THE JOURNEY OF THE DIGESTIVE SYSTEM LAB (online)

Objectives:

1.       View the digestive system in action

2.       Investigate the action of salivary amylase in yourself

3.       Record information about digestive enzymes and their actions

4.       Answer basic questions about the anatomy and operation of the digestive system

5.       Create a Food Tracker plan for yourself.

Part 1. The Journey of the Digestive System

If you haven’t already, watch "The Journey of the Digestive System” at https://www.youtube.com/watch?v=e3O1AdlC8bI (5:08).

Part 2. Salivary Amylase and Other Digestive Enzymes

The digestion of a carbohydrate such as starch begins in the mouth where amylase produced by salivary glands is mixed with saliva.  Amylase is also produced by the pancreas and secreted into the duodenum.  In the presence of amylase, starch (a polymer of glucose) is hydrolyzed into the disaccharide maltose (a sweet sugar).  Maltose is later digested in the small intestine to glucose where it is absorbed.  Maltose, glucose, and other monosaccharides are known as reducing sugars. 

This can be demonstrated in a simple taste test.

1.       Place a crushed, salt free cracker or a small piece of bread or tortilla on the surface your tongue.  If salivary amylase breaks down the starch in the cracker to maltose, it should begin to taste sweet.

2.       Record the amount of time it takes to begin to sense a sweet taste instead of a starchy taste.

TIME: 1 min 15 seconds: it took me twice to taste the sweet, the first time it just got mushy so the second time I put it further back on my tongue and was able to taste the sweet.

  

Complete this chart.

Enzyme                                                  Producing Organ                     Site of Action                          Substrate(s)

Salivary amylase	Salivary Glands	Mouth	Polysaccharides
Trypsin	Pancreas	Small Intestine	Proteins
Lipase	Pancreas	Small Intestine	Triglycerides
Pepsin	Stomach	Stomach	Proteins

Questions

1.       Name the end molecules of digestion for each of the following types of food. In other words, what smaller pieces is each hydrolyzed into to be made available to the body?

a.       Proteins: The end molecule of proteins is Amino Acids.

b.      Carbohydrates: The end molecule of carbohydrates is monosaccharides.

c.       Fats: The end molecule of fats is chylomicrons.

2.       Describe the process by which fats enter the blood.  Bile salts emulsify lipids large fat droplets into smaller droplets so that lipases can digest the fats into fatty acids and monoglycerides. The fatty acids and monoglycerides dissolve in micelles composed of bile salts and lecithin. Micelles near the cells surface release their fatty acids and monoglcerides, which then diffuse across the cell membrane. In the cell the fatty acids and monoglycerides are re-synthesized to triglycerides and coated protein. The protein-coated yriglycerides are called chylomicrons. The chylomicrons exit the cell and enter a lacteal for transport to the blood. (Human Biology Concepts and current issues)

Part 3. Food Tracker

Visit this site https://www.supertracker.usda.gov/https://www.supertracker.usda.gov/and choose one of the six options on the homepage, Food-a-pedia, Food Tracker, Physical Activity Tracker, My Weight Manager, My Top 5 Goals, or My Recipe.

Participate in the activity and write a one paragraph description of what you did and your opinion of the activity.

I chose my weight manager as my activity.  I picked the maintain weight category to help me keep my weight as it is. After entering my information it gave me a routine of exercise and calories I should have on a daily basis.  I found it was interesting that I do not even eat close to the calories it showed I should be eating on a daily basis to maintain my weight. It also showed me the amount of food I should have per food category. I think this is a great tool for anyone who is looking at losing weight or just maintaining their weight.

NERVOUS SYSTEM AND NEURON MODELING v.2 (online)

As usual, please write responses in complete proper sentences.

Objective

Describe the structure of neurons by constructing and labeling models

Introduction

The brain is made up of billions of individual nerve cells (neurons). Understanding the anatomy of a neuron is key to appreciating its functioning along with the functioning of the entire nervous system, including the brain.

Neurons are the oldest and longest cells in the body! You have many of the same neurons for your whole life. Neurons can be quite large, such as corticospinal neurons (extending from motor cortex to spinal cord) or primary afferent neurons (extending from the skin into the spinal cord and up to the brain stem).

One way to classify neurons is by the number of extensions that extend from the neuron's cell body (soma).

·         Bipolar neurons have two processes extending from the cell body (examples, retinal cells, olfactory epithelium cells).

·         Unipolar cells have two axons rather than an axon and dendrite. One axon extends centrally toward the spinal cord; the other axon extends toward the skin or muscle.

·         Multipolar neurons have many processes that extend from the cell body. However, each neuron has only one axon (examples, spinal motor neurons, pyramidal neurons, Purkinje cells).

Neurons can also be classified by the direction that they send information.

·         Sensory (or afferent) neurons: send information from sensory receptors (e.g., in skin, eyes, nose, tongue, ears) TOWARD the central nervous system.

·         Motor (or efferent) neurons: send information AWAY from the central nervous system to muscles or glands.

·         Interneurons: send information between sensory neurons and motor neurons. Most interneurons are located in the central nervous system.

A neuron has four basic parts.

·         Dendrites - Extensions from neuron cell bodies that take information to the cell body. Dendrites usually branch close to the cell body.

·         Cell body (soma) - the part of the cell that contains the nucleus.

·         Axon - the extension from the neuron cell body that takes information away from the cell body. A single axon projects out of the cell body.

·         Axon terminal - end part of an axon that makes a synaptic contact with another cell.

What is inside of a neuron? All of the organelles in a typical cell, although some have specialized names.

A reflex arc involves transmission of a nervous impulse or message from sensory receptors to the spinal cord and back to muscles. Later, the message also reaches the brain for interpretation. Reflexes and spinal cord messages travel faster than the messages to the brain. That is why reflexes are defined as involuntary reactions. A reflex arc involves sensory, motor, and interneurons as well as the spinal cord.

Part 1 Modeling Neurons (15 points)

Materials

• Sheets of plain paper, 8.5” x 11”
• Markers or pens
• Neuron parts, see below

Procedure

What can you use to make a model of a neuron? Here are some suggestions. Please do not purchase materials. You can find plenty of items around the house, shop, or yard.

1.       Refer to the figure below and this site for representations of unipolar, bipolar, and multipolar neurons. You will be building models of each.

2.       Find materials. Here are some suggestions.

·         Play dough (recipe on page 3 of lab)

·         Clay

·         Bottle caps

·         Buttons

·         Jelly beans

·         String

·         Colored paper

·         Washers

·         Other things

3.       Plan your first neuron by collecting the organelles and other structures.

4.       On a sheet of paper, build a large cell body on a sheet of paper and add these organelles.

·         Nucleus

·         Nucleolus

·         Golgi

·         Nissl bodies

·         Cytoskeleton

5.       Refer to your text or other references. Cite your sources, even the text book! 

6.       Add the myelin sheath to your model.

7.       Label the four basic parts by writing them on the paper and adding arrows or other ways of designating the parts.

8.       Build the other two types in the same way. All together you will build bipolar, unipolar, and multipolar neurons.

9.       Take a photo of each neuron and add to your blog site.

NEURON

BIPOLAR NEURON

UNIPOLAR NEURON

MULTIPOLAR NEURON

10.   Answer this question. What is a good idea to help remember the directions afferent and efferent neurons sent messages to or from the central nervous system?

 Afferent means inwards or towards and efferent means away.  You first need stimulus in order to get a response. So an easy way to remember is afferent which is stimulus or sensory neurons comes first and efferent is response or motor neurons.