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

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

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

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

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

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

Nervous System Division of Labor Central Nervous System (CNS) Control center of the body that relays messages, and processes and analyzes information Brain Cerebrum – largest region; right and left hemispheres that are connected by corpus callosum; voluntary activities and higher brain functions Cerebellum – located at the lower back part of brain; coordination and balance Corpus callosum is how the left and right lobes communicate. Often cut to treat epilepsy. Left lobe is for right side of body and vise-versa.

Nervous System Brain stem – connects the brain and spinal chord; two regions: pons and medulla oblongata, control breathing, heart rate and swallowing 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 Medulla oblongata: lowest part of the brain,

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

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

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

Nervous System Two divisions: Sensory - Made of sensory neurons that bring info to the CNS Motor - Made of sensory neurons that convey info from the CNS; two subdivisions Somatic (voluntary): respond to external stimuli Autonomic (involuntary): respond to internal stimuli w/the parasympathetic and sympathetic divisions Sympathetic ↑energy consumption Parasympathetic ↓energy consumption Parasympathetic center controls things like digestion and slowing heart to conserve energy. Sympathetic center controls accelerating HR, increasing metabolism, thus increasing energy consumption

Nervous System Flow Chart

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

Nervous System Anatomy of a Neuron 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

Nervous System Dendrites Carry impulses from the environment or other neurons to the cell body

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

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

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

The Nerve Impulse The Resting Neuron 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)

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

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

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

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

Nerve Impulse Summary

Nerve Impulse Pathway Overview Impulse is received by the dendrites from the environment or another neuron, then gets rapidly channeled through the cell body to the axon 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). Vesicles release neurotransmitters into the open space between neurons called the synapse. Talk about speed of impulse. Dopamine and serotonin and ecstasy: similar to meth, X damaged cells that release the neurotransmitter called serotonin. Damage to these cells could affect a person's abilities to remember and to learn. Same for dopamine. Death of dopamine cells causes Parkinson's disease

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

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

Nervous System 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? Vision Hearing and Balance Smell and Taste Touch

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

Nervous System Accelerate HR, BP, and breathing rate Drugs and the Nervous System 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 Caffeine Cocaine Methamphetamines

Nervous System Depressants Slow down HR, lower BP and breathing rate, relax muscles and relieves anxiety Alcohol Marijuana Sleeping Pills

Commonly Abused Drugs Commonly Abused Drugs Section 35-5 Drug Type Stimulants Depressants Opiates Used to increase alertness, relieve fatigue Used to relieve anxiety, irritability, tension Used to relieve pain Medical Use Amphetamines Barbiturates Tranquilizers Morphine Codeine Examples Effects on the body 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