SBI 3U- THE HUMAN DIGESTIVE SYSTEMS

AND DISORDERS

Zachary Lamacraft

Overview/Agenda Curriculum expectations Introduction of human systems Enzymes Ingestion-activities Stomach and Digestion- with a case study Small intestine and pancreas- video and activity

examples Accessory organs Absorption- activity examples Homeostasis Energy, Nutrients and Minerals

Curriculum Expectations Specific Expectations E1.1 evaluate the importance of various technologies, including Canadian

contributions, to our understanding of internal body systems (e.g.,endoscopes can be used to locate, diagnose, and surgically remove digestive system tumours; lasers can be used during surgery to destroy lung tumours; nuclear magnetic resonance [NMR] imaging can be used to diagnose injuries and cardiovascular disorders, such as aneurysms) [AI, C]

E2.2 perform a laboratory or computer-simulated dissection of a representative animal, or use a mounted anatomical model, to analyse therelationships between the respiratory, circulatory, and digestive systems [PR, AI]

E3.2 explain the anatomy of the digestive system and the importance of digestion in providing nutrients needed for energy and growth (e.g., the body’s mechanical and chemical processes digest food, which provides the proteins needed to build muscle, and the fibre, water, vitamins, and minerals needed to regulate body processes)

E3.4 describe some disorders related to the respiratory, digestive, and circulatory systems (e.g., asthma, emphysema, ulcers, colitis, cardiac arrest, arteriosclerosis

Human Systems

Organs: groups of different tissues that specialize to carry out specific or particular functions.

Organ systems: a group of organs that have related functions

Important to note that several organ systems interact and depend on each other to function

Importance of Digestion/the Digestive System

Heterotrophs: organisms that must consume organic compounds to survive

Organic compounds (carbohydrates, fats, proteins, minerals and vitamins) are digested/ broken down in gastrointestinal tract and then absorbed and transported

Supplies body with energy and raw materials for synthesis of chemical compounds

Enzymes in Digestion Recall enzymes are proteins that increase

the rate at which biochemical reactions occur The enzymes in the digestive system are

hydrolytic : use water to breakdown various molecules

Two factors effect digestive enzymes: -Temperature -pH

Generally increase in temperature= increase enzyme activity

Enzymes work in specific pH ranges

Enzyme ActivityFigure 1: Effect of temperature on human enzymes

Figure 2: Effect of pH on digestive enzymes

blue= pepsingrey= amylaseGreen- trypsin

Discussion Question

Question/Reflection for Student:“Why do most human enzymes have efficiency peaks at 37oC

What impacts do cold and heat have on our body functioning?

Why is it dangerous to have a fever? What may happen to our enzymes?

Recap: Physical vs. Chemical Digestion Physical/Mechanical: is the act of

breaking down food using teeth, beaks or other structures in many animals as well as contractions of the stomach

Chemical: enzymes and water to break down food so that it can eventually be absorbed by body cells

4 Main Processes of The Digestion System 1. Ingestion 2. Digestion 3. Absorption 4. Egestion/ or Elimination

Ingestion

Saliva- Fluid secreted by salivary glands- Contains amylase which breaks down

complex to simpler carbohydrates- Lubricates food to be swallowed- Dissolves food particles- At this point food can be “tasted”

Activities:

Ingestion cont.

Teeth:-incisors: specific for cutting-canine: sharp for tearing-pre-molars: grinding-molars: crushing

Used for mechanical/physical digestion. They are necessary for making food into smaller particles

Ingestion cont.

Esophagus Peristalsis: rhythmic, wavelike

contraction of smooth muscle that moves food through the esophagus

Food formed in a bolus after being broken down by saliva and teeth enters the esophagus

http://www.youtube.com/watch?v=rJS-Kh5wCQU

The Stomach and Digestion- Site of food storage and

protein digestion- J-Shape organ that can store

up to 1.5 L of food- Movement of food in and out

of stomach is regulated by sphincters

- Cardiac sphincter: regulates food from esophagus

- Pyloric sphincter: regulates food from stomach to small intestine

The Stomach and Digestion cont. There are millions of cells that line the wall of

the stomach that secrete many fluids which called collectively called gastric juice

Gastric juice : Hydrochloric acid (HCl) mucus, pepsinogens and other materials

Pepsinogens: enzymes that when exposed to a low pH such as conditions in the stomach, turns into its active form pepsin which is a enzyme the digests proteins

What do we know about HCl?

What stops HCl from burning a hole in your stomach?

Mucus

A protein produced by a layer of epithelial cells that provide a protective coating

It is alkaline in nature which is basic and protects lining of the stomach from both acid from HCl and pepsin from breaking down proteins of stomach lining

However when mucus is destroyed or not being produced…

Disorder: Stomach Ulcer

Ulcer: a lesion along the surface of an organ-when the mucus membrane is destroyed a peptic ulcer can be formed resulting in tissue being burned and an allergic reaction can become stronger resulting in blood vessels breaking down

Heliobacter pylori

Stomach Disorders: Ulcers cont.

Case Study Have students in pairs or small groups

uncover this bacteria Heliobacter pylori and other information about ulcers

Prevalence, demographics, how to detect this bacteria, bacterial weight/amount, effects on every day living/side effects, treatment etc. are all topics the students could discover

Could be in the form of a report, or a presentation, or even a jigsaw activity

Small Intestine Introduction Activities

http://www.youtube.com/watch?v=4waSJqOEJts

Easy way to get the students thinking about the small intestine is having 7m of yard, tubing etc. and having it passed around the classroom

After this have them put it in a small box Small intestine is not named small because

of its length rather its diameter!

Small Intestine Cont.

3 parts of the small intestine are the:

Duodenum:- most digestion occurs here

Jejnum: has many folds that continue breakdown and absorption of remaining proteins and carbohydrates

Ileum: less absorption occurs here, unabsorbed particles are pushed through and continued

Digestion in the Small Intestine

How is the small intestine protected if HCl and pepsin- soaked food is sent to it from the stomach?

Small Intestine and Pancreas Interaction

Small Intestine and Pancreas Interaction

Liver and Gall Bladder: Role in Digestion

Absorption and Large Intestine

Colon is largest part of large intestine stores waste so that water as well as some inorganic salts, minerals and vitamins can be absorbed

There are several bacteria in the large intestine such as types of E.coli that can synthesize vitamins B and K

Cellulose is a carbohydrate that cannot be broken down by humans but provides bulk

Absorption: Villi, Microvilli and Lacteals Villi: small finger-like projects that

extend into the small intestine which increase surface area for absorption.

Microvilli: are a microscopic projection on cell membrane

Lacteals: are small vessels that transport fat to the circulatory system

Homeostatic Control in Digestion

Build a Body: SPONGELAB Biology

Food energy

In Canada energy is measured in joules (J) or kilojoules (kJ)

One calorie = 4.18 JOne kcal = 4.18kJ

Basal metabolic rate: the minimum amount of energy that a resting person needs to maintain life processes

Daily Energy Requirements

Calculating Energy Requirements

There is a way to calculate energy requirements. The equation is

Energy required for 1 day= energy factor x body mass (kg) x time (24hr)

Energy required for an activity= energy factor x body mass (kg) x time (hr)

Essential Nutrients

Vitamins: organic molecules needed in trace amounts for normal growth and metabolic processes

Minerals: elements required by the body. There are inorganic

Nutrients

Minerals