The nervous system and endocrine system communicate between organ systems to maintain homeostasis. The nervous system works quickly using electrical and chemical signals, while the endocrine system works more slowly using chemical signals through the bloodstream. Neurons are specialized cells that receive and transmit electrochemical signals through their dendrites, cell body, and axon. The senses detect internal and external stimuli which are transmitted by the nervous system. The central nervous system interprets this information and communicates with the peripheral nervous system to stimulate responses. The endocrine system produces hormones that influence cells and affect growth, development, and other processes through chemical messengers in the bloodstream.

1. KEY CONCEPT The nervous system and the endocrine system provide the means by which organ systems communicate.

2. The body’s communication systems help maintain homeostasis. A stimulus causes a response. Responses can be chemical, cellular, or behavioral. The nervous and endocrine systems respond to stimuli.

3. The nervous system controls thoughts, movement, and emotion. The endocrine system controls growth, development, and digestion.

4. The nervous and endocrine systems have different methods and rates of communication. The nervous system works quickly, using chemical and electrical signals. interconnected network of cells signals move through cells divided into central nervous system (CNS) and peripheral nervous system (PNS) spinal chord nerves

5. The endocrine system works more slowly. only chemical signals signals move through bloodstream physically unconnected organs receptor target cell not a target cell bloodstream hormone

6. KEY CONCEPT The nervous system is composed of highly specialized cells .

7. Neurons are highly specialized cells. A neuron has three parts. cell body has nucleus and organelles 1 Cell body

8. Neurons are highly specialized cells. A neuron has three parts. cell body has nucleus and organelles dendrites receive impulses 2 dendrites

9. Neurons are highly specialized cells. A neuron has three parts. cell body has nucleus and organelles axon carries impulses dendrites receive impulses 3 axon

10. Neurons have other structures to transmit signals. Schwann cell

11. Neurons have other structures to transmit signals. synapse Schwann cell synapse

12. Neurons have other structures to transmit signals. terminal synapse Schwann cell axon terminal

13. Neurons receive and transmit signals. Resting potential means no signal is being transmitted. more Na + outside of cell more K + inside of cell

14. An action potential is a moving electrical impulse. It is generated by a stimulus. Na + enters, and cell becomes positively charged. K + leaves, and area of positive charge moves. area of detail

15. A chemical signal passes between neurons. Impulse reaches terminal. impulse

16. A chemical signal passes between neurons. Impulse reaches terminal. impulse

17. A chemical signal passes between neurons. Impulse reaches terminal. impulse Neurotransmitters released into synapse. synapse receptor vesicles neurotransmitter

18. A chemical signal passes between neurons. Impulse reaches terminal. Neurotransmitters released into synapse. impulse Neurotransmitters stimulate next cell. synapse receptor vesicles neurotransmitter

19. KEY CONCEPT The senses detect the internal and external environments.

20. The senses help to maintain homeostasis. Senses gather stimuli, and send it to the nervous system. Nervous system responds to stimuli. Pupils shrink when too much light enters the eyes. Goose bumps when cold air touches skin.

21. The senses detect physical and chemical stimuli. The eye contributes to vision. Photoreceptors sense light. Two photoreceptors work together: rod cells and cone cells.

22. The ear contributes to hearing. mechanoreceptors called hair cells bend in response to vibrations

23. Taste and smell use chemoreceptors. Taste uses tongue, and smell uses nose. Chemoreceptors detect chemicals dissolved in fluid.

24. The skin senses touch. Mechanoreceptors detect pressure. Pain receptors detect damaged tissue. Thermoreceptors detect temperature. pain receptor light pressure receptor hair follicle heavy pressure receptor

25. KEY CONCEPT The central nervous system interprets information, and the peripheral nervous system gathers and transmits information.

26. The nervous system’s two parts work together. The CNS includes the brain, brain stem, and spinal cord. The PNS includes four systems of nerves.

27. The CNS and PNS pass signals between one another. Sensory receptor generates impulse. PNS passes impulse to CNS. CNS interprets impulse. CNS passes impulse to PNS. PNS stimulates a response.

28. The CNS processes information. The brain has three parts. cerebrum controls thought, movement, emotion cerebellum allows for balance brain stem controls basic life functions midbrain pons medulla oblongata Brain stem

29. The brain stem has three parts. midbrain controls some reflexes pons regulates breathing medulla oblongata controls heart function, swallowing, coughing midbrain medulla oblongata pons

30. The spinal cord controls reflexes. sensory neuron sends impulse to spinal cord spinal cord directs impulse to motor neuron does not involve the brain interneuron motor neurons sensory neuron

31. The PNS links the CNS to muscles and other organs. The somatic nervous system regulates voluntary movements. The autonomic nervous system controls involuntary, functions sympathetic nervous system: “fight vs. flight” parasympathetic nervous system: calms the body, conserves energy

32. KEY CONCEPT Scientists study the functions and chemistry of the brain.

33. New techniques improve our understanding of the brain . Today, scientists study the brain without surgery.

34. There are three common technologies. CT uses x-rays to view structure. PET detects activity, where glucose is used, in the brain. MRI uses magnetic fields and radio waves to view structure.

35. Changes in brain chemistry can cause illness. Different neurotransmitters relate to different functions. some stimulate impulses some prevent impulses Normal synapse neurotransmitter receptor

36. Abnormal levels of neurotransmitter can cause illness. schizophrenia depression Normal Schizophrenic Depressed

37. Drugs alter brain chemistry. Addiction is the physiological need for a substance. Tolerance occurs when more drug is needed to produce an effect. Drugs might cause desensitization or sensitization. desensitization: more neurotransmitter leads to fewer receptors sensitization: less neurotransmitter leads to more receptors. When the amount of neurotransmitter becomes abnormal, the adjacent neuron adapts.

38. Stimulants cause more action potentials may increase neurotransmitter in synapse may decrease removal of neurotransmitter in synapse cocaine neurotransmitter synapse

39. Depressants cause fewer action potentials. may produce neurotransmitter that prevent impulses may slow release of neurotransmitter that generates impulses

40. KEY CONCEPT The endocrine system produces hormones that affect growth, development, and homeostasis.

41. Hormones influence a cell’s activities by entering the cell or binding to its membrane. Glands are organs of the endocrine system.

42. Hormones are chemical signals that influence cell’s activities. produced by glands travel through the circulatory system affects cells with matching receptors target cell hormone receptor not a target cell bloodstream

43. There are steroid hormones and nonsteroid hormones. Steroid hormones enter the cell. Nonsteroid hormones do not enter the cell. nucleus Chemical reactions Steroid hormone diffuses through the cell membrane Steroid hormone binds to a receptor within the cell. The hormone and receptor enter the nucleus and bind to DNA Steroid hormone causes DNA to make proteins. Nonsteroid hormone binds to receptor on the cell membrane. Receptor stimulates a second messenger with in the cell. Second messenger starts a series of chemical reactions in the cytoplasm. Second messenger reactions activate enzymes. Steroid hormone receptor DNA proteins Non-steroid hormone receptor second messenger activated enzymes

44. Endocrine glands secrete hormones that act throughout the body. There are many glands located throughout the body. Hormones travel through the bloodstream to cells with matching receptors. HYPOTHALAMUS PITUITARY THYROID THYMUS ADRENAL GLANDS PANCREAS FEMALE GONADS :OVARIES MALE GONADS : TESTES

45. The hypothalamus interacts with the nervous and endocrine systems. a structure of both the nervous and endocrine systems produces releasing hormones, sent to pituitary gland The pituitary gland is found below the hypothalamus in the brain. controls growth and water levels in blood produces releasing hormones sent throughout the body The hypothalamus is a gland found in the brain.

46. Releasing hormones stimulate other glands to produce hormones. allow glands to communicate with one another are used in temperature regulation

47. Hormonal imbalances can cause severe illness. Abnormal hormone levels affect homeostasis. Hormonal imbalances might be treated with surgery or medicine. Steroids, a pituitary tumor, or some prescription drugs can make the pituitary overactive and indirectly cause problems.