Unit 2 Notes: Cells & Organization

Unit 2 Notes: Cells & Organization

(1) Neurons A neuron is a nerve cell. There are 2 types of neurons: Multipolar and Unipolar Every neuron has the same structural parts: Dendrites Receive incoming messages. Cell Body Integrate and process the incoming messages. Axon Send outgoing messages. Myelin Sheath Insulates the axon and increases the rate of nerve impulses. Axon Terminal Release neurotransmitters.

(2)Unipolar Neurons Unipolar neurons are used to transmit afferent/sensory input messages to the central nervous system. Unipolar neurons do not process incoming messages, therefore dendrites are not next to cell body. Using Unipolar Neurons: Dendrites receive stimulus from sensory organ. Message sent to cell body and out axon. Message sent to central nervous system.

(3) Multipolar Neurons Multipolar neurons are used to transmit efferent/motor output messages from the central nervous system. Multipolar neurons do process messages, therefore dendrites are next to cell body. Using Multipolar Neurons: Dendrites receive direction from central nervous system. Message sent to cell body and out axon. Message sent to effector organ to make it do something.

(4) Neuroglia Neuroglia function to support, insulate, and protect the neurons. Neuroglia cannot transmit nerve impulses. Types of Neuroglia: Astrocytes Microglia Ependymal Cells Oligodendrocytes Schwann Cells & Satellite Cells

(5) Astrocytes Connect neurons to capillaries. Transfer blood nutrients to neurons (and remove waste from neurons).

(6) microglia Phagocytize neuron debris and infectious agents.

(7) Ependymal Cells Pillow-shaped cells that line the brain and spinal cord cavities. Circulate cerebrospinal fluid. Provide shock absorption.

(8) Oligodendrocytes Flat, straw-shaped cells. Wrap around a neuron s axon. Provide fatty insulation for the axon, helping to form the myelin sheath.

(9) Schwann & Satellite Cells Schwann Cells: Form the myelin sheath with Oligodendrocytes. Satellite Cells: Provide protective cushioning around the cell body of neurons.

(10) Junctions A Junction is the meeting of a neuron and neuron, OR, a neuron and an organ. Also Known As Synapse or Synaptic Cleft Junctions are the location where neurotransmitters are released.

(11) Nervous System Organization Your nervous system is organized into different levels of communicative neurons. All stimuli messages going to the brain are transmitted through the Sensory / Afferent division. Outgoing Messages travel through either the: Autonomic or Somatic Division Sympathetic or Parasympathetic Division

(12) Defining the Levels Sensory = Afferent = Going toward the central nervous system. Motor = Efferent = Going away from the central nervous system. Somatic = Voluntary Autonomic = Involuntary Sympathetic = Emotional Parasympathetic = Non-Emotional

(13) Voluntary Responses 1. Stimulus 2. Message sent through sensory/afferent division to central nervous system. 3. Response 4. Message sent out motor/efferent division. 5. Out the somatic division. 6. To the effector organ.

(14) InVoluntary, Non-Emotional Responses 1. Stimulus 2. Message sent through sensory/afferent division to central nervous system. 3. Response 4. Message sent out motor/efferent division. 5. Out the autonomic division, and out the parasympathetic division. 6. To the effector organ.

(15) InVoluntary, Emotional Responses 1. Stimulus 2. Message sent through sensory/afferent division to central nervous system. 3. Response 4. Message sent out motor/efferent division. 5. Out the autonomic division, and the sympathetic division. 6. To the effector organ.