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.
Do now: label the endocrine glands.

2. Cell Communication

3. Endocrine Glands produce Hormones (chemicals)
What are the hormones produced by these glands?

4. Aim: What are the target tissues for various hormones?

5. Endocrine Glands Section 39-1 Hypothalamus Pineal gland
The hypothalamus makes hormones that control the pituitary gland. In addition, it makes hormones that are stored in the pituitary gland.
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.
Pituitary gland
The pituitary gland produces hormones that regulate many of the other endocrine glands.
Pancreas
The pancreas produces insulin and glucagon, which regulate the level of glucose in the blood.
Parathyroid glands
These four glands release parathyroid hormone, which regulate the level of calcium 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.
Thymus
During childhood, the thymus releases thymosin, which stimulates Tcell development.
Testis
The testes produce testosterone, which is responsible for sperm production and the development of male secondary sex characteristics
Adrenal glands
The adrenal glands release epinephrine and nonepinephrine, which help the body deal with stress.

6. Hormones travel in circulatory system to target organs
Ovary (gland) produces estrogen (hormone)
Estrogens are a family of related molecules that stimulate the development and maintenance of female characteristics and sexual reproduction

8. Aim: What is feedback control…How does it maintain homeostasis?
Work in your groups to discuss feedback
Pg. 1000

9. Figure 39–10 (Text) Actions of Insulin and Glucagon – Feedback
Section 39-2
Beta cells release insulin into the blood
Body cells absorb glucose
Blood glucose level increases
Liver converts glycogen to glucose
Blood glucose level decreases
Homeostasis: Normal blood glucose level
Feedback inhibition or mechanism is the process by which the product of a system shuts down the system or limits its operation.
Feedback controls maintain homeostasis.
The top half of the flowchart shows what happens when the level of glucose in the blood increases.
The bottom half shows what happens when the level of glucose in the blood decreases.
Normally, blood glucose levels stay within narrow limits throughout the day: 4 to 8mmol/l. But they are higher after meals and usually lowest in the morning. For reasons that are not well understood, when very high levels of blood glucose are present for years, it leads to damage of the small blood vessels.
Blood glucose level increases
Blood glucose level decreases
Liver converts glycogen to glucose
Alpha cells release glucagon into blood

10. Examples of Feedback Inhibition
A home heating system uses feedback inhibition to maintain a stable, comfortable environment within a house
Section 35-1
Thermostat senses temperature change and switches off heating system
Heating system turns on
Room temperature decreases
For the body to maintain a stable temperature, there must be a balance between heat production and heat loss. The hypothalamus monitors the temperature of organs in the body’s core. If the nerve cells sense that the core temperature has dropped much below 37 degrees C the hypothalamus produces chemicals that signal cells throughout the body to speed up their activities, causes the inner core body temperature to rise.
Thermostat senses temperature change and switches on heating system

11. Feedback Mechanism to control Blood Pressure
The regulation of blood pressure is highly complex, involving multiple mechanisms that act in both the short term and the long term. Here is a simple scheme in which two processes act together to exert control over blood pressure. Vasodilation and vaso constriction refer respectively to the expansion or narrowing of the diameter of the arterioles

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

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.
Synapse is the junction between neurons (space). How can electricity (flow of electrons) travel through empty space?
It cannot. Therefore, the body developed a mechanism of providing a chemical compound that can transfer electrons. This is communication between cells.

14. Neurons in the brain also communicate with chemicals
In the central nervous system (CNS), biogenic amines control and modulate various functions, including cardiovascular homeostasis, circadian rhythms, emotional states, endocrine secretion, sexual behavior, thermoregulation, as well as learning and memory.
In humans, the etiology of several neural diseases (mental illness) has been linked to impaired biogenic amine signaling
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.