Digestive System Overview
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Questions and Answers

What are the two main types of digestion that occur in the digestive system?

Mechanical (physical) digestion and chemical (enzymatic) digestion.

What role do enzymes play in the digestive system?

Enzymes act as biological catalysts that speed up the chemical reactions involved in digestion.

How do carbohydrates, proteins, and lipids differ in terms of their digestion and absorption?

Carbohydrates are broken down into sugars, proteins into amino acids, and lipids into fatty acids and glycerol during digestion.

Explain the process of peristalsis and its importance in digestion.

<p>Peristalsis is a series of wave-like muscle contractions that move food through the digestive tract.</p> Signup and view all the answers

What is meant by the term 'absorb' in the context of the digestive system?

<p>To absorb means to deliver nutrients from digested food into the bloodstream.</p> Signup and view all the answers

What type of carbohydrate is cellulose, and what is its primary role in the human diet?

<p>Cellulose is an indigestible carbohydrate that provides fiber in our diet.</p> Signup and view all the answers

What are proteins made of, and what connects the amino acids in their structure?

<p>Proteins are made up of elements C, H, N, O, and S, and amino acids are connected by peptide bonds.</p> Signup and view all the answers

Define the two categories of amino acids and provide an example of each.

<p>Essential amino acids must be supplied in the diet, while non-essential amino acids can be made by the body.</p> Signup and view all the answers

List two functions of proteins in the body.

<p>Proteins serve as enzymes and are involved in muscle contraction.</p> Signup and view all the answers

What are the three types of carbohydrates based on the number of subunits?

<p>Monosaccharides, disaccharides, and polysaccharides.</p> Signup and view all the answers

What role do enzymes play in biological processes?

<p>Enzymes are biological protein catalysts that speed up reactions by recognizing specific molecules.</p> Signup and view all the answers

Name two examples of monosaccharides and where they can be found.

<p>Glucose (source of ATP) and fructose (found in fruits and soft drinks).</p> Signup and view all the answers

Describe the structure of triglycerides.

<p>Triglycerides are composed of glycerol and three fatty acids.</p> Signup and view all the answers

Differentiate between saturated and unsaturated fatty acids.

<p>Saturated fatty acids contain no double bonds, while unsaturated fatty acids have one or more double bonds.</p> Signup and view all the answers

How are disaccharides formed and what must happen before they are absorbed into the blood?

<p>Disaccharides are formed from two monosaccharide subunits and must be digested into monosaccharides before absorption.</p> Signup and view all the answers

What is the composition of sucrose and what common product is it found in?

<p>Sucrose is composed of glucose and fructose, commonly found in table sugar.</p> Signup and view all the answers

What are phospholipids made of, and what is their significance in biological membranes?

<p>Phospholipids are made of glycerol, two fatty acids, and a phosphate group, playing a critical role in forming cell membranes.</p> Signup and view all the answers

Define polysaccharides and provide an example of two types.

<p>Polysaccharides are long chains of monosaccharides and examples include starch and glycogen.</p> Signup and view all the answers

What is the primary role of starch in our diet, and how is it digested?

<p>Starch serves as a main energy source in our diet and is digested into glucose.</p> Signup and view all the answers

Why is glycogen not considered an important source of carbohydrates in our diet?

<p>Glycogen is primarily stored in animal tissues and is not a significant dietary source for humans.</p> Signup and view all the answers

What is the main function of glucose in the human body?

<p>Glucose serves as a primary source of ATP, providing energy for cellular processes.</p> Signup and view all the answers

What are maltose and its significance in digestion?

<p>Maltose is a disaccharide composed of two glucose units and plays a crucial role in carbohydrate digestion by serving as a substrate for enzymes like maltase.</p> Signup and view all the answers

How does the structure of the small intestine facilitate nutrient absorption?

<p>The small intestine has a highly folded surface with villi and microvilli that significantly increase its surface area, enhancing nutrient absorption.</p> Signup and view all the answers

Describe the function of peristalsis in the digestive tract.

<p>Peristalsis is a series of wave-like muscle contractions that moves food along the digestive tract, ensuring efficient digestion and absorption.</p> Signup and view all the answers

What is the role of fatty acids in human physiology?

<p>Fatty acids serve as crucial energy sources and are essential for cell membrane structure and function.</p> Signup and view all the answers

What are the main functions of the organs of digestion featured in animations?

<p>The organs of digestion work together to break down food, absorb nutrients, and eliminate waste products.</p> Signup and view all the answers

What enzyme is responsible for digesting proteins in the stomach?

<p>Pepsin is responsible for digesting proteins in the stomach.</p> Signup and view all the answers

How does excessive secretion of gastric juice lead to gastric ulcers?

<p>Excessive secretion of gastric juice can cause gastric ulcers because the HCl can damage the stomach wall.</p> Signup and view all the answers

What sections make up the small intestine and their respective lengths?

<p>The small intestine consists of the duodenum (25 cm), jejunum (2.5 m), and ileum (3.5 m).</p> Signup and view all the answers

What structures increase the surface area for absorption in the small intestine?

<p>Circular folds, villi, and microvilli increase the surface area for absorption in the small intestine.</p> Signup and view all the answers

What is the function of lacteals in the small intestine?

<p>Lacteals transport lipids to the lymphatic circulation.</p> Signup and view all the answers

Describe the role of segmentation in the small intestine.

<p>Segmentation mixes food back and forth to distribute it and enhance nutrient absorption.</p> Signup and view all the answers

What are the primary transport mechanisms for amino acids and glucose in the small intestine?

<p>Blood capillaries transport amino acids and glucose to the liver.</p> Signup and view all the answers

What role does gastrin play in the digestive process?

<p>Gastrin controls the secretion of gastric juice in the stomach.</p> Signup and view all the answers

What are the two primary sources of lecithin mentioned?

<p>Egg yolk and soya bean.</p> Signup and view all the answers

List two functions of triglycerides and fatty acids in the body.

<p>Source of energy and they provide insulation.</p> Signup and view all the answers

What role do phospholipids play in cellular structure?

<p>They form the bilayer of the cell membrane.</p> Signup and view all the answers

What is one function of cholesterol in the body?

<p>It is a component of cell membranes.</p> Signup and view all the answers

What is vitamin A primarily associated with?

<p>Vision.</p> Signup and view all the answers

Identify one function of sodium in the body.

<p>Osmoregulation.</p> Signup and view all the answers

Why is calcium important for bone health?

<p>It contributes to strong bones and teeth.</p> Signup and view all the answers

What is the main function of iron in the body?

<p>It is a component of hemoglobin.</p> Signup and view all the answers

What role does water play in biochemical reactions?

<p>It serves as a medium for all biochemical reactions.</p> Signup and view all the answers

What is the primary function of saliva in the oral cavity?

<p>It moistens food and aids in digestion.</p> Signup and view all the answers

How does the epiglottis function during swallowing?

<p>It closes the opening of the trachea.</p> Signup and view all the answers

What propulsion mechanism is used in the esophagus?

<p>Peristalsis.</p> Signup and view all the answers

What begins the process of protein digestion in the stomach?

<p>Gastric juice containing pepsin.</p> Signup and view all the answers

What is the function of hydrochloric acid (HCl) in gastric juice?

<p>It converts pepsinogen to pepsin and inhibits bacteria.</p> Signup and view all the answers

What is the significance of the pyloric sphincter?

<p>It regulates the release of stomach contents into the small intestine.</p> Signup and view all the answers

Study Notes

Digestive System Overview

  • The digestive system breaks down food into smaller pieces, delivering nutrients into the bloodstream and eliminating waste.
  • Digestion involves both mechanical (physical) and chemical (enzymatic) processes.
  • Key terms include:
    • Digest: Breaking down into smaller pieces
    • Absorb: Delivering into the bloodstream
    • Enzyme: A biological catalyst speeding up reactions
  • Learning objectives include outlining functions of nutrients, identifying/relating digestive organs to their functions, distinguishing between peristalsis and segmentation, describing both mechanical and enzymatic digestion of food, and outlining the fate of ingested food.

Nutrients

  • Nutrients essential for life include: carbohydrates, proteins, lipids, vitamins, minerals/electrolytes, and water.

Carbohydrates

  • Carbohydrates consist of elements C, H, and O.
  • Carbohydrates are classified by the number of subunits (n):
    • Monosaccharides
    • Disaccharides
    • Oligosaccharides (n = 3 to 10)
    • Polysaccharides
  • Common monosaccharides (6C) include glucose (ATP source), fructose (fruits, soft drinks), and galactose (milk).

Disaccharides

  • Disaccharides are made of monosaccharide subunits.
  • Enzymes digest disaccharides into monosaccharides before absorption.
  • Common disaccharides include sucrose (glucose + fructose), maltose (glucose + glucose), and lactose (glucose + galactose).

Polysaccharides

  • Polysaccharides are formed by many monosaccharides linked by glycosidic bonds.
  • Digested into monosaccharides before absorption.
  • Important polysaccharides include:
    • Starch (plants, main dietary source, digested into glucose)
    • Glycogen (animals, not a major dietary source)
    • Cellulose (plants, indigestible, provides fiber)
    • Chitin (fungi cell wall)

Proteins

  • Proteins consist of elements C, H, N, and O, S.
  • Constructed from chains of amino acids linked by peptide bonds.
  • Twenty common amino acids exist, some essential to a diet.
  • Proteins have many diverse functions, including: enzymes, muscle contraction, hormones, hemoglobin, antibodies, ion channels/carriers/pumps, membrane receptors, and energy source.

Enzymes

  • Enzymes are biological protein catalysts that accelerate reactions.
  • Enzymes have a characteristic of recognizing specific molecules to speed up a reaction. Amylase, for instance, breaks down starch.

Lipids

  • Lipids include triglycerides (“fats”), fatty acids (saturated and unsaturated), cholesterol, and phospholipids.
  • Triglycerides are made of glycerol and three fatty acids, digested by lipases.
  • Phospholipids consist of glycerol, two fatty acids, and a phosphate group. Lecithin is an example found in egg yolks and soybeans.
  • Functions of lipids include energy sources, cushioning/insulation of organs, components of cell membranes, and precursors of steroid hormones.

Vitamins

  • Vitamins are organic chemicals needed in small quantities for life.
  • Vitamins have diverse functions: A (vision), B complex (coenzymes for enzymes), C (antioxidant, collagen synthesis), D (calcium absorption), and E (antioxidant).

Minerals (Electrolytes)

  • Minerals (ions, electrolytes) are essential for several functions.
  • They include calcium (bones, teeth, muscle and nerve function), sodium (osmoregulation, nerve and muscle function), potassium (nerve and muscle function), iron (hemoglobin component), and phosphorous (ATP, nucleic acids, phospholipids, cell membrane components).

Water

  • Water is the medium for biochemical reactions.
  • Water transports solutes and helps maintain body heat.

Digestive Organs and Accessory Organs

  • Digestive Tract (Hollow Tube):
    • Mouth
    • Pharynx
    • Esophagus
    • Stomach
    • Small intestine (duodenum, jejunum, ileum)
    • Large intestine (colon, caecum, rectum, anus)
  • Accessory Organs:
    • Teeth
    • Salivary glands
    • Pancreas
    • Liver
    • Gall bladder

Mouth (Oral Cavity)

  • Digestion begins in the mouth.
  • Teeth cut, tear, and crush food.
  • Salivary glands secrete salivary amylase which digests starch.

Throat (Pharynx)

  • Common gateway for air and food.
  • The epiglottis prevents food from entering the trachea (windpipe) when swallowing.

Esophagus

  • Muscular tube carrying food from pharynx to stomach.
  • Peristalsis moves food through the esophagus.

Stomach

  • Muscular bag expanding to 20x its original size.
  • Holds up to 2 liters of food and gastric juices.
  • Mixes and churns food with gastric juices.
  • Protein digestion begins.
  • Pyloric sphincter releases small amounts of stomach contents into small intestine.
  • Gastric juice components include mucous, HCl, pepsinogen (activated to pepsin), and hormones (e.g., gastrin).

Small Intestine

  • Major site for digestion and absorption.
  • Divided into three sections: duodenum, jejunum, and ileum.
  • Increased surface area through circular folds, villi, and microvilli.
  • Digesting all food classes.
    • Carbohydrates: Starch and carbohydrates and broken down by amylases, disaccharidases (maltase, sucrase, lactase).
    • Proteins: Pepsin inhibited by alkaline pancreatic juice, pancreatic protease, Peptidases break down polypeptides.
    • Fats: Bile emulsifies fats, pancreatic lipase digests fats.

Large Intestine

  • Absorbs remaining water, vitamins, and minerals.
  • Eliminates indigestible material as feces.
  • Colon houses symbiotic bacteria that aid in digestion.

Accessory Organs (Pancreas, Liver, Gall Bladder)

  • Pancreas: Secretes alkaline pancreatic juice (amylase, protease, lipase) into small intestine and bicarbonate which neutralizes the stomach acid.
  • Liver: Produces bile (emulsifies fats), detoxifies substances, and stores glycogen.
  • Gall Bladder: Stores bile secreted by the liver, releases it into the duodenum of small intestine for fat emulsification.

Food Digestion and Absorption

  • Physical digestion: Chewing, mixing, churning, segmentation, and emulsification.
  • Chemical digestion: Amylases, disaccharidases, proteases, and lipases.

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Digestive System Notes PDF

Description

This quiz covers the essential functions and processes of the digestive system, focusing on the breakdown of food and nutrient absorption. Students will also learn about key terms associated with digestion, including enzymes and different types of carbohydrates. Prepare to identify digestive organs and their roles in the digestive process.

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