Nervous Tissue

1
Nervous Tissue

• Introduction
• The body has 2 major control centers
• One for rapid response (nervous system)
• One that makes slower but not less important
  adjustments for maintaining homeostasis
  (endocrine system)
• So, the body is controlled regulated by the
  nervous system the endocrine system.

2
Nervous system (NS)

• NS is a complex highly organized network of
  billions of neurons neuroglia.
• Neuron (nerve cells)-functional unit of the
  nervous system
• Neuroglia (glial cells)- supporting cells that
  protect and support the neurons

3
(No Transcript)
4
Neuron Classification

• a) sensory Neuron (afferent) The neurons that
  carry sensory information into brain spinal
  cord.
• exteroceptors external environment
• proprioceptors body position
• interoreceptors internal organs
• b) motor Neuron (efferent) carry motor
  information from CNS to other parts of body.
• c) interneurons or Internuncial (middle)
• Ganglion- large collection of neuron cell bodies

5
(No Transcript)
6
Nervous System consists of

• Brain cranial nerves
• Spinal cord spinal nerves
• Ganglia, enteric plexus sensory receptors

7
(No Transcript)
8
Function of the Nervous system

• Sensing various smells
• Producing speech
• Remembering
• Providing signals- control body movements
• Regulating the operation of internal organs

9
Function groups

• 3 basic functions of nervous system
• Sensory function sensory receptors detect
  internal stimuli (such as increase in blood
  acidity) external stimuli (such as a rain drop
  landing on your arm).
• Integrative function The nervous system
  integrates Sensory information by analyzing
  storing some of it making decisions for
  appropriate responses (interneurons).

10
Motor Function

• Based on the sensory input and integration, the
  nervous system responds by sending signals to
  muscles, causing them to contract, or to glands,
  causing them to produce secretions. Muscles and
  glands are called effectors because they cause an
  effect in response to directions from the nervous
  system. This is the motor output or motor
  function.

11
Organization of the Nervous System

• 2 major subdivisions
• Central nervous system (CNS)
• Brain spinal cord
• Peripheral Nervous system (PNS)
• Included all nervous tissue outside the CNS.

12
CNS (components)

• Brain is housed within the skull contains
  about 100 billions neurons. 12 pairs of cranial
  nerves (I- XII) are attached to the base of the
  brain.
• Spinal cord connects to the brain through the
  foramen magnum of the skull is enclosed by
  vertebral bony canal. It contains about 100
  millions neurons. 31 pairs of spinal nerves are
  attached to the spinal cord

13
(No Transcript)
14
PNS

• Cranial nerves their branches
• Spinal nerves their branches
• Ganglia sensory receptors

15
(No Transcript)
16
PNS (components)

• PNS may be subdivided into
• Somatic nervous system (SNS)
• Autonomic nervous system (ANS)
• Enteric nervous system (ENS)
• SNS consists of (1) - sensory neurons that
  convey information from somatic receptors in the
  head, body wall , limbs from receptors for
  the special senses to the CNS
• (2)- motor neurons- conduct impulses from CNS to
  skeletal muscle only (voluntary)

17
PNS (components)

• Autonomic nervous system (ANS) (1)sensory
  (2)motor information about visceral organs
  activities (involuntary)
• Enteric nervous system (ENS)- Intestine,
• enteric neurons govern contraction of GI tract
  (involuntary).