1. Aim: How do cells of the body communicate? 1.2j Receptor molecules play an important role in the interactions between cells. Two primary agents of cellular communication are hormones, and chemicals produced by nerve cells, neuroreceptors. If nerve or hormone signals are blocked, cellular communication is disrupted and the organism’s stability is affected.

2. Cell Communication

3. Endocrine Glands produce Hormones (chemicals)

4. Hypothalamus The hypothalamus makes hormones that control the pituitary gland. In addition, it makes hormones that are stored in the pituitary gland. Pituitary gland The pituitary gland produces hormones that regulate many of the other endocrine glands. Parathyroid glands These four glands release parathyroid hormone, which regulate the level of calcium in the blood. Thymus During childhood, the thymus releases thymosin, which stimulates Tcell development. Adrenal glands The adrenal glands release epinephrine and nonepinephrine, which help the body deal with stress. Pineal gland The pineal gland releases melatonin, which is involved in rhythmic activities, such as daily sleep-wake cycles. Thyroid The thyroid produces thyroxine, which regulates metabolism. Pancreas The pancreas produces insulin and glucagon, which regulate the level of glucose in the blood. Ovary The ovaries produce estrogen and progesterone. Estrogen is required for the development of secondary sex characteristics and for the development of eggs. Progesterone prepares the uterus for a fertilized egg. Testis The testes produce testosterone, which is responsible for sperm production and the development of male secondary sex characteristics Section 39-1 Endocrine Glands

5. Aim: How do hormones promote communication between cells? Ovary (gland) produces estrogen (hormone) Estrogens are a family of related molecules that stimulate the development and maintenance of female characteristics and sexual reproduction

7. Steroids vs non-steroid Text pg 999 How are they different?

8. Steroid Hormone Target cell membrane mRNA Cytoplasm Protein synthesis Altered cellular function Receptor Hormone- receptor complex Nucleus DNA Nonsteroid hormone (first messenger) Receptor Target cell membrane cAMP (second messenger) Enzyme activities Altered cellular function Cytoplasm Nucleus Hormone Action Section 39-1

9. Heating system turns on Thermostat senses temperature change and switches on heating system Thermostat senses temperature change and switches off heating system Room temperature decreases Section 35-1 Examples of Feedback Inhibition A home heating system uses feedback inhibition to maintain a stable, comfortable environment within a house

10. Beta cells release insulin into the blood Body cells absorb glucose Blood glucose level decreases Homeostasis: Normal blood glucose level Blood glucose level decreases Alpha cells release glucagon into blood Liver converts glycogen to glucose Blood glucose level increases Liver converts glucose to glycogen Figure 39–10 (Text) Actions of Insulin and Glucagon – Feedback Section 39-2

11. How does a Feedback Mechanism work to control Blood Pressure ?

12. Neurons also communicate by producing chemicals Nervous System Nerves are made up of Neurons For communication between neurons to occur, an electrical impulse must travel along the nerve.

13. Information from one neuron flows to another neuron across a synapse All messages are passed between connected neurons in the form of chemicals called neurotransmitters (acetylcholine)

14. Neurons in the brain also communicate with chemicals Serotonin, Histamine, Dopamine, Norepinephrine and Epinephrine

15. Homeostasis is disrupted by paralysis Discuss with your partner what happens to cell communication when paralysis occurs Give an example of what can cause paralysis.