Exercise 21: Nervous System

• Nervous system - responsible for perception of stimuli, transmission of sensory signals or impulses to the CNS and the induction by the CNS for the action of muscles and glands
• In smaller organisms and less complex animals like the sponge, coordination of various functions is done in the cellular or organelle level
• Nerve net - found in radially symmetrical animals except echinoderms wherein the system consists of a network of nerve cells almost evenly spread across the body of the animal
• Ladder type - found in animals like flatworms where in nerve cords are organized in a ladderlike manner that runs along the longitudinal axis
• In the ladder type of nervous system, located in the head region are a pair of what?

  Ganglia
• Ganglia - functional clusters of neurons
• Ganglionic type - found in annelids and arthropods wherein there is a dorsal and anterior cerebral ganglion (brain)
• What extends posteriorly from the cerebral ganglion?

  Ventral nerve cords
• Each pair of ganglia in each segment is connected by what?

  Nerve strands
• Tubular Type - found in vertebrates and referred to as such because of the presence of internal spaces in the brain and spinal cord
• What are the spaces in the vertebrate brain called which continue as the central canal in the spinal cord?

  Ventricles
• Label the following in the Ganglionic Nervous system of the cockroach.

  A) Antennae

  B) Compound eye

  C) Cerebral ganglion

  D) Ganglia

  E) Nerve cords

  F) Nerve strands

  
• How is the tubular nervous system divided?

  Central, Peripheral
• The central nervous system includes what?

  Brain, spinal cord
• The peripheral nervous system includes what?

  Somatic nervous system, autonomic nervous system
• Peripheral nervous system - includes the motor and sensory nerves that emerge from the brain (cranial nerves) and spinal cord (spinal nerves) and that this allows the relay of sensory info and also of the signals for voluntary and involuntary movements
• The first three spinal nerves will fuse to form what?

  Brachial plexus
• What does the first spinal nerve innervate?

  Tongue, jaw, hyoid
• What does 2nd spinal nerve innervate?

  Forelimb
• What does the third spinal nerve innervate?

  Shoulder
• What do the 4th, 5th and 6th spinal nerves innervate?

  Muscles and skin of the body wall
• The 7th, 8th and 9th spinal nerves proceed posterior and fuse to form what?

  Sciatic plexus
• What does the 7th spinal nerve innervate?

  large intestine, bladder, oviducts
• What do the 8th and 9th spinal nerves innervate?

  Hindlimbs
• What does the 10th spinal nerve innervate?

  cloaca, bladder, oviducts
• Label the following in the tubular nervous system of the toad.

  A) 1st

  B) 2nd

  C) 3rd

  D) Brachial plexus

  E) 4th

  F) 5th

  G) 6th

  H) 7th

  I) 8th

  J) 9th

  K) Sciatic plexus

  L) Sciatic nerve

  M) 10th

  N) Brachial enlargement

  O) Lumbar enlargement

  P) Filum terminate

  
• Brain is closely covered by what membranes?

  Meninges
• What are the inner and outer parts of the meninges respectively?

  Inner: Pia mater Outer: Dura mater
• Ventricles - inner cavities of the brain and are continuous with the central canal of the spinal cord
• What do the ventricles and central canal of the spinal cord contain?

  Cerebrospinal fluid
• Within the olfactory bulb is the ventricle called what?

  Rhinocoele
• What ventricles are contained within the telencephalon?

  Lateral ventricles
• The lateral ventricles converge posteriorly into what?

  Foramen of Monro
• What is the cavity within the diencephalon?

  Third ventricle
• Pineal gland - On the dorsal side of the diencephalon
• In intact brains, the diencephalon is covered by a heavily-vascularized structure called what?

  anterior choroid plexus
• The anterior choroid plexus that consists of cerebrospinal fluid produce what kind of cells?

  Ependymal cells
• What ventricles are contained within the mesencephalon?

  Optic ventricles
• Optic chiasma - fairly wide point of convergence of the optic nerves found at the mid-ventral side
• Infundibulum - bi-lobed and is an extension of the diencephalon