Central

Overview

¾ Nervous and endocrine systems major regulators of the body • Rapid response to external & internal stimuli

Nervous System = 2 systems • (CNS) • Peripheral Nervous System (PNS)

¾ CNS consists of: 1. 2.

¾ PNS consists of: 1. Afferent (sensory) division 2. Efferent (motor) division 9 Efferent system divided into (SNS) 9 Autonomic nervous system (ANS)

1 Central nervous Spinal Figure 5.1 Brain system cord Page 136 (CNS) (Input to CNS (Output from CNS from periphery) to periphery)

Peripheral Afferent nervous Efferent division system division (PNS)

Sensory Visceral Somatic Autonomic stimuli stimuli nervous system nervous system

Motor Sympathetic Parasympathetic nervous system nervous system

Skeletal Smooth muscle Cardiac muscle muscle Glands Effector organs (made up of muscle and gland tissue)

3 Classes of Neurons

1. Afferent neurons

2. Efferent neurons

3.

Central Peripheral nervous system nervous system (spinal cord)

Cell body terminals Afferent

Central Peripheral axon axon (afferent fiber) Receptor

Interneuron

Axon terminals Efferent neuron* Effector organ (muscle or gland) Cell Axon body (efferent fiber)

2 Central Nervous System

Cells of the CNS

¾ in CNS comprised of glial cells or neuroglia: 1. : scaffolding, blood-brain barrier, injury & scar tissue, remove excess K+, enhance chemical signaling 2. : form sheaths in CNS 3. : immune defense cells of CNS 4. Ependymal cells: support cerbrospinal fluid, possibly aid in formation of new neurons & glial cells

Space containing

Ependymal cell

Astrocyte

Microglial cell Figure 5.3 Page 138

3 Protection for the Brain 1. Bony structures –cranium

2. Cranial a. (outermost) b. arachnoid c. (innermost)

3. Cerebrospinal fluid & Ventricles • Cushioning, support, & nutrient transportation

4. Blood-brain barrier

Cerebrospinal fluid Figure 5.6 (1) Page 141

Pia mater Cranial meninges Dura mater

Pia mater Arachnoid mater Spinal meninges Dura mater

Figure 5.6 (2) Page 141

Scalp Skull bone Dura mater

Arachnoid mater

Pia mater

Brain ()

4 CSF and Ventricles ¾ Fluid filled cavities within the brain • Cerebrospinal fluid 9Shock absorption 9Higher in Na+ than K+

Right lateral ventricle

Left lateral ventricle

Third ventricle

Central canal of spinal cord Figure 5.5 Page 139 Fourth ventricle

5 Blood-brain Barrier ¾ Highly selective • Tight junctions

9H20 soluble compounds need active transport Pore passage Carrier-mediated transport Lipid-soluble substances

Transport Transport mechanisms mechanisms Lipid-soluble substances

Tight junction (no pores) Water-lined pore

Anatomical Organization of the Brain

Table 5.3 (1) Page 144 Cerebral cortex

Basal nuclei

Thalamus

Hypothalamus

Cerebellum Midbrain

Brain stem Pons Medulla

6 Major Functions

1. Cerebral Cortex (Cerebrum) • Sensory perception • Personality & language • Conscious & memory • Complex motor patterns (voluntary movement)

Cerebral Cortex Lobes

1. Frontal lobe – voluntary motor activity (primary ), speaking, thought

2. Parietal lobes – proprioception & body feelings (somatosensory cortex)

3. Temporal lobe – auditory/olfactory areas

4. – visual areas

Frontal lobe Parietal lobe

Occipital lobe

Temporal lobe

7 Primary motor cortex

Somato- sensory cortex

Major Functions 2. Basal nuclei (Cerebrum) • Inhibition of muscle tone • Suppress unwanted patterns of movement • Monitor and sustain slow contractions (i.e. posture)

Basal nuclei (gray matter)

Major Functions 3. Thalamus • Part of diencephalon • Relay station for synaptic (sensory) input 9 Screens out insignificant signals • Role in motor control

Thalamus

8 Major Functions

4. Hypothalamus • Homeostatic function • Temperature, thirst regulation (urine output), food intake • Link between nervous & endocrine systems 9 ANS coordinating center • Emotional & behavioral patterns

Mamillary bodies (part of hypothalamus)

Major Functions 5. Limbic System • Region surrounding brain stem in forebrain • Emotion & behavior patterns

Major Functions 6. (between brain stem & cerebrum) • Vestibulocerebellum 9 Balance & eye movement • Spinocerebellum 9 Coordinated skill & voluntary movements • Cerbrocerebellum 9 Planning & initiation of voluntary movement

Vestibulocerebellum Spinocerebellum Cerebrocerebellum

Cerebellum

9 Major Functions 7. (medulla, pons, midbrain) • Houses majority of • CV, Respiratory, & digestive control centers • Regulation of muscles involved in (equilibrium & posture) • Reception of synaptic input from spinal cord

Brainstem

Spinal Cord

Figure 5.28 Page 173

Cervical Cervical cord nerves Vertebrae

Thoracic Thoracic nerves cord

Lumbar Lumbar nerves cord

Sacral Sacral nerves cord Coccygeal nerve

10 Spinal cord Figure 5.27 Page 172 Dorsal root

Spinal nerve Meninges (protective Vertebra coverings)

Intervertebral disk

1. Gray Matter • Shaped like the letter H 9 Neurons & glial cells

2. • Myelinated nerves (ascending & descending tracts)

3. Ventral roots • Motor nerves

4. Dorsal roots • Sensory nerves • (groups of cell bodies)

Cell body of White matter Gray matter efferent neuron

Cell body of afferent neuron Dorsal root

Afferent fiber Dorsal root ganglion

From receptors

To effectors

Ventral root

Spinal nerve Figure 5.29 Page 174

11 Reflexes & the Spinal Cord

= Inhibitory interneuron Components of a Figure 5.33 = Excitatory interneuron arc Page 178 = = Inhibits Receptor = Stimulates Afferent pathway Integrating center Efferent pathway Effector organs Thermal pain receptor in finger Ascending pathway to brain Afferent Pathway

Stimulus

Biceps Efferent pathway (flexor) Integrating center contracts Triceps (spinal cord) (extensor) Hand relaxes withdrawn Effector organs Response

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