The Nervous and Endocrine Systems

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The Nervous and Endocrine Systems

• Chapters 41 and 42

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Functions of the Nervous System

• Uses chemical and electrical signals to send
  messages rapidly throughout the body.
• Receives and transmits information quickly.

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Neurons

• Specialized nerve cells that transmit information
  throughout the body.

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Parts of a Neuron

1. Dendrites- extend from the body of the neuron,
   act like antennae. Receive information from
   other cells. Carry impulses TOWARD the cell
   body.

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• 2. Axons extension of the cytoplasm that
  conduct nerve impulses, communicates with other
  cells. Carries impulses AWAY from the cell body.
  Nerves- bundles of axons.

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Parts of a Neuron

1. Myelin Sheath- layer of insulation on axons.
   Causes nerve impulses to move faster. Serves as
   protection.

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• 4. Nodes of Ranvier- gaps in the sheath, axon
  membrane is exposed.

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Communication between neurons

• SYNAPSE- where neurons meet other cells, tiny
  space between one cells axon and another cells
  dendrites. Nerve impulses move across- ONE way
  passage.

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• NEUROTRANSMITTERS chemical released at the
  synapse during a nerve impulse that sends a
  signal.

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Divisions of the nervous system

• CENTRAL PERIPHERAL
• brain and spinal cord
• SOMATIC AUTONOMIC
• relays info to and from relays information to
  internal
• skin and skeletal muscles organs
• SYMPATHETIC PARASYMPATHETIC
• controls organs during stress controls
  organs at rest

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The Central Nervous System

• Brain and spinal cord
• Acts as your bodys control center and
  coordinates all activities

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The Central Nervous System The Brain
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• Three types of neurons-
• 1. Sensory neurons send info from the sense
  organs TO the CNS.
• 2. Motor neurons send commands FROM the CNS to
  the muscles and other organs
• 3. Interneurons found in the brain and
  spinal cord.

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Types of Sensory Receptors
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The Central Nervous System The Brain

• Bodys main processing center.
• Consists of three major parts
• 1. Cerebrum
• 2. Cerebellum
• 3. Brain Stem

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The Central Nervous System The Brain, Cerebrum

• Largest part of the brain
• Responsible for learning, memory, perception and
  intellectual functions.
• Divided into two hemispheres (right brain and
  left brain)

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The Central Nervous System The Brain

• CEREBELLUM
• Located at the base of the brain
• Regulates balance, posture and movement
• Little brain

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• BRAIN STEM responsible for regulating vital
  functions breathing, sleep, heart rate,
  temperature
• 1.Midbrain
• 2. Pons
• 3. Medulla Oblongata

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The Central Nervous System The Brain

• Upper Brain stem contains relay centers that
  direct information to and from other parts of the
  brain
• 1. Thalamus sensory processing
• 2. Hypothalamus regulate vital functions,
  responsible for feelings of hunger and thirst,
  also regulates hormones.

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The Central Nervous System The Spinal Cord

• Links the brain to the PNS.
• Functions in reflexes sudden, involuntary
  contraction of muscles in response to a stimulus.
• Contains interneurons link neurons to each
  other.

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The Peripheral Nervous System (Questions 1112)

• Connects the brain and the spinal cord to the
  rest of the body.
• Has two divisions
• Sensory- controls the senses and sends message to
  CNS
• Motor- contains two different systems, the
  somatic and autonomic

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The Peripheral Nervous System Somatic Nervous
System

• Motor neurons that stimulate skeletal muscles.
• Most movements are voluntary and under your
  conscious control, except some reflexes.
• Reflexes do not involve the brain

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The Peripheral Nervous System Somatic Nervous
System

• Reflexes are an automatic UNCONSCIOUS response to
  a stimulus. Result of the shortest nerve
  pathway.
• Carried out without any assistance from the brain
  by the spinal cord.

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• After it happens the brain registers what
  occurred.
• Examples include sneezing, jerking away from
  something hot and your knee reflex.

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The Peripheral Nervous System Autonomic Nervous
System

• Not under conscious control.
• Carries info from the CNS to the internal organs.
• Regulates heart rate, blood flow and the muscles
  of the digestive, urinary, respiratory, and
  reproductive systems.

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• Has two divisions
• 1. Sympathetic
• 2. Parasympathetic

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The Autonomic Nervous System Sympathetic

• Maintains stability in the body
• Dominates in times of physical or emotional
  stress
• Fight or Flight response
• Increases blood pressure, heart rate and
  breathing rate

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The Autonomic Nervous System Parasympathetic

• Active under normal conditions
• Keeps your body functioning even when you are not
  active, especially during sleep.
• Turns off the fight or flight response

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The Endocrine System Hormones

• HORMONES substances released by cells that act
  to regulate the activity of other cells in the
  body. 4 main functions
• 1. Regulate growth, development, behavior and
  reproduction
• 2. Coordinate the production, use and storage
  of energy

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• 3. Maintain homeostasis
• 4. Respond to outside stimuli
• VERY SPECIFIC- only acts with certain cells.

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The Endocrine System Glands

• Organ whose primary function is to secrete
  materials to other regions of the body.
• ENDOCRINE gland - ductless organs that secrete
  hormones into the blood stream or fluid around
  cells.

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• EXOCRINE gland deliver hormones through ducts
  (tubes) to other parts of the body.
• Brain, stomach, small intestine, pancreas,
  kidney, liver, heart

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Nervous vs. Endocrine
NERVOUS ENDOCRINE
Chemical Messengers neurotransmitters hormones
Response time Fast-acting, shorter lived IMMEDIATE Slow-acting, longer lived
Point of release Neurotransmitters are released from nerve cells directly to adjacent nerve cells Hormones can be released into the blood stream or fluid around cells
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Major Endocrine Glands Hypothalamus

• Area of the brain that coordinates the activities
  of the nervous and endocrine systems.
• Controls temperature, blood pressure, and
  emotions.

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• Responds to signal received from the brain by
  issuing instructions-in the form of hormones- to
  the next big gland the pituitary gland

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Major Endocrine Glands The Pituitary Gland

• Endocrine gland suspended from the hypothalamus
• Known as the master gland because it controls
  the functioning of almost all the endocrine
  glands in the body.

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Comparing the nervous systems of invertebrates
and vertebrates.

• Mostly all animals except sponges have some form
  of nerve cells.