Download Study Guide -- Homeostasis and Human Body Systems

The Study Guide Below has some overall information about how the
systems work together. The following link is to a Biology Library
section on the systems. It is fairly condensed and includes some
good pictures. You have to select the hyperlinks to view more
pictures. Animal Organ Systems
Here’s a link on STEM Cells: Stem Cells
Study Guide -- Homeostasis and Human Body Systems
Here are the key topics for this test:
1. What is homeostasis and how do our various organ systems work together to maintain it?
2. What role does diffusion play in how the human body systems work?
3. What role does surface area to volume ratio apply in how human body systems work?
4. What role do enzymes play in how human body systems work?
5. What role do hormones play in how human body systems work?
1. Homeostasis
Homeostasis is the process by which the organ systems work together to maintain optimal conditions fo
the chemical reactions our cells need to perform.
YOU SHOULD BE ABLE TO TALK ABOUT HOW AT LEAST TWO BODY SYSTEMS WORK TOGETHER TO MAINTAI
HOMEOSTASIS.
2. Diffusion
Diffusion is the process where stuff goes from where there is more to where there is less. This is how the
things your cells get what they need and get rid of what they don't need. Here are some examples:
a. In the digestive system, there are more nutrients inside the intestines than in the blood vessels
that run through the intestines. So, the nutrients move from where there is more (in the intestines) to
where there is less (in the blood). The blood then carries the nutrients to the rest of the body.
b. In the respiratory system, there is more oxygen in the alveoli (the liitle sacs that make up the
lungs) than in the blood vessels that run alongside them. So, the oxygen moves from where there is mo
(in the alveoli) to where there is less (in the blood vessels). In the case of carbon dioxide, there is more
the blood vessels than in the lungs, so the carbon dioxide also goes from where there is more to where
there is less.
c. In the excretory system, there is more waste in the blood going through the kidneys than in th
kidneys themselves. So the waste products go from where there is more (blood) to where there is less
(kidneys). This is how our bodies work to remove waste.
3. Surface Area to Volume Ratio
This is a big phrase that mean cramming more stuff into the same space.
If I can cram more stuff in the same amount of space, I have more surface for diffusion to happen.
Here's an example. At the end of all of the tubes of your lungs are little sacs called alveoli. These sacs a
really tiny. But they increase the surface of your lungs to a space of about 3 football fields, which mea
that lots of diffusion of oxygen can happen in a relatively little space.
The same principle applies to each of the body systems. Here are some examples:
a. digestive system -- the villi in the small intestine increase the amount of surface so that many more
nutrients can be absorbed in the same amount of space.
b. endocrine system -- glands are typically small. They make up for this by having lots of folds in the insi
which gives them more surface where they can make hormones.
c. circulatory system -- the smallest blood vessels are called capillaries. They are only a few cells thick,
which means that they can everywhere that the body's cells are.
4. Enzymes
Enzymes are chemicals that speed up chemical reactions.
Enzymes are proteins.
Enzymes are specific to a particular chemical reaction.
Enzymes are not used up by the chemical reactions in which they are used.
The shape of enzymes matters. If we change the shape, we change (or ruin) their function. Heat or pH
will change the shape of enzymes. This is why fever is so bad for us.
Look over the animation we showed in class about how enzymes work:
Enzyme Activity
5. Hormones
Hormones are chemical messengers that help our bodies respond to changes in the internal and
external environment.
Hormones are made by organs called glands. There are many glands throughout the body. The gland
each make different hormones. The pituitary gland (which is found in the brain) is called the master
gland.
Here is a picture of the glands. You DO NOT have to memorize all of these glands.. I just want you to se
where they are in your body.
Hormones tell cells to do something or to stop doing something.
Hormones work by negative feedback loops.
The shape of hormones matters. Only target cells (cells on which the hormones work)
that have receptors with the right shape will respond to a particular hormone. All other
cells will just ignore it.
Here is a picture which shows how target cells work:
Only target cells with the right receptors can respond to the hormone because the
shape fits. Otherwise, the hormone does not work on that cell.
Here is a picture that shows how hormones work:
Here's the story:
The brain registers information about changes to the internal or external environment.
This information triggers glands to make certain hormones which cause changes to cells
that respond to the perceived change.
The change in the cells' function is registered by the brain. When the proper condition in
the body is restored, the hormones stop. Otherwise the process continues until the
change is responded to.
Adopted from:
8th Grade Living Environment
Mr. Ardito's Classes
Edit this page (if you have permission) |
Google Docs -- Web word processing, presentations and spreadsheets.