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Human Structure & Function > Are you what you eat? > Flashcards

Are you what you eat? Flashcards

1
Q

What is an Enzyme?

A
  • A protein catalyst that increases the rate at which a chemical reaction proceeds, without the enzyme being permanently changed.
  • Highly specific – Active site on an enzyme can only bind to specific reactant.
  • Many different enzymes needed in the body for different chemical reactions.
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2
Q

What does lipase, protease, amylase breakdown?

A
  • Lipase- enzyme that breaks down lipids
  • Protease- breaks down proteins
  • Amylase- breaks down carbohydrates
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3
Q

What is Enzyme Action?

A

The enzyme brings the two reacting molecules together. After the reaction, the unaltered enzyme can be used again.

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4
Q

What is the Digestive Tract called?

A

Digestive tract: also called alimentary tract.

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5
Q

What are Accessory Organs?

A

Accessory organs: Primarily glands, secrete fluids into tract.

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6
Q

What are the organs of the Digestive System?

A
  • Oral cavity (mouth) with salivary glands.
  • Pharynx (throat).
  • Oesophagus
  • Stomach
  • Small Intestines (duodenum, ileum, jejunum) with liver, gall bladder & pancreas as accessory organs.
  • Large Intestine including cecum, colon, rectum & anal canal.
  • Anus
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7
Q

What are the functions of the Digestive System?

A
  1. Ingestion: Introduction of food into stomach (via mouth).
  2. Mastication: Chewing. Chemical digestion requires large surface area so breaking down large particles mechanically facilitates chemical digestion.
  3. Secretion: Lubricate, liquefy, digest (e.g. Mucus: secreted along entire digestive tract, lubricates food, coats and protects lining).
  4. Digestion: Mechanical and chemical digestion of food into nutrients.
  5. Absorption: Movement of nutrients out of digestive tract into cells.
  6. Elimination: Waste products removed from body; faeces. Defecation.
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8
Q

What is the Histology of the Digestive System?

A
  1. Mucosa: innermost layer, secrets mucus.
  2. Submucosa: connective tissue layer, contains blood vessels, nerves etc.
  3. Muscularis: 2/3 muscle layers, movement & secretion.
  4. Serosa / Adventitia: outermost layer, connective tissue, stability.
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9
Q

What is Peritoneum?

A

The walls & organs of the abdominal cavity are lined with serous membranes.

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10
Q

What is the Visceral Peritoneum & Parietal Peritoneum?

A
  • Visceral Peritoneum-Covers organs.

- Parietal Peritoneum-Covers interior surface of body wall.

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11
Q

What is Mesenteries?

A

Mesenteries-Peritoneum (epithelial tissue) which connects organs together. Routes by which vessels & nerves pass from body wall to organs.

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12
Q

What is Greater & Lesser Omentum?

A
  • Greater Omentum-Connects stomach to transverse colon.

- Lesser Omentum-Connects stomach to liver & diaphragm.

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13
Q

What does the Oral Cavity do in Digestion?

A
  • Digestion begins in the oral cavity (mouth).
  • Hard Palate: Hard bone, anterior.
  • Soft palate: Soft muscle, posterior.
  • Tongue
  • Teeth
  • Masticate (chew) food and turn it into a bolus.
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14
Q

What are the sets & types of teeth?

A

-Two sets:
Primary, Milk- Childhood
Permanent or Secondary- Adult (32)
-Types: Incisors, canines, premolars, molars

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15
Q

What do the Salivary Glands do in Digestion?

A
  • Salivary glands (green) – produce & secret saliva into the oral cavity.
  • Saliva – protects oral cavity, moistens, lubricates and digests food.
  • Amylase – enzyme found in saliva that breaks down carbohydrates into smaller sugars.
  • Lysozyme – antibacterial enzyme
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16
Q

What doe the Pharynx connect to and what does Uvula do?

A

-Pharynx (throat) – connects oral cavity to the oesophagus.

oUvula (soft palate) prevents food/drink from entering the nasopharynx.

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17
Q

What is the Oesophagus and what does the Epiglottis do?

A

-Oesophagus – tube that connects pharynx to stomach. 25cm long, lies posteriorly to the trachea.
oEpiglottis prevents food/drink from entering the trachea.

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18
Q

What are the phases of Swallowing?

A
  1. Voluntary phase: Tongue pushes bolus to back of oral cavity towards pharynx (oropharynx).
  2. Pharyngeal phase: Soft palate (Uvula) close off the nasopharynx. Bolus touches receptors on oropharynx and swallowing reflex moves bolus down pharynx and into oesophagus. Epiglottis covers trachea.
  3. Oesophageal phase: bolus is moved down oesophagus towards stomach by peristalsis.
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19
Q

What is Peristalsis and the process?

A
  • Process by which food moves through the gut. Waves of smooth muscle relaxations & contractions.
    1. A wave of smooth muscle relaxation moves ahead of the bolus, allowing the digestive tract to expand.
    2. A wave of contraction of the smooth muscle behind the bolus propels it through the digestive tract.
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20
Q

What does the Stomach do in Digestion?

A
  • Located in abdomen. ‘holding point’ for food.
  • Food comes from the oesophagus and the stomach mixes it (churns) into chyme (thick liquid).
  • Produces mucus, hydrochloric acid, protein digesting enzymes (pepsin).
  • Contains a thick mucus layer that lubricates and protects epithelial cells on stomach wall from acid pH 2-3.
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21
Q

What are the openings in the stomach?

A
  • Gastroesophageal (cardiac): to oesophagus

- Pyloric: to duodenum

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22
Q

What are the parts of the stomach?

A
  • Cardiac
  • Fundus
  • Body
  • Pyloric: antrum and canal
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23
Q

What are the layers of the stomach?

A

-Visceral peritoneum or serosa
-Muscularis: three layers
o Outer longitudinal
o Middle circular
o Inner oblique
-Submucosa
-Mucosa
-Rugae: folds in stomach wall that allow stomach to stretch after eating

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24
Q

What are the movements if the stomach?

A
  • 3 muscular layers enable churning of food. Make Chyme.
  • Combination of mixing waves (80%) and peristaltic waves (20%)
  • Both oesophageal and pyloric sphincters are closed.
  • Stomach empties every 4hrs (6-8 after a fatty meal)
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25
Q

What does the Small Intestine do in Digestion?

A
  • Very long ~6m, small diameter.

- Large surface area for efficient absorption of nutrients.

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26
Q

What are the divisions of the small intestine?

A

oDuodenum- first 25 cm beyond the pyloric sphincter.
oJejunum- 2.5 m.
oIleum- 3.5 m.

27
Q

What do the folds do in the small intestine and what helps this occur?

A
  • ‘Folds’ increase surface area of small intestine 600-fold. Increase absorption.
    1. Plicae circulares: Circular folds in the wall of the small intestine
    2. Villi: Folds of the mucosa that contain capillaries and lacteals.
    3. Microvilli: Small folds on epithelial cell surface.
28
Q

What does the Duodenum do in the Small Intestine?

A
  • Chyme mixes with various digestive enzymes.
  • Liver / gall bladder: Bile enters via the common bile duct, emulsifies fats.
  • Pancreas: enzymes enter via the pancreatic duct.
29
Q

What does the Liver do in Digestion?

A

Makes bile ~100ml/day. Stores glucose (as glycogen) and lipids for energy. Detoxification.

30
Q

What does the Gallbladder do in Digestion?

A

Stores concentrated bile.

31
Q

What does the Pancreas do in Digestion?

A

Produces digestive enzymes. Produces insulin and glucagon for blood sugar homeostasis.

32
Q

What does the Large Intestine do in Digestion?

A
  • Absorption of water.
  • Extends from ileocecal junction to anus.
  • Consists of cecum, colon (ascending, transverse, descending, sigmoid), rectum, anal canal.
  • Bacteria / microbes synthesise vitamin B & K.
    o18-24hr transit time; chyme -> faeces.
    o1500 mL chyme enter the cecum, 90% reabsorbed yielding 80-150 mL of faeces.
    oDefecation reflex
33
Q

Where does Digestion occur in the body?

A

-Digestion – mouth, stomach, small intestine.
Breakdown of food molecules for absorption into circulation.
oMechanical: breaks large food particles too small.
oChemical: breaking of covalent bonds by digestive enzymes.

34
Q

What does Absorption do in the body?

A

-Absorption – nutrients from the small intestine, water from the large intestine.
oMolecules are moved out of digestive tract and into circulation for distribution throughout body.

35
Q

Why are chemicals take into the body?

A
  • Produce energy.

- Provide building blocks to build other molecules.

36
Q

What are the classes of nutrients?

A

carbohydrates, proteins, lipids, vitamins, minerals, water

37
Q

What are the major organic nutrients?

A
  • Carbohydrates, proteins & lipids are major organic nutrients (organic =contains carbon).
  • Need large amounts of carbs, proteins, lipids & water
  • Only need small amounts of vitamins & minerals
  • Taken into body without being digested
38
Q

What are essential nutrients?

A

Essential nutrients – are chemicals that must be taken into the body, because we can’t make them ourselves.
-Include some amino acids/fatty acids/carbs, water, most vitamins & minerals

39
Q

Give examples of the nutrient. classes.

A
  1. Carbohydrates – mono / di / polysaccharides - plants, vegetables
  2. Lipids – triglycerides - oils, dairy, animal fat, eggs
  3. Proteins – chains of amino acids - meat, fish, poultry
  4. Vitamins – organic molecules (vit A,B,E) – animal and plants products
  5. Minerals – inorganic nutrients (calcium, iron) – animal and plant products
  6. Water
40
Q

What are the recommended amounts for carbs, proteins & lipids?

A

-Carbohydrates
o 45-65% of daily intake of kilocalories
-Lipids
o 20-35% or less of total daily kilocalories
-Proteins
o 10-35% of total kilocalories per day
-60% 30% 10% (Carbohydrates>Lipids>Proteins)
-Consider personal needs & source.

41
Q

What are Carbohydrates as a Nutrient in the body?

A

-Most come from plants (exception lactose from milk)
-Contain carbon (C), hydrogen (H) and oxygen (O) = CHO.
-2H and 1O for every C (the 2H: 1O ratio is same as for water).
Carbo = carbon; hydrate = water/hydrated
-Large molecules are made up of small building blocks
oMonosaccharides (mono = 1, saccharide = sugar)

42
Q

Examples of Monosaccharides

A 
o      Glucose (blood sugar) 
o	Fructose (fruit sugar) 
o	Galactose (milk sugar)
43
Q

Examples of Disaccharides

A
  • Sucrose (table sugar) = glucose + fructose
  • Lactose (milk) = glucose + galactose
  • Maltose = glucose + glucose
44
Q

Examples of Polysaccharides

A

-Long chains - 3000+ monosaccharides
-Glycogen
oAnimal polysaccharide
oGlucose molecules
oStored in humans in liver & muscle
-Starch & cellulose
oPlant polysaccharides
oHumans break down starch
-energy
oHuman can’t break down cellulose
-dietary fibre

45
Q

How are Carbohydrates absorbed in the body?

A
  • Polysaccharide chain e.g. glycogen. Digested by saliva in oral cavity & pancreatic amylase in duodenum.
    -Disaccharide chain e.g. sucrose. Digested by sucrase in the intestine.
    Monosaccharide chain e.g. glucose. Glucose absorbed into blood via villi / microvilli in intestine. Transported to liver via hepatic portal vein.
46
Q

How are Carbohydrates used in the body?

A
  • Glucose= produce ATP
  • Excess glucose= glycogen and stored in muscles and liver cells.
  • Excess beyond storage is converted to fat.
  • Sugars also become part of DNA, RNA, and ATP, glycoproteins, glycolipids.
47
Q

What do Proteins contain?

A

Contain carbon (C), hydrogen (H) and oxygen (O), nitrogen (N), sometimes sulphur S(S).

48
Q

What are Amino Acids?

A
  • Amino acids are the basic building blocks
  • Each amino acid has an amine group (NH2), a carboxyl group (COOH), a hydrogen and a side group.
  • Side group is what is different between amino acids.
  • Amino acids link together to form peptides and proteins.
  • Amino acids are not stored in the body.
49
Q

What are Essential & Non-Essential Amino Acids?

A
  • Essential amino acids, can’t be produced by body so must be obtained from the diet, e.g. histidine, isoleucine (9 in total).
  • Non-essential amino acids are still required by our body, but these we can synthesize from essential amino acids.
50
Q

What is the function of Proteins?

A 
-Regulate body functions.
oGlobular proteins – haemoglobin
oStructural - muscle proteins or CT 
oCell membrane transport
oEnzymes
oHormones
oAntibodies
51
Q

What are Complete & Incomplete Proteins + examples?

A

-Complete protein – food that contains enough of all 9 essential amino acids.
oMeat, fish, poultry, milk, cheese eggs
-Incomplete protein
oLeafy green vegetables, grains, legumes –have to mix these to get all the amino acids.

52
Q

How are Proteins Absorbed in the body?

A
  • Protein (long chain of amino acids) digested by pepsin in stomach.
  • Polypeptides digested by trypsin in duodenum.
  • Peptides and individual amino acids are absorbed into the blood via villi / microvilli in intestine.
53
Q

What are Lipids composed of?

A
  • Protein (long chain of amino acids) Digested by pepsin in stomach.
  • Polypeptides digested by trypsin in duodenum.
  • Peptides and individual amino acids are absorbed into the blood via villi / microvilli in intestine.
54
Q

What are Triglycerides?

A

-Glycerol + 3 fatty acids
-Fatty acids
oDifferent lengths (e.g. 14 or 18 C atoms.

55
Q

What are Saturation, Saturated, Unsaturated, Trans Fats?

A

Saturation – how many H atoms on each chain.
Saturated– animal fats, e.g. beef, pork, milk, cheese, butter.
Unsaturated – contains one or more double bonds in the carbon chain, so there is less H atoms, more relaxed structure (liquid at RT).
Trans fats – unsaturated fats that are artificially altered to be more saturated (CVS risk).

56
Q

How are Lipids absorbed?

A
  • Lipid (triglycerides) digestion begins in the duodenum.
  • Bile from the gall bladder emulsifies lipids.
  • Lipase from the pancreas causes further breakdown
  • Short chain fatty acids (monoglycerides) are absorbed into the lymphatic system via lacteals.
  • Lipids are stored in the adipose tissue and liver until needed.
57
Q

How are Lipids used in the body?

A
  • Triglycerides: used to produce ATP (excess stored in adipose or liver).
  • Cholesterol: found in liver & egg yolks or manufactured by body. Component of plasma membranes modified to form bile salts.
  • Phospholipids: major components of plasma membranes, myelin sheath, part of bile.
  • Eicosanoids: derived from fatty acids. Involved in inflammation, blood clotting, tissue repair, smooth muscle contraction.
58
Q

How is Water Absorbed in the body?

A
  • Approximately 9L of water enters the digestive tract each day.
  • 99% of water entering the intestine is absorbed.
  • Water can move across the intestinal wall in either direction if required.
  • Ions: sodium, potassium, calcium, magnesium, phosphate are actively transported.
59
Q

What are Vitamins?

A
  • Organic molecules in very small quantities in food.
  • Essential for normal metabolism and can’t be produced by the body.
  • No one food provides all necessary vitamins
  • Some vitamins produced by intestinal bacterial e.g. vitamin K
  • Vitamins can be fat soluble (A, D, E, K) or water soluble (B and C vitamins)
60
Q

What happens when the body has too much Vitamins?

A
  • Vit C – stomach inflammation; diarrhea.
  • Vit A – toxic during pregnancy
  • Vit D - alter calcium metabolism
61
Q

What are Vitamin Deficiencies?

A
  • Vit D – rickets
  • Vit C–scurvy
  • Vit B1 (thiamine) – beriberi
62
Q

What are Minerals?

A

-Inorganic nutrients
oMajor minerals >100 mg/day
-Calcium, magnesium, sodium, potassium • Trace minerals < 100 mg/day selenium, zinc, copper.
-Components of co-enzymes, some vitamins, haemoglobin, organic molecules.

63
Q

What are the functions of Minerals?

A

oMembrane potential & action potentials
oAdd mechanical strength to bones & teeth
-Available from both plant and animal-based foods.

64
Q

What are Mineral Deficiencies?

A
  • Iron – anaemia
  • Potassium – muscle weakness, abnormal heart function
  • Iodine - goitre

Human Structure & Function (11 decks)

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