Nervous & Endocrine Systems

1. Nervous & Endocrine Systems

2. Nervous & Endocrine Systems • To control all the systems toward the single goal of survival… “HOMEOSTASIS” • Both the nervous and endocrine systems work together for this coordination.

3. Homeostasis • Homeostasis • maintaining internal balance in the body • organism must keep internal conditions stable even if environment changes • example: body temperature • humans: • too cold = shiver • too warm = sweat • lizard: • too cold = bask in sun • too warm = hide in shade

4. high low Controlling Body Temperature Nervous System Control Feedback nerve signals brain sweat dilates surfaceblood vessels body temperature brain constricts surfaceblood vessels shiver nerve signals

5. Regulation by chemical messengers • Neurotransmitters released by neurons • Hormones release by endocrine glands endocrine gland neurotransmitter axon hormone carried by blood receptor proteins receptor proteins target cell

6. Types of nerve cells (neurons) 1.sensory neuron (from senses) 2. interneuron (brain & spinal chord) 3. motor neuron (to muscle)

7. Nervous system cells • Neuron is a nerve cell signal direction dendrites cellbody axon signal direction synapse

8. Structure of Neuron (nerve cell) • Cell Body • Dendrites • Could be many • Receive info • Axon • Only 1 per Neuron • Transmit stimulus

9. Structure of a Neuron • Many axons enclosed by Schwann Cells • Surrounded by Myelin Sheath

10. Myelin coating • Axon coated with insulation made of myelin cells • speeds signal • signal hops from node to node • 330 mph vs. 11 mph

11. Signal Transmission • Neuron depolarizes at the site of stimulus • The movement of this depolarization will move the signal down the neuron.

12. Steps in Nerve Impulse Transmission 1. Stimulus makes cell membrane permeable to Na+ ions. 2. Na+ ions diffuse into the neuron changing the membrane potential 3. Cell membrane is depolarized and an action potential is generated. 4. Cell membrane becomes permeable to K+ ions. 5. K+ ions diffuse out of the cell. 6. Cell membrane is repolarized. 8. Concentration of Na+ and K+ reestablished by Na-K pump.

13. Synapse Junction between nerve cells • 1st cell releases chemical to trigger next cell • where drugs affect nervous system synapse

14. Synaptic Transmission • When signal reaches the synaptic cleft (gap) it releases Neurotransmitter • NT Diffuse across cleft to receptor sites on post-synaptic neuron.

15. Central Nervous System (CNS) Peripheral Nervous System (PNS)

16. Nervous System Divisions Central Nervous System (CNS) • Brain • Spinal cord Peripheral Nervous System (PNS) • nerves from senses • nerves to muscles • 12 pair cranial nerves • 31 pair spinal nerves

17. Higher brain • Cerebrum • 2 hemispheres • left = right side of body • right = left side of body

18. Cerebrum specialization Lobes • frontal • speech, control of muscle & emotions • temporal • smell, hearing • occipital • vision • parietal • speech, tastereading parietal frontal occipital temporal

19. Primitive brain • The “lower brain” • medulla oblongata • pons • cerebellum • Functions • basic body functions • breathing, heart, digestion, swallowing, vomiting • homeostasis • coordination of movement

20. Reflex: Simplest Nerve Circuit • rapid response • automated • signal only goes to spinal cord • no higher level processing • advantage • don’t need to think or make decisions about • blinking • balance • pupil dilation • startle

21. Reflex Arc All reflex arcs have at least five parts: • a sensory receptor • an afferent path (sensory neuron) • an integration center (spinal cord: interneuron) • an efferent path (motor neuron) • an effector (ex. muscle contraction)

22. Peripheral Nervous System • Somatic (voluntary) • External environment - sensory • Skeletal muscles – Motor • Autonomic (involuntary) • Internal environment -sensory • For homeostasis

23. Sympathetic vs. Parasympathetic • Autonomic • Sympathetic • Speed up • Emergency • Parasympathetic • Slow down • Mellow out

24. Glands make hormones (chemical messengers) • Travel through blood stream (Ductless glands: endocrine) • To where - Specific target cells

25. Responding to hormones • Lock and key system • hormone fits receptor on “target” cell Target cell Secreting cell non-targetcells can’treadsignal can’treadsignal

26. Glands • Pineal • melatonin • Pituitary • many hormones: master gland • Thyroid • thyroxine • Adrenal • adrenaline • Pancreas • insulin, glucagon • Ovary • estrogen • Testes • testosterone

27. hormones hormones Body Regulation • Nervous system & endocrine systems work together • hypothalamus • “master nerve control center” • communicates with pituitary gland • “master gland” • releases many hormones

28. Thyroid: controls metabolism with thyroxine • The Thyroid and Parathyroid gland control growth and metabolism • Iodine is a component of thyroxine • Hypothyroidism • Goiter • Hyperthyroidism

29. The Adrenal Glands produce the hormone Adrenaline during stressful situations. • Adrenal gland sits on top of the kidney • Controls “fight or flight” response • Superhuman strength with adrenaline

30. High blood sugar • Pancreas makes insulin • Sugar enters the cells • Blood sugar lowered • Low Blood sugar • Pancreas makes • glucagon • Sugar leaves the liver & muscle • Blood sugar is increased Pancreas produces insulin & glucagon to regulate sugar balance

31. pancreas high liver low pancreas liver Endocrine System Control Regulation of Blood Sugar Feedback insulin body cells takeup sugar from blood liver storessugar reducesappetite blood sugar level (90mg/100ml) liver releasessugar triggershunger glucagon

32. Reproductive hormones • Testosterone • from testes • sperm production & secondary sexual characteristics • Estrogen • from ovaries • egg production, preparing uterus for fertilized egg & secondary sexual characteristics