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Human Body Systems I. Organization of the Body (Review) A. Cells  Basic unit of structure and function B. Tissues  Group of cells that perform a single.

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Presentation on theme: "Human Body Systems I. Organization of the Body (Review) A. Cells  Basic unit of structure and function B. Tissues  Group of cells that perform a single."— Presentation transcript:

1 Human Body Systems I. Organization of the Body (Review) A. Cells  Basic unit of structure and function B. Tissues  Group of cells that perform a single function (e.g. epithelial, connective, nervous, muscle) C. Organs  Different types of tissues that work together to perform a closely related function (e.g. eye, liver, lungs) D. Organ Systems  Group of organs that perform closely related functions (e.g. circulatory, respiratory, digestive)

2 II. Homeostasis A.Definition: the process by which organisms keep internal conditions relatively constant despite changes in their external environments B.Requires the integration of all organ systems at the same time C.Nervous system in conjunction with the endocrine system (hormones) is responsible for this integration

3 Room temp. rises Thermostat Room Temperature Drops Signals Section 35-1 Examples of Feedback Inhibition III. Maintaining Homeostasis A.Negative feedback – your body’s response results in decreasing the effect of the stimulus (e.g. body temperature) Sensed by Heater to turn on

4 B. Positive feedback – your body’s response results in an increase in the effect of the stimulus, (e.g. the flight-fight response)

5 Nervous System  Recognizes and coordinates the body’s response to changes in its internal and external environments. I. General Functions of the Nervous System A. Sensory input – vision, hearing, balance, smell, taste, and touch B. Motor output – muscle contraction and movement C. Memory and integration of information

6 II.Organization of the NS A.Central N.S. 1. Brain 2. Spinal Cord B. Peripheral N.S. 1. Somatic N.S. 2. Autonomic N.S. a. Sympathetic b. Parasympathetic

7 III. Division of Labor A. Central Nervous System (CNS)  Control center of the body that relays messages, and processes and analyzes information 1. Brain a. Cerebrum – largest region; right and left hemispheres that are connected by corpus callosum; voluntary activities and higher brain functions b. Cerebellum – located at the lower back part of brain; coordination and balance Nervous System

8 c. Brain stem – connects the brain and spinal chord; two regions: pons and medulla oblongata, control breathing, heart rate and swallowing d. Thalamus and hypothalamus - between brain stem and cerebrum Thalamus: relay station for sensory info Hypothalamus: most important homeostatic site; hormones, body’s thermostat, fight or flight, thirst, hunger, reproduction Nervous System

9 Pons Pituitary gland Hypothalamus Cerebrum Medulla oblongata Spinal cord Cerebellum Pineal gland Thalamus Draw Fig. 35-9: The Brain

10 2. Spinal Cord  Two main fxns: 1. Processing of simple responses to certain stimuli (reflexes) 2. Carries info to and from brain to body Nervous System

11 B. Peripheral Nervous System (PNS)  Receives information from the environment and relays to and from CNS and sensory, motor and gland cells Nervous System

12  Two divisions: 1. Sensory - Made of sensory neurons that bring info to the CNS 2. Motor - Made of sensory neurons that convey info from the CNS; two subdivisions a. Somatic (voluntary): respond to external stimuli b. Autonomic (involuntary): respond to internal stimuli w/the parasympathetic and sympathetic divisions 1) Sympathetic ↑energy consumption 2) Parasympathetic ↓energy consumption

13 Nervous System Flow Chart Sympathetic (activities that increase energy consumption) Parasympathetic (activities that gain and conserve energy)

14 Nervous System IV. Neurons (Nerve Cells)  Specialized cells that carry electrical signals called impulses (Draw Fig. 35-5; pg. 897) A. 3 Types of Neurons: 1. Sensory – carry impulses from the sense organs to the spinal cord and brain 2. Motor – carry impulses from brain and spinal cord to muscles and glands 3. Interneurons – Connect sensory and motor neurons and carry impulses between them

15 Nervous System B. Anatomy of a Neuron 1. Cell Body  Largest part of the neuron  Contains the nucleus and most of the cytoplasm  Metabolic activity takes place in the cell body Cell Body

16 Nervous System 2. Dendrites  Carry impulses from the environment or other neurons to the cell body

17 Nervous System 3. Axon  Long fiber that carries impulses from the cell body  Ends in axon terminals that contain vesicles for neurotransmitters

18 Nervous System 4. Myelin Sheath  Insulates the axon  Gaps in the myelin sheath allow an impulse to jump from node to node, thus increasing its speed

19 yellow Which part of the neuron is yellow? Which parts are blue?

20 V.The Nerve Impulse A. The Resting Neuron 1. At rest, the outside of the cell has a net positive charge and the inside has a net negative charge. This charge difference is called the resting potential. (-70mVolts, about 5% of the voltage in AA battery)

21 2. The charge difference is created by active transport of ions across the cell membrane via the sodium-potassium pump. 3. Sodium ions (Na+) are pumped outside the cell and potassium (K+) ions are pumped into the cell. A.The Resting Neuron (cont)

22 B.The Moving Impulse 1. An impulse begins when a neuron is stimulated by the axon of another neuron or by the environment. 2. Na+ pores open and the flood of Na+ ions makes the inside positive. _ + + _

23 3. This reversal of charges, from negative to positive is called a nerve impulse, or an action potential. 4. As the impulse passes, K+ pores open and K+ flows out which restores the resting potential (charge difference) + _ + _ B.The Moving Impulse (cont)

24 5. How do things get back to the original condition? The sodium potassium pump kicks in. 6. The minimum level of a stimulus that is required to activate a neuron is called the threshold. B.The Moving Impulse (cont)

25 Nerve Impulse Summary

26 C.Nerve Impulse Pathway Overview 1. Impulse is received by the dendrites from the environment or another neuron, then gets rapidly channeled through the cell body to the axon 2. Axon branches out into axon terminals, which contain tiny vesicles filled with neurotransmitters, which are chemicals used by a neuron to transmit an impulse to another cell. (e.g. acetylcholine, serotonin, dopamine and adrenalin). 3. Vesicles release neurotransmitters into the open space between neurons called the synapse.

27 C.Nerve Impulse Pathway (cont) 4. The neurotransmitters diffuse across the synapse and attach themselves to receptors on dendrite of neighboring cell Vesicle Axon Axon terminal Synaptic cleft Neurotransmitter Receptor Dendrite of adjacent neuron Direction of Impulse

28 Nervous System VI. Reflexes  Reflexes are automatic responses to stimuli  Controlled by 5-part reflex arc: 1. Sensory receptors on finger reacts to stimulus (heat) 2. Impulse is carried to the spinal cord by a sensory neuron 3. In the spinal cord, the impulse is transferred by an interneuron to motor neuron 4. Motor neurons conducts the impulse to an effector (arm muscles) 5. Effector responds to the impulses by contracting (hand gets pulled away from the heat)

29 Nervous System VIII. The Senses 5 General Sensory Receptors: pain, thermo-, mechano-, chemo- and photoreceptors. Where do you think these different types of receptors are found and what is their function? A. Vision B. Hearing and Balance C. Smell and Taste D. Touch

30 Nervous System IX. Nervous System Disorders A. Migraine Headaches – caused by change in serotonin levels? (affected by caffeine, estrogen, certain foods) B. Parkinson’s –caused by damage to dopamine transmitters; causes uncontrollable shaking, no cure C. Tay-Sachs –lack enzyme to break down fatty deposits in the brain; neurological deterioration; death by age 4-5 D. Dementia - damaged brain cells caused by injury or disease (Alzheimer’s); memory loss and personality change.

31 Nervous System X. Drugs and the Nervous System A. Stimulants  Accelerate HR, BP, and breathing rate  Increases the release of neurotransmitters; leads to release of energy and feeling of well-being  When effect wears off, brain’s supply is depleted 1. Caffeine 2. Cocaine 3. Methamphetamines

32 Nervous System B. Depressants  Slow down HR, lower BP and breathing rate, relax muscles and relieves anxiety 1. Alcohol 2. Marijuana 3. Sleeping Pills

33 Used to increase alertness, relieve fatigue Used to relieve anxiety, irritability, tension Used to relieve pain Stimulants Depressants Opiates Amphetamines Barbiturates Tranquilizers Morphine Codeine Increase heart and respiratory rates; elevate blood pressure; dilate pupils; decrease appetite Slow down the actions of the central nervous system; small amounts cause calmness and relaxation; larger amounts cause slurred speech and impaired judgement Act as a depressant; cause drowsiness, restlessness, nausea Section 35-5 Commonly Abused Drugs Drug TypeMedical UseExamplesEffects on the body Commonly Abused Drugs


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