Warm-Up!!! 4/23 Cell Cycle! Label #s 1-5 and can you remember what happens in S phase of the cell...

Warm-Up!!! 4/23Cell Cycle!

Label #s 1-5 and can you remember

what happens in S phase of the cell cycle?

Warm-Up!!! 4/23Cell Cycle!

1 – Prophase2 – Metaphase3 - Anaphase4 - Telophase5 - Cytokinesis

Warm-Up!!! 4/23Cell Cycle!

S Phase = DNA is

copied!!!

Warm-Up!!! 4/23Cell Cycle!

G1 = cell growth

G2 = cell prepares for division (mitosis)

Warm-Up!!! 4/23Cell Cycle!

Interphase = Any time cell

is not dividing!

Basics of the Human Body!!!

Levels of OrganizationThe levels of organization in the human

body are as follows:

CellsTissuesOrgans

Organ SystemsOrganism

Levels of OrganizationExample:

Cells -NeuronTissues -Nervous TissueOrgans -BrainOrgan Systems -Nervous SystemOrganism -Human

HomeostasisEach cell in the human body is both an independent unit and a

part of a larger community.

Each of your 100 trillion cells must work together at all times to

keep the body functioning correctly.

Homeostasis

Short definition: the body’s ability to maintain a

constant internal environment despite external changes.

Homeostasis

For example: when you go outside on a really hot day

your internal body temperature does not rise –

the body takes action to keep you at a constant 98.6

degrees.

HomeostasisThe body MUST always maintain

homeostasis or risk harm:

Homo = Same

Stasis = constant

Homeostasis

A perfect non-living example of homeostasis:

The air conditioner inyour house.

Homeostasis1. Air conditioner set at 75

degrees. 2. If the temp. warms to 76 a

sensor notes this and turns the air on.

3. When the sensor detects the temp has fallen back to 75 it shuts

the air off.4. A constant internal environment

has been kept.

HomeostasisThis kind of response is called

Negative Feedback.

That is, when a systems pushes things in the opposite direction

in response to some kind of change.

Negative Feedback!

HomeostasisThe body uses sorts of negative

feedback loops to maintain homeostasis.

Example: maintenance of a stable internal body

temperature.

HomeostasisBody’s temperature sensor is the

Hypothalmus deep inside the brain.

So, the hypothalamus is probably part of which of the 11 body

systems?

Homeostasis:1. Body temperature drops to 97

degrees.2. Nerve cells of the hypothalamus

sense the temperature change.

3. Hypothalamus releases chemicals that tell muscle cells

to ‘shiver’ to create heat.

Homeostasis:

4. Muscles produce heat that warms the body back to 98 degrees.

5. The nerve cells of the hypothalamus detects this

increase in temperature and stops releasing the chemical that tells

the muscles to shiver.

Negative Feedback!

Conclustion:Using negative feedback loops the

body can keep its internal environment within very stable limits (we call this maintaining

homeostasis).

If this process is not working properly…..you have the potential

for some serious bodily harm.