Final bits on digestion

We finished up the small intestine and reviewed the rugae of the stomach (these are the folds that expand when food is eaten and help with mechanical digestion in the stomach). Side note: The stomach can actually absorb aspirin and alcohol.


We also discussed how pepsin in the stomach is a positive feedback loop. Pepsin is an enzyme in the stomach that breaks down proteins into "medium size" molecules called peptides (what do you think pepsin's optimal pH is?). These peptides in turn trigger the production of more pepsin thereby speeding up the digestion of the larger protein molecules (Why is this important?).

After we leave the small intestine where food is completely broken down and absorbed (this happens near the end), we move into the colon (or large intestine). The structure of the colon is shorter but with more diameter than the SI. In this organ, water is absorbed into the bloodstream via capillaries. This causes the waste to become bulkier. (why wait until the end to absorb water?). The bile that was provided by the liver to the small intestine, causes the waste to turn brown when the water is taken out.

Why is fiber important?

From the colon we move into the rectum (storage organ for waste, until it can be released) and finally to the anus where waste exits the body.

Can you identify what organs mechanical and/or chemical digestion occurs? What are the enzymes involved in each stage and where are they made?

Respiratory System

Circulatory and Respiratory systems

 

Today in class, we finished up feedback loops and discussed
Stimulus,
Response
Effector
Receptor
And Control Center
Can you identify each of the parts of a Feedback Loop?

We also started our discussion about the respiratory system. We watched the CrashCourse video and talked about the parts of the respiratory system. Why do we need to take in O2 and get rid of CO2? 

Parts: Mouth/Nose

          Larnyx
          Trachea
          Bronchus (Bronchi)
          Bronchiole
          Alveoli (where gas exchange occurs)


 Why Does Hank discuss the circulatory system with the respiratory system?

 

Body Temperature - Homeostasis

On Saturday we discussed homeostasis and examples feedback loops. 

Negative - thermoregulation (body temperature), Insulin production in the pancreas, 

Positive - Childbirth, blood clotting. 

We also discussed the parts of a feedback loop (see the video below)

Receptor
Effector

Stimulus

Response

You should also have read through the link below:

How does your body regulate temperature game

Below is the video that we watched in class. The second one is another description of body temperature regulation as a negative feedback loop

Homework for Saturday Dec 1

You're homework for saturday is to visit the wesbite Think Bank-Homeostasis and read until you get to 'Play the game'. Please take notes while you are doing so.

Feedback Loops

Our 2nd main topic of the term is Homeostasis. Homeostasis is accomplished mainly via feedback loops. 

Remember that maintaining homeostasis is not JUST responding to changes to your internal and external environments. Sometimes the body needs to 'swing out' of balance to help maintain or 'get back' to homeostasis (ex. running a fever to fight infection, heart rate increasing when running). Can you think of other examples?

Below are 2 videos that explain homeostasis and give examples of the two types of loops:

Negative

Positive

Can you describe the difference between the 2 types and give examples?

Feedback Loops