Human Systems Nervous System Integumentary System Skeletal System Muscular System Circulatory System
What is the function of the nervous system? To receive information from a sensory neuron To process info. by the brain & spinal cord To respond by an effectors (muscle/gland)
Neuron Nucleus Axon terminals Cell body Myelin sheath Dendrites Axon nodes
Structure of Neurons Cell body Nucleus Dendrites- carries impulses toward the cell body. Axon- carries impulses away from the body. Myelin sheath- covers part of some axons. Synapse: at the end of the axon
The Synapse The location at which a neuron can transfer an impulse to another cell.
Two connecting neurons: Axon ending Impulse direction Dendrite of new neuron Axon Cell Body
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The Central Nervous System: 1) Spinal Cord 2) Brain medulla for breathing cerebellum for balance cerebrum for higher thinking bw
Divisions of the Nervous System- The nervous system has two major divisions: central nervous system peripheral nervous system
b. processes information c. analyzes information The central nervous system- is made up of the brain and the spinal cord. Functions: a. sends messages b. processes information c. analyzes information
The brain- is the place to which impulses flow and from which impulses originate. The brain contains approximately 100 billion neurons
Regions of the Brain i. The cerebrum- controls voluntary actions. ii. The cerebellum- coordinates involuntary actions. iii. The brain stem- controls basic body functions. iv. The thalamus- receives impulses from the senses and sends them to the cerebrum. v. The hypothalamus- connects the nervous and endocrine systems.
The spinal cord- connects the brain with the rest of the body. Some reflexes are processed in the spinal cord. a. Reflex- is a quick automatic response to stimulus.
Cerebral Cortex= higher thinking
Parts of the Cerebrum
Cerebellum & “old brain” controls basic body functions
Right versus left Cerebrum
Infrared Tools to Study the brain . . . .
Multiple Sclerosis (MS) Autoimmune disease Myelin sheaths destroyed reduced to hardened lesions (scleroses) Blindness, muscle weakness, speech disturbance, urinary incontinence Treatment: interferons, glatiramer (hold off attacks)
Any blow to the head does brain damage Example of amnesia & processing skills
from the sensory neurons to the central nervous system. The peripheral nervous system- transmits impulses from sense organs to the central nervous system and back to muscles or glands. The sensory division- sends impulses from the sensory neurons to the central nervous system. The motor division- sends impulses from the central nervous system to muscles and glands. somatic- control voluntary actions. autonomic- regulates activity that are automatic.
The 2 types of nervous responses a. Voluntary or Somatic System that use the brain & spinal cord b. Involuntary or Autonomic System Sympathetic (Fight or Flight) Parasympathetic (Rest and Digest)
2c. Effectors that do actions are the Muscles = voluntary use the somatic system involuntary use autonomic system Glands = make hormone messengers
The involuntary system: Autonomic basic body functions & reflex arcs
The Autonomic Nervous System
Reflexes Rapid, predictable, involuntary responses to stimuli Somatic Reflexes: stimulate skeletal muscles Eg. jerking away hand from hot object Autonomic Reflexes: regulate smooth muscles, heart, glands Eg. salivation, digestion, blood pressure, sweating
Reflex Arc (neural pathway) Five elements: Receptor – reacts to stimulus Sensory neuron CNS integration center Motor neuron Effector organ – muscle or gland
Patellar (Knee-jerk) Reflex Reflex Activities Pupillary Reflex Patellar (Knee-jerk) Reflex Stretch reflex Tapping patellar ligament causes quadriceps to contract knee extends Help maintain muscle tone, posture, & balance Optic nerve brain stem muscles constrict pupil Useful for checking brain stem function and drug use
Flexor (withdrawal) reflex: painful stimulus withdrawal of threatened body part Pin prick Plantar reflex: draw object down sole of foot curling of toes Babinski’s sign: check to see if motor cortex or corticospinal tract is damaged
Reflex = Involuntary Reaction Voluntary Reactions More neurons and synapses are involved longer response times Reflex = Involuntary Reaction Voluntary Reaction