1. Physiology - Homeostasis
9a. Know how the complementary activity of major body systems provides cells with oxygen & nutrients & removes toxic waste such as CO2
9b. Know how the nervous system mediates communication between different parts of the body & the body’s interactions with the environment.
9c. Know how feedback loops in the nervous & endocrine systems regulate conditions in the body.

2. What is Homeostasis?
The body maintaining a CONSTANT internal environment or steady state, even though things are changing!
Body Systems that are regulated:
Circulatory Respiratory Digestive Nervous

3. Circulatory & Respiratory Systems
The respiratory system brings oxygen to the circulatory system (which distributes it to our body) and removes carbon dioxide from the circulatory system via diffusion

4. Gases Exchanged via Diffusion
Diffusion – flow from an area of high concentration to low concentration
Oxygen goes from our lungs to our heart (blood) where diffusion occurs between oxygen & carbon dioxide, which is brought back to the lungs

5. Digestive System & Circulatory System
Digestive System gives GLUCOSE to the circulatory system
BODY CELLS – use it for cellular respiration to make ATP
FAT CELLS – use it to make (fatty acids) fat
LIVER CELLS – use it to make glycogen (fat)
Cellular respiration:
O2 + Glucose > ATP + CO2 + H2O

6. Regulating Glucose in the Bloood (homeostasis)
HORMONES!
Endocrine System
2 from the PANCREAS!
Insulin
High blood sugar causes it to be released
Causes glucose to go from blood into the cells
This lowers blood sugar
Also causes formation of glycogen in the liver (stored energy)

7. Regulating Glucose in the Bloood
Glucagon
Released when glucose is very low
Not enough glucose for the body…only enough for the nervous system
Causes glycogen to be broken down into glucose
Causes fats to be broken down

8. Diabetes Type 1 Type 2 Insulin Resistance & Deficiency
Insulin Dependent
The body destroys the cells in the pancreas that produce insulin
Must inject insulin & follow a strict diet & exercise routine
Can be genetically predisposed or caused by a virus / chemicals
Insulin Resistance & Deficiency
Genetic
Risk factors: lifestyle factors like excess weight, diet, lack of exercise, high blood pressure
Symptoms may not show for many years and, by the time they appear, significant problems may have developed

10. Other Source of Energy Protein
Amino acids are an energy source for our body
Must be deaminated, which forms ammonia (a toxin) that is excreted by the kidneys as urea (pee)

11. Feedback Loops (Nervous & Endocrine)
Used to regulate body conditions
The presence or absence of hormones act as a trigger
Leptin
Carried by blood to the brain where it inhibits appetite
Decrease in fat reserves causes leptin to decrease causing us to feel hungry