Life Science   Chapter 21   The Nervous System
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Life Science Chapter 21 The Nervous System

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Life Science   Chapter 21   The Nervous System Life Science Chapter 21 The Nervous System Presentation Transcript

  • The Nervous System
    • Neuron – working unit of the nervous system
    • Axon – carries messages away from the cell body
    • dendrites – receive the messages and send them to the cell body
    • Terminal Bud – send messages to other neurons
  • 3 types of neurons
    • Sensory neurons – send info to the spinal cord or brain
    • Interneurons – send info out of brain and spinal cords to the motor neurons
    • Motor neurons – send info from brain and spinal cord to muscles or glands
  • Sensory neuron (hand) Motor neuron (arm) Interneuron
  • Synapse
    • Small space in between neurons
    • Neurotransmitters are released in the synapse and starts an impulse in the next neuron
  • Synapse
  • Divisions of the Nervous System
    • CNS – central nervous system – brain and spinal cord
    • PNS – peripheral nervous system – all the nerves outside the CNS
  • Central Nervous System
    • Brain 100 billion neurons
    • 3 major parts
  • 1. Cerebrum
    • Divided into hemispheres
    • Memory is stored
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  • Cerebrum
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  • 2. Cerebellum
    • Under the cerebrum
    • Coordinated voluntary muscle movements
  • 3. Brainstem
    • Connects the brain to the spinal cord
    • Made up of the
      • Mid brain
      • Pons
      • Medulla
    • Controls homeostasis of heart, breathing, blood pressure, involuntary muscle movements
  • Peripheral Nervous System
    • 2 divisions of the peripheral nervous system
  • Peripheral Nervous System Somatic Nervous System Skeletal Muscle Autonomic Nervous System Heartrate, breathing, digestion, salivary glands
  • Reflex
    • Involuntary response to a stimulus
    • Involves a pathway called a ( reflex arc ) over which impulses travel
  • Reflex arc
    • Impulse is sent to the spinal cord
    • Impulse passes to an interneuron in the spinal cord which immediately relays the impulse to motor neurons
    • Motor neurons transmit the impulse to muscles in your arm
    • Your arm pulls back (Without thinking!)
  • Steps of a reflex arc
    • Receptor
    • Sensory neuron
    • Interneuron (spinal cord)
    • Motor neuron
    • Effector – “response”
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  • Your Endocrine System
  • Endocrine system
    • System of glands that release their products into the blood stream and broadcast messages throughout the body
  • Hormones
    • Affect specific tissues called target cells
    • Target cells – control activities in parts of the body other than right around the gland
  • Glands of the Endocrine System
  • Hypothalamus
    • Part of the brain
    • Produces hormones that influence the pituitary gland
  •  
  • Pituitary Gland
    • “ Master Gland”
    • Secretes numerous hormones
    • Growth-stimulating Hormone
    • Hormones to control specific glands
    • Thyroid Stimulating Hormone (TSH)
      • Tells thyroid to produce thyroxine
    • The Follicle Stimulating Hormone
      • Stimulates activity in the ovary and testes
  •  
  • Thyroid Gland
    • Located in the neck
    • Makes thyroxine
    • Regulates metabolism
  •  
  • Parathyroid Glands
    • Embedded in the thyroid gland
    • Secrete parathormone
    • Controls the metabolism of calcium
    • Necessary for nerve function, blood clotting, and proper growth of teeth and bones
  •  
  • Adrenal Glands
    • Two glands located on top of the kidneys
    • Each gland has 2 distinct regions
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  • Adrenal Cortex
    • Secretes two types of steroid hormones
    • promotes the conversion of body fat and protein into glucose
    • promotes the reabsorbtion into the blood stream of sodium and chloride ions by the kidney tubules
      • This affects the water balance and maintains BP
  • Adrenal Medulla
    • Secretes adrenalin in times of emergency
    • Increases the blood sugar level
    • Speeds heart and breathing rates
  •  
  • Islets of Langerhans
    • Located in the pancreas
    • Secrete insulin and glucagon
  •  
  • Insulin
    • Helps take glucose into cells
    • Lowers blood sugar levels by taking it out of the blood and storing it in the liver and muscle cells
  • Glucagon
    • Stimulates the release of sugar from the liver
    • Raises blood sugar level
  • Gonads
    • Sex glands
    • Testes
    • Secrete testosterone – develop male secondary sex characteristics
    • Ovaries
    • Secrete estrogen - develop female secondary sex characteristics
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  • Endocrine Control
    • Negative feedback system
    • Controls the amount of hormone an endocrine gland produces
    • Works like a thermostat in your house
  • Negative feedback system
    • Start: 1. Hormone level low
    • 2. Hormone production increases
    • 3. Hormone level high
    • 4. Hormone production slowed down
    • End: 5. Hormone level low
  • Endocrine Feedback System of TSH Hypothalamus Pituitary Gland Thyroid Stimulating Hormone Thyroid Gland Thyroxin stimulates Inhibits
  • Endocrine System Disorders
  • Goiter
    • Enlargement of the thyroid gland
    • Results in not being able to make thyroxine
    • Often associated with iodine deficiency in the diet
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  • Diabetes
    • Insulin deficiency
    • Results in an elevated blood sugar level
    • Also an inability of the body to store the sugar glycogen in the liver
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