AAP Nervous System Flashcards
What is the nervous system?
- consists of the brain, spinal cord, sensory organs, and all of the nerves that connect these organs with the rest of the body. These organs are responsible for the control of the body and communication among its parts
What are the functions of the nervous system?
- NS conducts sensory information to the central nervous system (brain and spinal cord) by sensory pathway (sensory nerves)
- Processing and interpretation of data from the sensory pathway by the brain
- Initiate response of effector (e.g. muscle contraction) by sending signals via the motor pathway (motor nerves)
What does the central nervous system consist of?
- brain
- spinal cord
What does the peripheral nervous system consist of?
- cranial nerves (12 pairs in both human and dog)
- spinal nerves (31 pairs in human & 36 pairs in dogs)
- PNS provides communication between CNS and the body
What is the function of the central nervous system?
- acts as the body’s control center
- coordinates the body’s activities –> nerve impulses travel through the neurons in your body to reach the brain
- all information must be sent to the CNS for integration and decision making
What is the function of the PNS?
- made up of all the nerves that carry messages to and from the CNS
- similar to telephone wires
- CNS and PNS work together to make rapid changes in your body in response to stimuli
- peripheral nervous system
What are the 2 major divisions of PNS?
- sensory (afferent) division
- motor (efferent) division
What does the sensory (afferent) division do?
- nerves carrying information to the CNS
- somatic(skin, muscle, joints) sensory nerves carry sensory inputs from skin, muscle, joints, are involved in the voluntary control of body movements
- visceral sensory nerves carry sensory impulses (usually pain or distention) from the internal organs, glands and blood vessels to the central nervous system
What does the motor (efferent) division do?
- nerves carrying information from the CNS
- Somatic nervous system –> voluntary; conducts impulses from CNS to skeletal muscles
- Autonomic Nervous System (ANS) –> involuntary; conducts impulses from CNS to cardiac muscles, smooth muscles, and glands; two divisions: sympathetic NS & parasympathetic NS
What are the divisions of the ANS?
- sympathetic nervous system
- parasympathetic nervous system
What does the sympathetic nervous system do?
- controls body in times of stress, such as the secretion of adrenal
What does the parasympathetic nervous system do?
- controls the body in times of rest, such as sleep
Structure of sympathetic NS and parasympathetic NS
- Sympathetic NS: nerves emerge from thoracic and lumbar regions
- parasympathetic NS: nerves emerge from the brain and the sacral vertebral regions (cranial-sacral)
- Sym and parasym NS usually have opposite effects on the same organ to balance the activity of the organ
What are the types of cells in the nervous system?
- neurons (nerve cells)
- glia (glial cells)
What do glia (glial cells) do?
- support, nourish and protect neurons like “glue”
What are neurons composed of?
- cell body (soma)
- processes
What are clusters of neurons known as?
- clusters of cell bodies in CNS are called nucleus (nuclei)
- clusters of cell bodies in PNS are called ganglia
What are processes?
- bundle of processes are known as nerves
- Dendrites: with large surface area to receive, conduct and signals to the cell body
- Axons: single, long process in each neuron, conduct and signals away from the cell body to other neurons
What forms the myelin sheath?
- some glial cells wrap tightly around the axon to form a sheath –> myeline sheath
- oligodendrocytes in CNS and Schwann cells in PNS
What is the neural circuit?
- in the brain, the neuronal population form very completed, interconnected network known as the neural circuit for highly efficient information exchange
- an estimated 100 billion neurons in humans and 500 million in dogs
What are the glial cells that form myelin sheaths?
- Schwann cells
- oligodendrocytes
What are the nodes of Ranvier?
- gaps between adjacent glial cells
- multiple glial cells cover the entire length of the axon
What is the purpose of the myelin sheath?
- an insulating layer which helps to conduct signals through the axon at a much faster speed than unmyelinated axons
What does gray matter consist of?
- unmyelinated axon terminals
- dendrites
- cell bodies
What does white matter consist of and what is its function?
- myelinated axons
- formation of nerves and/or tracts
