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π”Ήπ•šπ• π•π• π•˜π•ͺ F4 > Chapter 9: Nutrition and the Human Digestive System > Flashcards

Chapter 9: Nutrition and the Human Digestive System Flashcards

1
Q

The human digestive system comprises of the ________ _____ which starts at the mouth and ends at the anus.

A
  • alimentary canal
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2
Q

What are the six main processes of human nutrition?

A
  • Ingestion
  • Peristalsis
  • Digestion
  • Absorption
  • Assimilation
  • Excretion/ Egestion
    ( I Pulled Down Alan’s Ass Eagerly )
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3
Q

What occurs in all the six main nutrition processes?

A

Ingestion
- food is broken down into soluble molecules
Peristalsis
- food is moved along the alimentary canal by muscular contractions
Digestion
- broken down into soluble molecules
Absorption
- absorbed food molecules taken up by cells for metabolism
Egestion
- undigested and unabsorbed materials removed

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4
Q

What are the 2 types of digestion?

A
  • Physical digestion

- Chemical digestion

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5
Q

Give some general info about physical and chemical digestion.

A 
Physical
- chewing in the mouth cavity
- peristalsis along the alimentary canal
Chemical
- reactions are catalyzed by digestive enzymes
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6
Q

Explain physical digestion in detail.

A
  • chewing in the mouth cavity increases the surface area of food particles for enzyme reaction
  • allows a bolus to be formed
  • peristalsis is produced by alternate contraction and relaxation of the muscles
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7
Q

Explain the chemical digestion in the mouth in detail.

A
  • salivary amylase hydrolyses starch to form maltose
    Starch + water β€”-salivary amylaseβ€”> Maltose
  • mouth which has a neutral pH becomes acidic overnight which is where we should use toothpaste
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8
Q

Explain the digestion of protein in the stomach. ( gastric juices and secretion )

A
  • stomach has gastric glands to produce gastric juices
  • differentiated cells in the epithelial lining of the stomach wall form different gastric glands
  • chief cells secrete pepsinogen which provides an acidic medium for pepsin to function
  • parietal cells secrete HCl
  • goblet cells secrete mucus
  • optimum pH is 2
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9
Q

Explain the digestion of protein in the stomach. ( action of enzymes and function of mucus )

A
  • mucus protects the walls of the stomach from being corroded by acid
  • pepsin hydrolysis protein into polypeptides
  • rennin converts caseinogen ( soluble ) in milk to casein ( insoluble )
  • churned food remains in the stomach for 4h to become chyme
  • the chyme is slowly released into the duodenum
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10
Q

What is the function of HCl?

A
  • activate pepsinogen into pepsin
  • provides an acidic medium for chemical reactions to occur
  • kills bacteria
  • stops the action of salivary amylase
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11
Q

The small intestine consists of 2 main parts: ______ and ______. The optimum pH for digestion in the small intestine is ____ ___.

A
  • duodenum
  • ileum
  • pH 8.5
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12
Q

Chyme from the stomach enters into the ______ and the digestion of _____ starts. Duodenum does not produce any digestive juices but it receives 2 secretions:

  • _____ from the liver
  • _____ _____ secreted by pancreas
A
  • duodenum
  • lipid
  • bile
  • pancreatic juices
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13
Q

What are the functions of the liver and bile?

A

Liver
- produces bile ( stored in the gall bladder and released through the bile duct )
Bile
- emulsifies fats
- breaks up large globules into droplets to increase surface area for lipase to act
- prepares an alkaline medium
- neutralizes acid in the chyme

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14
Q

What are the functions of the pancreas and pancreatic juices?

A

Pancreas
- secretes pancreatic juices: lipase, pancreatic amylase, and trypsin
Pancreatic juices
- lipase hydrolyses fats into fatty acid and glycerol
- pancreatic amylase hydrolyses starch into maltose
- trypsin hydrolyses polypeptide into peptides

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15
Q

The digestion of food is completed in the _____ to produce the _____ _______. The wall of the ileum has intestinal glands which secrete ____ ____ that contains enzymes such as ____, _____, _____, _____ and _____.

A
  • ileum
  • final products
  • intestinal juices
  • maltase
  • sucrase
  • lactase
  • erepsin
  • lipase
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16
Q

State the digestion of carbohydrates, proteins, and lipids in the ileum.

A

Carbohydrates
- maltase hydrolyses maltose into glucose
- sucrase hydrolyses sucrose into fructose and glucose
- lactase hydrolyses lactose into galactose and glucose
Proteins
- erepsin hydrolyses peptides into amino acids
Lipids
- lipase hydrolyses fats into glycerol and fatty acids

17
Q

The final products of digestion, minerals, vitamins as well as most water are _______ by finger-like projections in the wall of the ileum called ____. The ileum is ____ and ____ to provide a large surface area for absorption of digested food. It has numerous ___ to absorb nutrients.

A
  • absorbed
  • villi
  • long
  • folded
  • villi
18
Q

Explain the structure and the adaptations of villus for the absorption of digested products.

A

Structure
- tiny projections
- each villus consists of lacteal, blood capillary, and thin epithelium
- epithelium has many tiny projections called microvilli to provide a large surface area
Adaptations
- very thin epithelium = allow rapid diffusion
- a network of blood capillaries = allow rapid absorption
- many lacteals = absorb lipid-soluble vitamins, fatty acid, and glycerol
- many microvilli

19
Q

Explain the absorption of nutrients in the villus.

A

Into lacteal:
- fatty acids and glycerols in the form of fat droplets by simple diffusion
- Vitamin A, D, E, and K by simple diffusion
Into blood capillaries:
- Fructose by facilitated diffusion
- Glucose, galactose, amino acids, and minerals by active transport
- Vitamins B and C are absorbed with water which undergoes osmosis

20
Q

What is assimilation?

A
  • movement of digested food molecules into the cells of the body where they are used
21
Q

Both the _______ system and ______ system are involved in transporting nutrients that are absorbed into the villi out of the ileum.

A
  • circulatory

- lymphatic

22
Q

Nutrients are absorbed into the blood capillaries of the villus. These nutrients are transported out of the ileum by _____ _____ ____ to the ____. These nutrients are then distributed to other body cells through the ______ system for assimilation.

A
  • hepatic portal vein
  • liver
  • circulatory
23
Q

Nutrients are absorbed into the lacteal of the villus. These nutrients are transported out of the ileum by a ______ vessel called _____ duct for _____ in the lymphatic system before they are finally returned to the circulatory system via the left _______ ___.

A
  • lymphatic
  • thoracic
  • circulation
  • subclavian vein
24
Q

Explain the assimilation of glucose.

A
  • glucose is used in cellular respiration
  • excess glucose is converted into glycogen and is stored in the liver and muscle cells
  • if blood glucose level is low, glycogen is converted to glucose
  • glucose can also be converted to fat when there is excess glycogen
25
Q

Explain the assimilation of amino acids and lipids.

A

Amino acids
- used to synthesis proteins such as fibrinogen and prothrombin
- Excess cannot be stored so converted into urea through deamination
- transported to the kidney to be excreted through the urine
Lipids
-synthesis about 80% of cholesterol
- can be broken down into glucose if required

26
Q

What is defaecation?

A
  • process where feces is removed from the body which is controlled by the muscles around the rectum of the large intestine and anus
27
Q

What is the function of the large intestine?

A
  • reabsorption of water in the colon
  • synthesis of vitamin K and B12 by bacteria in the caecum
  • faeces formation
28
Q

Explain the formation of faeces.

A
  • undigested food passes through the caecum, colon and rectum by peristalsis
  • movement of undigested food is smoothened by mucus
  • water is reabsorbed in the colon
  • semi-solid material which is called faeces is formed in the rectum
  • brown colour of the faeces is due to the bile pigments
  • temporarily stored in the rectum before being forced out by muscle contraction which is known as defaecation
29
Q

What is a balanced diet?

A
  • contains all seven classes of food in the correct proportion according to the needs of the body
30
Q

Explain the energy value in food.

A
  • quantity of heat produced when 1g of food is completely oxidised
  • unit is Jg-1
  • 1 calorie = 4.2J
  • Formula given is :
    Energy value ( kJg-1 ) = Mass of water (g) . Temperature increase/ mass of food sample (g)
31
Q

Weight loss surgery is one of a variety of procedures opted by obese people to reduce weight. Digestive organs are modified by reducing the size of the stomach by joining the ____ to the ______ which is known as _____ _____ to block absorption of food.

A
  • ileum
  • stomach
  • gastric bypass
32
Q

What are the effects of gastric bypass?

A
  • nutritional deficiency
  • must voluntarily take minerals and vitamins
  • can cause anaemia and osteoporosis
33
Q

What are the health issues related to defaecation?

A
  • constipation
  • colon cancer
  • haemorrhoids ( piles )
34
Q

Explain the health issues related to defaecation.

A

Constipation
- dry hard faeces which occurs when food moves slowly along large intestine
- abnormally large water is reabsorbed
- causes discomfort
Colon cancer
- caused by prolonged constipation which leads to the accumulation of faeces at the rectum
- toxic substances induce the cells and divide out of control
Haemorrhoids
- due to problems in defaecation
- faeces becomes hard and applies pressure towards the blood vessels in the anus
- blood vessels become swollen or inflamed

35
Q

What are the health issues related to eating habits?

A
  • gastritis
  • muscle dysmorphia
  • anorexia nervosa
  • bulimia nervosa
36
Q

Explain the health issues related to eating habits?

A

Gastritis
- eating late and irregularly
- empty stomach stimulated HCL secretion which acts on the wall and causes inflammation
- sharp pain in the stomach and vomiting
Muscle dysmorphia
- an obsessive mental disorder that carries a delusional belief that their own body is too skinny
- indulge in dietary restrictions and drugs
Anorexia nervosa
- a psychological disorder related to ED
- among young women who feel too fat
- refrains from eating bur exercises excessively
Bulimia nervosa
- a psychological eating disorder
- eat excessively and they induce vomiting or use laxatives
- suffers weight loss and malnutrition

π”Ήπ•šπ• π•π• π•˜π•ͺ F4 (10 decks)

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