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Human Biology > Digestive System > Flashcards

Digestive System Flashcards

1
Q

Ingestion

A

The act of eating

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2
Q

Digestion

A

The breaking down of food into molecules small enough for the body to absorb

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3
Q

Absorption

A

The take-up of the products of digestion

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4
Q

Elimination

A

The removal of undigested materials out of the digestive tract

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5
Q

Alimentary canal

A

Consists of:

  • A mouth
  • An anus
  • Specialized regions associated with one-way food flow
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6
Q

Food flow

A

Food moves:

  • Into the pharynx/throat
  • down the esophagus
  • Into the stomach, where food is ground and stored
  • Into the intestines, where chemical digestion and nutrient absorption occur
  • Undigested food comes out the anus
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7
Q

Human digestion

A

In humans, food is:

  • Ingested and chewed in the oral cavity (mouth)
  • Pushed by the tongue into the pharynx
  • Moved by contraction and relaxation (peristalsis) by smooth muscle
  • Moved out of the stomach by sphincters
  • The final steps of digestion and absorption occur in the small intestine
  • Undigested food is moved through the large intestine, stored in the rectum, and expelled out the anus
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8
Q

Oral cavity

A

Mechanical and chemical digestion begins in the mouth

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9
Q

Chewing

A

Chewing cuts, smashes and grinds food, making it easier to swallow

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10
Q

Tongue

A

The tongue tastes and shapes food into a ball called a bolus and moves it towards the pharynx

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11
Q

Salivary glands

A

Release a slippery glycoprotein:

  • Moistens and lubricates food for easier swallowing
  • Buffers that neutralize acids
  • Salivary amylase that begins the hydrolysis of starch
  • Antibacterial agents that kill some bacteria injested with food
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12
Q

Air moves

A

Air moves from the pharynx, into the larynx, past the vocal cords and into the lungs

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13
Q

Swallowed food

A
  • Moves from the pharynx into the esophagus and stomach

- During swallowing, the tip of the larynx moves upward, preventing food from entering the trachea

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14
Q

The stomach

A

Can stretch and hold up to 2 liters of food and drink

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15
Q

Chemical digestion

A
  • Occurs in the stomach
  • The stomach secretes gastric juice made up of mucus, a protein-digesting enzyme and a strong acid with a ph of about 2 that kills bacteria, breaks apart food cells, and denatures proteins
  • Pepsinogen and HCl produce active pepsin
  • Pepsinogen, H+, and Cl are secreted into the stomach
  • HCl conversts some pesinogen to pepsin
  • Pepsin helps active more pepsinogen, starting a chain reaction
  • Pepsin begins the chemical digestion of proteins
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16
Q

Protecting the stomach wall from gastric juices

A
  • The secretion of pepsin in the inactive form of pepsinogen helps protect the cells of gastric glands
  • Mucus helps protect the lining against HCl and pepsin
  • New cells begin lining the stomach every 3 days, replacing damaged cells
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17
Q

Acid reflux

A

-When chyme in the stomach backs into the esophagus causing heartburn, which can lead to GERD

18
Q

Ulcers

A

-Form in the stomach and duodenum from bacterial infections

19
Q

Small intestine

A
  • Is named for its small diameter
  • About 6 meters long
  • The site of much chemical digestion
  • Where the most nutrients are absorbed
20
Q

Duodenum

A

-The first 25 cm of the small intestine, where chyme squirted from the stomach is mixed with digestive juices from the pancreas, liver, gallbladder, and gland cells in the intestinal walls

21
Q

Pancreas

A

-Produces pancreatic juice containing a mixture of digestive enzymes and an alkaline solution rich in bicarbonate

22
Q

Liver

A
  • The epithelial cells of the liver (called hepatocytes) produce bile, which is delivered to the gallbladder where it is stored until it is needed
  • Bile is delivered to the gallbladder where it is stored
  • Bile breaks fat into small droplets (emulsification) that are easier to attack
23
Q

Surface area of small intestine

A

The surface area of the small intestine is greatly increased by:

  • Folds in the lining
  • Fingerlike projections called villi
  • Tiny projections on the surface of the intestinal cells called microvilli
24
Q

Epithelial cells

A

-Nutrients pass into epithelial cells by diffusion and against concentration gradients

25
Q

Fatty Acids

A
  • Fatty acids and glycerol are recombined into fats
  • Coated with proteins
  • Transported into lymph vessels (lymphatic capillaries called lacteals)
26
Q

Amino acids

A

-Pass out of the intestinal epithelium, across the thin walls of the capillaries, into the blood, and finally into the liver

27
Q

Hepatic portal vein

A

-Blood from the digestive tract drains into the hepatic portal vein into the liver

28
Q

The liver

A

The liver performs many functions:

  • Converts glucose into glycogen
  • Stores glucose and releases sugars into the blood
  • Synthesizes many proteins including blood clotting and lipoproteins that transport fats and cholesterol to body cells
  • Mediates substances absorbed into the digestive tract into less toxic forms and makes bile
29
Q

Large intestine

A
  • Also known as the colon
  • Is about 1.5 m long and 5 cm in diameter
  • Has a pouch called the cecum near its junction with the small intestine which bears the appendix
  • Contains large populations of E. coli, which produce important vitamins
  • Absorbs vitamins and water into the bloodstream
  • Helps form feces which are stored in the rectum until elimination
30
Q

Basic Nutritional Needs

A
  • Must obtain fuel to power body activities
  • Organic molecules to build body molecules
  • Essential nutrients or substance that an animal can’t make itself
31
Q

Cellular respiration

A
  • Produces the body’s energy currency, ATP, by oxidizing organic molecules digested from food and usually using carbohydrates or fats as fuel
  • A gram of fat has more than twice the calories than as carbs or proteins
32
Q

4 Classes of Essential Nutrients

A
  • Essential fatty acids
  • Essential amino acids
  • Vitamins
  • Minerals
33
Q

Essential fatty acids

A
  • Are used for making phospholipids of cell membranes

- Found in seeds, grains, and veggies

34
Q

Essential amino acids

A
  • Used to make proteins

- Found in eggs, meat, and milk

35
Q

Vitamins

A
  • Organic nutrients
  • May be water soluble (B or C)
  • May be fat soluble (A, D, E, or K)
36
Q

Vitamin A

A

-Needed for teeth and bones

37
Q

Vitamin B

A

-Needed for CNS and proper RBC function

38
Q

Vitamin C

A

-Helps immune system and absorbs iron

39
Q

Vitamin D

A

-Needed for proper absorption of Calcium in the gut

40
Q

Vitamin E

A

Antioxidant

41
Q

Vitamin K

A

-Needed for proper blood clotting

42
Q

Minerals

A
  • Simple inorganic nutrients
  • Calcium and phosphorus are required in larger amounts
  • Iron is needed to make hemoglobin
  • Iodine makes thyroid hormones

Human Biology (16 decks)

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