CH 11 Flashcards
5 functions of the nervous system:
Sensory input Integration Control of muscles/glands Homeostasis Center for mental activities
Sensory Input
Sensory receptors monitor external and internal stimuli
Integration
the brain and spinal cord process and respond to sensory input
Homeostasis regulates…
other systems to maintain a constant internal environment
Control of muscles and glands
- Skeletal m. contract when stimulated by NS
- Smooth m., cardiac m., and glands are also under nervous control
center for mental activities
the brain is the center of mental activities including memory, emotions, thinking, and consciousness
Central nervous system (CNS)
- composed of the brain and spinal cord
- processes, integrates, stores, and responds to information from the PNS
Peripheral Nervous System (PNS)
- Nervous tissue external to the CNS
- Composed of sensory receptors and nerves
- detects stimuli and transmits information to the CNS and receives information from the CNS
PNS: Sensory Receptors
Ends of neurons or separate, specialized cells that detect: temperature, pain, touch, pressure, light, sound, odors
PNS: Nerve
-Bundle of axons and sheaths that connect CNS to sensory receptors, muscles, and glands
PNS: How many cranial nerves and where do they originate?
12; the brain
PNS: How many spinal nerves and where do they originate?
31; the spinal cord
PNS: Ganglion (singular)
collection neuron cell body located external to the CNS
PNS: Plexus
Extensive network of axons, and sometimes neuron cell bodies, located outside of the CNS
PNS: Sensory Division
- Afferent
- Transmits action potentials from receptors to CNS
PNS: Motor Division
- Efferent
- Transmits action potentials from CNS to effectors
PNS: motor division
- transmits APs from the CNS to effector organs
- composed of 2 subdivisions: somatic nervous system and autonomic nervous system (ANS)
Somatic nervous system
innervates skeletal m.
Autonomic nervous system (ANS)
Innervates cardiac m.
Subdivisions of the ANS:
Sympathetic, parasympathetic, enteric
what does to innervate mean?
to form a synapse with and transmit a AP
PNS: Autonomic Division
- Unconscious control
- Two neuron system
- sympathetic division
- parasympathetic division
- enteric division
PNS: Autonomic Division: Two Neuron System
- ) From CNS to ganglion
2. ) From ganglion to effector
PNS: Autonomic Division: Sympathetic Division
- Always active at basal levels but is most active during states of heightened stress
- Responsible for the fight or flight response
PNS: Autonomic Division: Parasympathetic Division
- bring internal variables down
- regulates resting functions
- slows the body down
PNS: Autonomic Division: Enteric Division
- controls digestive activities
- housed within the digestive tract
Will the sympathetic and parasympathetic divisions be activated at the same time?
no, they have a push/pull type of relationship
CNS consists of…and corresponds with…
brain and spinal cord…PNS
PNS consists of…and corresponds with…
-Nervous tissue outside the CNS
-Sensory receptors and nerves
…
2 way comms with CNs, talks to motor division, receives input from sensory division
Motor Division consists of…and corresponds with…
-carries APs away from CNS in cranial nerves or spinal nerves….. talks to ANS and somatic nervous system
the sensory division consists of…and corresponds with…
-transmits APs away from sensory receptors to the CNs….
only talks to PNS
Somatic Nervous system consists of…and corresponds with…
-innervates skeletal m.
ANS consists of…and corresponds with…
innervates cardiac m., smooth m, and glands… talks to sympathetic div., parasympathetic div, and enteric nervous system
the sympathetic division consists of…and corresponds with…
- most active during physical activity
- fight or flight
the parasympathetic division consists of…and corresponds with…
- regulates resting functions
- calm/at rest
the enteric nervous system consists of…and corresponds with…
controls the digestive system
Neurons
excitable cells that receive stimuli and transmit APs to other neurons or effector organs
What are neurons composed of?
- cell body (soma)
- dendrites
- axons
Dendrites
receive incoming information
axons
send outgoing information
Neuroglia (glial cells)
- non-neural cells
- cells that surround and support the functions of neurons
- account for over half of the brain’s weight
Neuron: Cell body (soma)
- contains the nucleus, nucleolus, and nissl substance
- mitochondria, golgi apparatus and other organelles are present
Neuron: Dendrites
Short, branched cytoplasmic extensions of the cell body
-conduct electric signals toward the cell body
Neuron: Axon
- cytoplasmic extension of the cell body
- transmit APs to other cells
Nissl substance
- an aggregate of rough ER and free ribosome
- primary site of protein synthesis in the neutron
what are clusters of cell bodies in the CNS called?
nuclei
what are clusters of cell bodies in the PNS called?
ganglia
Neuron Structure: Axon
- Trigger zone
- Most neurons have one un-branched axon (most branches, if present, are called collateral axons)
- presynaptic terminal
Trigger Zone
- Part of the neuron where the axon originates
- APs are generated here
Presynaptic Terminal
- branched terminus of an axon (10,000 or more)
- form synapses
- contain vesicles with neurotransmitters
What are the 3 categories that neurons are classified into according to the direction in which APs are conducted:
- sensory (afferent) neurons
- motor (efferent) neurons
- interneurons (association)
sensory (afferent) neurons
conduct APs towards the CNS