophagus into the stomach.
  • Pyloric sphincter controls the outlet of the pyloric portion of the stomach into the duodenum
  • Gastric Muscularis

Stomach Wall - gastic mucosa

  • Gastric mucosa: has epithetlial lining rugae marked by gastric pits.
  • Gastric glands: secrete gastric juice
  • Chief cells: secrete enzymes
  • Parietal cells: secrete hydrochloric acid, vit b12 Endocrine cells: secrete gastrin & ghrelin
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11
Q

Describe the functions of the stomach.

A

Secretes gastric juice to aid in digestion of food.

Breaks food into small particles and mixes with gastric juice

Secretes intrinsic factor

Performs limited absorption

Produces gastric and ghrelin (hunger hormone)

Helps protect the body from pathogenic bacteria swallowed with fuel

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12
Q

Discuss the size, position, divisions, and wall of the small and large intestines.

A

Small intestine Tube approx 2.5cm wide and 6m long.

Divisions:

Duodenum: upper most division approx 25cm long, shaped like the letter C

Jejunum: approx 2.5m long Ileum: approx 3.5m long.

Digestion and secretion of enzymes take place in the Jejunum while absorption of vit B and coupled bile salts take place in the ileum.

Wall of the small intestine: Intestinal lining as plicae (circular folds)

Large Intestine: Size: diameter 6 cm Lengeth approx 1.5-1.8 Divisions

  • Cecum
  • Colon
  • Rectum
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13
Q

Locate and discuss the significance of the vermiform appendix.

A

Vermiform Appendix: accessory organ, reservoir for beneficial gut bacteria

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14
Q

Discuss the peritoneum and its reflections.

A

Large, continuous sheet of seous membrane, many organs covered with visceral peritoneum; parietal peritoneum lines the walll of the abdominopelvic cavity.

Mesentery: projection of the parietal peritoneum

Transverse mesocolon: extension of the peritoneum that supports the transverse colon.

  • Onmentum
  • Abdominal
  • Viscera
  • Transverse colon
  • Greater Omentum
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15
Q

Describe the structures and functions of the liver and gallbladder.

A

Liver

Largest gland in the body weights 1.5kg. Lies under diaphragm Divided into L and R lobe

Hepatic lobules: anatomical units of liver.

Hepatic lobules → portal triad → blood flows to a central vein → sinusoids (low pressure vascular channels) → receives from hepatic artery/ portal vein at the periphery of lobules and deliver it into central veins.

Functions: Involved in metabolizing proteins, fats, carbs (anabolic & catabolic functions).

Production of plasama proteins including albumin, clotting factors and complement.

Detoxification: toxic substances that are either ingest or formed in the intestines → nontoxic substances.

Bile secretion: liver cell secrete 600ml of bile

Contains macrophages that remove bacteria.

Gallbladder: stores bile

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16
Q

Discuss the structure and functions of the pancreas.

A

Grayish pink gland. 12-15cm long weighs approx 60 grams. Structure exocrine portion: produces enzymes and other digestive juices Endocrine portion: secrete glucagon and insulin

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17
Q

Describe the primary functions and mechanisms of the digestive system.

A

To bring essential nutrients into the internal environment so that they are available to each cell of the body.

This is achieved through 6 processes:

  1. Ingestion
  2. Propulsion
  3. Mechinval digestion
  4. Chemical digestion
  5. Absorption
  6. Elimination
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18
Q

Define motility of the digestive tract

A

All movement of the digestive tract. Includes

  1. Propulsion
  2. Mechanical digestion. Work together.

Digestion begins in the mouth when the particle size of ingested food material is reduced by mastication.

→ Churns contents of the GI lumen to mix with digest juices mix → Propels food along the GI tract, eliminating digestive waste from the body

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19
Q

List and explain the three main steps or stages of deglutition.

A
  1. Oral stage: mouth to oropharynx
  2. Pharyngeal state (oropharynx to esophagus): triggered by food against the soft palate, gravity, moving bolus into esophagus.
  3. Esophageal state (esophagus to stomach) involuntary.
20
Q

Differentiate between peristalsis and segmentation.

A

The two main types of motility produced by the smooth muscle of the GI tract.

Peristalsis: The main purpose of propulsion in the GI tract with wave like ripples.

Segmentation: mixing movments, backwards and forwards movement. This can occur together or alternating.

21
Q

Explain how motility in the digestive system is regulated.

A

Controlled by reflexes.

Short reflexes within enteric NS.

Long reflexes involving the brain and PNS via vagus nerve.

Triggers are stretching of an organ due to gut contents or the presences of particular food chemicals such as proteins or lipids.

Propulsion & retropulsion.

Intestinal Motility: acts to mix chyme with digestive fluids from pancreas, liver and intestinal mucosa. peristalsis ↑ as chyme approaches end of the jejunum moving from small → large intestine, takes approx 5 hours

22
Q

Define chemical digestion.

A

The changes in the chemical composition of food as it travels through the digestive tract. (hydrolysis)

23
Q

Discuss the properties of digestive enzymes.

A

Digestive enzymes (extracellular organic protein catalysts). This occurs in the lumen of digestive tract. Enzymes must be continually synthesized.

Break down = ayse

24
Q

Compare and contrast protein, fat, and carbohydrate digestion.

A

Carbs are saccaride compounds.

Polysaccarides are hydrolyzed by amylases to form disaccharides.

Amalyse in saliva

  • Sucrase: digests sucrose to glucose & fructose
  • Lactase: digests lactose to glucose & galactose
  • Maltase: digests maltose to glucose & glucose
  • Proteins are twisted chained of amino acids.

Proteases catalyze hydrolysis of proteins → amino acids.

Pepsin in gastric juice, tryosin in pancreatic juice, peptidases in intestinal brush border.

Fats: must be emulsified by bile in small intestine - lecithin & bile salts emulsify dietary oils and fats in the lumen of the small intestine. Pancreatic lipase fat digesting enzyme.

25
Q

Discuss salivary, gastric, pancreatic, biliary, and intestinal exocrine secretions and how they are controlled

A

Saliva secreted by salivary glands, mucus lubricates food.

Amylase begins digestion of starches. Stimulated by smell and sight of food chemical mechanisim in mouth.

Gastric juices: secreted by gastric glands.

Pepsin: a protease secreted by chief cells that begins the digestion of proteins. → hydrochloric acid: secreted by parietal cells.

Control of gastric secretion

  1. Cephalic phase: mental factors activate the mechanisim, vagus nerve stimulates gastrin production.
  2. Gastric phase: when products of protein digestion reach the pyloric portion of the stomach → stimulates gastrin.
  3. Intestinal phase: Various mechanisims seem to adjust gastric secretion as chyme passes to and through the intestinal tract.

Pancreatic Juice: Enzymes secreted by acinar cells of the pancreas

  • Proteases; trypsin & chymotrypsin
  • Lipases: digest emulsified fats
  • Mucleases; digests nucleic acids DNA RNA
  • Amylase: digest starch
  • Bile: secreted continuously by the liver → stored in gallbladder.
  • Lecithin and bile salts emulsify fats.
  • Intestinal Juice: mucous (goblet cells).
26
Q

Identify and discuss the absorption of nutrients resulting from the digestive process and the structures into which they are absorbed.

A

Absorption: passage of digested molecules through the epithelial cells of the intestinal mucosa into the blood and lymph.

27
Q

Describe the processes of elimination and defecation.

A

Expulsion of feces from the digestive tract.

  1. Food arrives at rectum; external anal spinchter relaxes. internal anal sphincter; contracted
  2. External anal sphincter contracts and internal anal sphincter relaxes.
  3. The external anal spincter relaxes and the internal analy spincter relaxes
28
Q

Define the terms nutrition, macro- & micro- nutrient, essential & non-essential nutrient

A

Macro nutrient: macromolecules such as carbs, lipids and proteins,

Macrominerals: minerals needed in large amounts

Micronutrient: microminerals needed in small amounts.

Essential nutrient: That must be obtained from out diet because our bodies cannot synthesize them.

Non-essential nutrient: our bodies synthesize given the proper raw materials

29
Q

Define metabolism & outline the processes of anabolism and catabolism.

A

Metabolisim the combination of chemical reactions occuring in the body.

Catabolisim: break down molecules

Anabolisim: synthesis of bigger molecules from smaller ones

30
Q

Discuss the role of ATP and the ATP/ADP system in metabolism.

A

ADP → energy from nutrient catabolism → ATP → energy to cellular processes.

31
Q

State the various dietary sources of carbohydrates, lipids and proteins

A

Carbs:

  • Polysaccarides
  • Starches
  • Cellulose.

Disaccharides: found in refined sugar and dairy

Monosaccarides: found in fruit, glucose.

Lipids:

  • Triglycerides: glycerol → 3 fatty acids
  • Phospholipid
  • Cholesterol: only found in animal foods
32
Q

Discuss carbohydrate metabolism and the generation of ATP, including the role of glycolysis, the citric acid cycle and electron transport chain

A

Glucose metabolisim

  1. Glycolisis is a series of chemical reactions, occuring in the cytoplasm cell.
  • Provides cells with energy under conditions of inadequate oxygenation.
  • Breaks down chemical bonds in glucose molecules and releases 5% of the erngy stored in them.

2.Citric acid cycle: Pyruvic acid from glycolysis enters the citrix acid cycle → 2 pyruvic acid molecules have been broke down into 6 carbdon dixoide and 6 h2o. → Electron transport chain to produce lots of ATP 3.

Electron Transport Chain: Hydrogen pump reserved in the mitochondria = ATP

33
Q

Explain what is meant by the terms anaerobic respiration and aerobic respiration.

A

Aerobic respiration: The presence of oxygen glucose is fully metabolized to water and carbon dioxide.

Anaerobic respiration: in the absence of oxygen glucose molecules go through glycolysis.

34
Q

Differentiate between glycogenesis, glycogenolysis, and gluconeogenesis

A

Glycogenesis↑ (form): production of glycogen.

Glycogenolysis↓: break down of glycogen into glucose.

GlucoNE(W)ogenesis ↑↑↑: the creation of new glucose from glycerol if glycogen stores run out

35
Q

Discuss glucose homeostasis

A

Negative feedback loop.

Blood glucose levels are controlled by hormones. Insulin and glucagon.

Insulin is secreted by beta cells of the pancreas to ↓ the blood glucose level.

Glucagon: secreted by alpha cells of the pancreas to ↑ blood glucose levels.

36
Q

Identify the major lipid constituents of the blood and discuss their mechanisms of transport.

A

Lips are hydrophobic do not dissolve in aquenous blood plasma.

Lipoproteins allow lipids to be transported in the blood.

  1. Digest lipids
  2. Digestion continues in stomach
  3. Biles salts break it up into monoglyserides and glyceroles.
  4. Packaged into chylomicrons
  5. Chylomicros proceed along lymp vessels into thorasic duct.
  6. chylomicrons enter the blood stream
  7. enzymes breakdown chylomicrons releases fatty acids and monoglycerides, diffuse into interstituale fluid. 8. Skelatal muscle absorb fatty acid ATP.
  8. LDLS are released into blood stream
  9. Absorbed in peripheral tissues.
  10. Cholesterol that is not used diffuses out of cell and reenters blood stream, → absorbed by high density lipoproteins by liver.
37
Q

Discuss the metabolism of lipids.

A

Lipid catabolisim

Lipid anabolisim

38
Q

Compare and contrast protein anabolism and catabolism

A

Protein anabolisim: process by which proteins are synthesized by ribosomes of the cells,

Protein catabolisim: deamination which takes place in the liver cells forms amonia.

39
Q

Discuss the importance of vitamins and minerals.

A

Necessary for normal metabolisim. most vitamin molecules attach to enzymes or coenzymes.

Inorganic elements : attach to enzymes, to help them function in chemical reactions

40
Q

Define the terms metabolic rate and basal metabolic rate and state how metabolic rates are expressed.

A

Metabolic rate is the energy that must be expended to accomplish work.

Measured in kilocalories per hour or per day

41
Q

Discuss the major factors that influence the basal metabolic rate (BMR) and total metabolic rate.

A

The basal metabolic rate (BMR) varies due to

  • Size
  • body comp
  • gender
  • age
  • thyroid hormone
  • level body temp
  • drugs
  • other factors.
42
Q

Discuss the relationship between body weight and energy intake, output, and balance.

A

Body weight ↑ Energy > energy output

Body weight ↓ energy input < energy output

43
Q

Discuss the mechanisms for regulating food intake.

A

Controlled by the hypothalamus.

Feeding centre - orexigenic effect triggers appetite.

Satiety centre: anorexigenic effect supresses appetite.

Gherlin: induces hunger

Leptin: increases fullness (satiety)

44
Q

Discuss the function of mastication

A

Mechanical digestion begins in the mouth when the particle size of ingested food material is reduced by chewing movements, mastication mixes saliva with food in preparation for swallowing.

45
Q

Discus the dietry sources of proteins

A

Proteins are assembled from amino acids. Must be obtained from diet

BMS192 (10 decks)

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