Nervous system Flashcards
The Nervous System is composed of:
Brain
Spinal Cord
Sensory receptors of sense organs
Nerves and Neuroglia
What are Nerves?
bundles of nerve fibers
What are Neuroglia?
tissues that support the nerve cells
Function of the Dendrite
branching extensions of a neuron that receive information and conduct impulses toward the soma.
What is the Soma?
the cell body of a neuron, which contains the nucleus.
Function of the Axon
the extension of a neuron through which neural impulses are sent.
Function of the Axon terminal
the endpoint of a neuron where neurotransmitters are stored. Form junctions with other cells.
Function of the Myelin Sheath
protects the axon and influences the speed of the neural impulses.
What is the Nucleus?
the “brain” of the cell.
What is the Nodes of Ranvier?
unmyelinated gaps between internodes. Axons may branch.
Neurons perform three basic functions, including:
Receiving information
Carrying the information
Passing the information on to the next neuron
What are Unipolar Neurons?
Cell body with a single process that divides into two branches and functions as an axon.
What are Bipolar Neurons?
Cell body with a process, arising from each end, one axon and one dendrite.
What are Multipolar Neurons?
Cell body with many processes, one of which is an axon, the rest dendrites.
What do interneurons do?
Transmits nerve impulses between neurons within the brain and spinal cord.
Connect sensory and motor neurons.
What do motor neurons do?
Conducts nerve impulses from the brain or spinal cord out to effectors– muscles or glands.
What do sensory neurons do?
Conducts nerve impulses from receptors in peripheral body parts into the brain or spinal cord.
Describe the 2 major efferent systems? motor neuron
Somatic: innervate skeletal muscles.
Visceral: innervate all other peripheral effectors (smooth muscle, cardiac muscle, glands, adipose tissue).
Describe the 2 major afferent systems? sensory neuron
Visceral: monitor internal environment
Somatic: monitor effects of external environment
What Neuroglial cells are found in the CNS?
Astrocytes
Oligodendrocytes
Microglia
Ependyma
What Neuroglial cells are found in the PNS?
Schwann Cells
Satellite Cells
List what is and function of Astrocytes?
Star-shaped cells that are located between neurons and blood vessels.
Functions:
Maintain blood-brain barrier.
Create three-dimensional framework for the central nervous system.
Repair damaged neural tissue.
Guide neuron development.
Control interstitial environment.
Communication with other nerve cells.
List what is and function of Oligodendrocytes
Shaped like astrocytes, but have fewer cellular processes.
Occur in rows along axons.
Functions:
Form myelin sheaths within the brain and spinal cord.
Produce nerve growth factors.
List what is and function of Microglial
Small cells with few cellular processes.
Migrate through neural tissue.
Functions:
Structural Support
Clean up cellular debris, waste products, and pathogens.
List what is and function of Ependyma
Cuboidal and columnar cells.
Found in the inner lining of brain ventricles and the central canal of the spinal cord.
Contain stem cells for repair.
Functions:
Secrete, circulate, and monitor cerebrospinal fluid (CSF).
List what is and function of Schwann Cells
Cells with abundant lipid-rich membranes that wrap tightly around the axons of peripheral neurons.
One cell per segment of axon.
Functions:
Speed neurotransmission
Vital for the development, maintenance, and regeneration of peripheral nerves.
List what is and function of Satellite Cells
Small, cuboidal cells that surround cell bodies of neurons in ganglia.
Functions:
Support ganglia in the PNS.
Help to regulate neuronal microenvironment.
Function for CNS?
PROCESS and COORDINATE
Sensory Data:
Inside and outside of the body.
Motor Commands
Activity of organs (e.g. skeletal muscles)
“Higher” Brain Function
Intelligence, memory, learning and emotion.
What makes up the peripheral NS?
Made up of nerves (peripheral nerves):
Bundles of axons (+ connective tissue and vessels)
Describe Somatic NS?
Voluntary and involuntary skeletal muscle contractions.
Describe ANS?
Subconscious actions (smooth and cardiac muscle, glands).
Effects of Parasympathetic NS?
“rest and digest”
Calms body and produces opposite effects of sympathetic.
Reduces heart rate and breathing.
Restores digestion.
Effects of Sympathetic NS?
“fight or flight”
Most active when afraid, angry, or aroused.
Increases heart rate and breathing.
Stops digestion.
What is the Enteric Nervous System?
This is also known as the “third division” of ANS.
Extensive network in digestive tract walls.
Complex visceral reflexes coordinated locally.
Roughly 100 million neurons.
What is the synapse?
The synapse is the area where a neuron communicates with another cell. Think of them like connectors, connecting cells to one another, being able to send and receive messages.
what is the Presynaptic cell?
Neuron that sends message.
what is the Postsynaptic cell:
Cell that receives the message.
What is the synaptic cleft
also sometimes called synaptic gap is the small gap that separates the presynaptic membrane and the postsynaptic membrane.
what is the synaptic terminal:
Contains synaptic vesicles of neurotransmitters
What are neurotransmitters?
Chemical messengers released in the synaptic cleft which affects the receptors of the postsynaptic membrane.
Describe the two different types of synapses
Neuromuscular Junction
Synapse between a neuron and a muscle.
Neuroglandular Junction
Synapse between a neuron and a gland.
Excitatory vs. Inhibitory Neurotransmitters
Excitatory neurotransmitters stimulate a neuron, increasing the likelihood of it firing an action potential and passing on a signal.
Inhibitory neurotransmitters suppress a neuron, decreasing the chance of it firing an action potential.
What does Alpha 1 do?
Releases intracellular calcium ions from reserves in the endoplasmic reticulum.
Has excitatory effect on target cell.
What does Alpha 2 do?
Lowers cAMP levels in the cytoplasm
Has inhibitory effect on the cell.
Helps coordinate sympathetic and parasympathetic activities.
what does beta do
Affect membranes in many organs (skeletal muscles, lungs, heart, and liver).
Trigger metabolic changes in target cell.
Function of B1, B2, and B3
Beta-1 (B1)
Increases metabolic activity.
Beta-2 (B2)
Triggers relaxation of smooth muscles along respiratory tract.
Beta-3 (B3)
Leads to lipolysis, the breakdown of triglycerides in adipocytes.
There are five main membrane processes in neural activities:
Resting Potential
The membrane potential of resting cell.
Graded Potential
Temporary, localized change in resting potential.
Caused by a stimulus.
Action Potential
Is an electrical impulse that is produced by graded potential.
Propagates along the surface of axon to synapse.
Synaptic Activity
Neurotransmitter is released.
Graded potentials in postsynaptic membrane.
Information Processing
Response (integration of stimuli) of postsynaptic cell.
