weel 3 of physio bio

• The nervous system is divided into 2 major parts

  1.Central nervous system

  2. Peripheral nervous system
• Central nervous system


  Part of the nervous system that consists of the brain and spinal cord.
• Peripheral nervous system


  The part of the nervous system that is outside the central nervous system; it is made up of the somatic nervous system and the autonomic nervous system.
• Human brain consists of 3 different parts

  Brainstem

  Cerebrum

  Cerebellum
• Brainstem


  A stalk-like part of the brain consisting of medulla oblongata, the midbrain, and the pons, which joins the brain to the spinal cord.
• Cerebrum


  The largest portion of the brain, which is divided into two hemispheres.
• Somatic system contains two major types of neurons:


  Motor neurons

  Sensory neurons
• Motor neurons: Also called efferent neurons, motor neurons carry information from the brain and spinal cord to muscle fibers throughout the body.
• Sensory neurons: Also called afferent neurons, sensory neurons carry information from the nerves to the central nervous system.
• The autonomic system is the part of the peripheral nervous system that's responsible for regulating involuntary body functions, such as blood flow, heartbeat, digestion, and breathing.
• The autonomic system is further divided into two branches:

  Parasympathetic system

  Sympathetic system
• Parasympathetic system: This helps maintain normal body functions and conserve physical resources. Once a threat has passed, this system will slow the heart rate, slow breathing, reduce blood flow to muscles, and constrict the pupils. This allows us to return our bodies to a normal resting state.
• Sympathetic system: By regulating the flight-or-fight response, the sympathetic system prepares the body to expend energy to respond to environmental threats. When action is needed, the sympathetic system triggers a response by accelerating heart rate, increasing breathing

  rate, boosting blood flow to muscles, activating sweat secretion, and dilating the pupils.
• Neurons are the basic working unit of the brain, a specialized cell designed to transmit information to other nerve cells, muscle, or gland cells.
• Neurons are cells within the nervous system that transmit information to other nerve cells, muscle, or gland cells. Most neurons have a cell body, an axon, and dendrites.
• The cell body of a neuron contains all of the components that allow the cell to function (e.g. mitochondria and ribosomes). It also contains the nucleus. The cell body of a neuron is specialized for its particular functions.
• Axon is the output side of the neuron. Unlike the dendrites, there is usually only one axon emanating from each cell body. This single axon can also branch, but there are usually far fewer branches to the axon of a neuron than to its dendrites.
• Dendrites

  -Every neuron has an input and an output. These are the input side of the neuron. They often look like the branches of a tree in winter. They have specialized areas for receiving chemicals released by other neurons.
• Neurotransmitters

  • A chemical that is released by a neuron and travels across the synapse to bind to receptors on the postsynaptic terminal of another neuron to change the electrical activity of the target cell.
• Some Neurotransmitters 


  • Acetylcholine (ACh)
  • Dopamine
  • Serotonin
  • Norepinephrine
  • GABA (gamma-aminobutyric acid)
  • Glutamate
• Acetylcholine (ACh)


  Enables muscle action, learning, and memory
• Dopamine


  Influences movement, learning, attention, and emotion
• Serotonin


  Affects mood, hunger, sleep, and arousal
• Norepinephrine


  Helps control alertness and arousal
• GABA (gamma-aminobutyric acid)


  A major inhibitory neurotransmitter
• Glutamate


  A major excitatory neurotransmitter; involved in memory
• Examples of Malfunctions in Acetycholine (ACh) 


  With Alzheimer's disease, ACh-producing neurons deteriorate
• Examples of Malfunctions in Dopamine 


  Oversupply linked to schizophrenia. Undersupply link to tremors and decreased mobility in Parkinson's disease
• Examples of Malfunctions in Serotonin 


  Undersupply linked to depression. Some antidepressant drugs raise serotonin levels
• Examples of Malfunctions in Neropinephrine

  Undersupply can depress mood
• Examples of Malfunctions in GABA (gamma-aminobutyric acid) 


  Undersupply linked to seizures, tremors, and insomia
• Examples of Malfunctions in Glutamate 


  Oversupply can overstimulate the brain, producing migraines or seizure (which is why some people avoid MSG, monosodium glutamate, in food)
• Myelin sheath

  A white fatty material (enclosing the axons of some neurons) that insulates the neurons and permits the rapid transmission of electrical signals along the axon.
• Glia –An interconnected set of neurons that is needed for a functioning nervous system. also called glial cells or neuroglia, are non- neuronal cells in the central nervous system (brain and spinal cord) and the peripheral nervous system that do not produce electrical impulses. They maintain homeostasis, form myelin, and provide support and protection for neurons.
• Cerebellum is important for

  learning and coordinating complex movements.
• Cerebellum is the

  portion of the brain between the cerebrum and the brainstem.