Chapter 12 Nervous tissue

Question 1

Overview of the Nervous System
(what does it control?)

Answer 1

• The nervous system (along with the endocrine system) helps to keep internal conditions within limits to maintain homeostasis and health.
  *The nervous system is responsible for all our behaviors, memories, and movements.
  *The branch of medical science that deals with the normal
  functioning and disorders of the nervous system is called
  neurology

Question 2

Nervous System Divisions

Answer 2

*Central Nervous System (CNS)
-consists of the brain and spinal cord
*Peripheral Nervous System (PNS)
-consists of cranial and spina nerves which contain both sensory and motor neurons
-connects CNS to effectors: muscles and glands (via motor pathways) and receptors (via sensory pathways)

Question 3

Subdivisions of the PNS

Answer 3

• Somatic (voluntary) Nervous System (SNS)
• sensory neurons from cutaneous receptors to the CNS
• motor neurons to skeletal muscle tissue
• Autonomic (involuntary) Nervous System (ANS)
• sensory neurons from viscera to CNS
• motor neurons to smooth & cardiac muscle and glands;
  Examples:
• sympathetic division (speeds up heart rate; inhibits digestion; both effects are
  consistent with the fight or flight response)
• parasympathetic division (slow down heart rate; promotes digestion)

Question 4

Overview of Major Structures
(Ganglia)

Answer 4

• 12 pairs of cranial nerves emerge from the brain
• 31 pairs of spinal nerves emerge from the spine
• Ganglia-located outside the brain and spinal cord, are small masses of nervous tissue, containing primarily cell bodies of neurons
• Enteric plexuses help regulate the digestive system

Question 5

Overview of Major Structures (Receptors & Effectors)

Answer 5

• Receptors are peripheral ends of sensory neurons in the form of bare nerve endings (such as those for pain), or more elaborate ends of sensory
  neurons (such as those that house endings for touch and pressure). Receptors monitor changes – stimuli –
  in the internal or external environment.
• Effectors respond to motor impulses and consist of muscles and glands.

Question 6

Functions of the Nervous System

Answer 6

• Sensory (afferent) neurons sense stimuli in the internal and external environment through receptors. They channel impulses to the CNS.
• Integrative function within the CNS: to analyze the sensory information, store some aspects, and make decisions regarding
  appropriate behaviors. Association neurons serve this function.
• Motor (efferent) neurons channel impulses from the CNS. They respond indirectly to stimuli channeled through the CNS by initiating action via muscle contraction or glandular secretion.

Question 7

Histology of Neurons
(Neurons & Cell Body)

Answer 7

• Neurons- are nerve cells, the functional units of the nervous system
  -neurons have the capacity to produce action potentials, aka nerve impulses. Electrical excitability is a key property
• Cell Body
  -single nucleus with prominent nucleolus
  -Nissl bodies (aka chromatophilic substance)
  –rough ER & free ribosomes for protein synthesis
• cell processes are the dendrites and axons