Chapter 11- Nervous System Flashcards
2 major control systems to maintain homeostasis
Nervous system- works faster but effects are short lived. AP via neurons.
Endocrine system- takes longer to respond but effects last longer. Works by sending hormones through blood stream to target organs
Homeostatic regulation by the nervous system is dependent on
The systems ability to detect, interpret, and respond to changes
Functions of nervous system
-receiving sensory input. Monitor external and internal stimuli
-integrating information. Brain and spinal cord receive and initiate response.
-controlling muscles and glands
-maintain homeostasis
-establish and maintain mental activity. Consciousness, thinning, memory, emotion
Major divisions of nervous system
Central - brain and spinal cord receive (integration function)
Peripheral - all nerves leading and coming into CNS.
Division of peripheral nervous system
Afferent (sensory) - brings info into CNS
Efferent (motor) - takes info out to body organs
efferent division of peripheral nervous system
-somatic - from CNS to skeletal muscle. Voluntary. Single neuron system - one from spinal cord to muscle
-autonomic - from CNS to smooth, cardiac, and glands. Involuntary to maintain homeostasis.
Di
Difference in neuron systems bc somatic and autonomic
Somatic is a single neuron system with no gaps or ganglion. Neuron goes straight to the muscle.
Autonomic involves two ganglion neurons that connect CNS to organ. Allows for more regulation and modulation of autonomic responses.
Divisions of autonomic nervous system
Sympathetic - fight or flight
Parasympathetic - rest and digest
Enteric - (less discussed) consist of plexuses that are responsible for controlling digestive tract
Difference in function between CNS and PNS
CNS is for processing strimuli and initiating response
PNS detects stimuli (sensory receptors) and transmits info two and from the CNS.
The bear and the man scenario with the nervous system
- Afferent Sensory receptors in PNS detect bear and send info to CNS
- CNS processe and integrates the info to determine appropriate response
- PNS then uses efferent pathways to send info via the somatic system (to get skeletal muscle to run) and the autonomic system (to pump heart, prep organs for running, pump adrenaline)
Sensory receptors
Ending of neurons or seperate cells that detect such things as temperature, pain, touch, pressure, light, sound, odor
Nerve
A bundle of axons and their sheaths that connect connects CNS to sensory receptors, muscles, and glands.
12 pair cranial. 31 pair spinal.
Neuroglia
Cells that support and protect neurons. DO NOT transmit APs. More numerous than neurons in nerve tissue.
Neurons
Individual nerve cells that receive stimuli and transmit APs
Basic neuron structure
Cell body or soma
Dendrites
Axon
Neurons lack centrioles and are therefore unable to undergo mitosis
Dendrites of neuron
input part of neuron. cytoplasmic exfensions where axons of other neurons can form a synapse. Impulses sent to soma
Cell body or soma of a neuron
- contains rough ER broken into Nissl bodies. Primary site of protein synthesis for neuron.
Axon
Send AP away from soma
Axon hillock (cone structure btwn soma and axon) is where the threshold must be reached to AP in the axon
End of axon branches out to presynaptic terminals which are at the synapse to another neuron, muscle cell or gland
Terminals hold synaptic vesicles that contain neurotransmitter
May branch to form collateral axons which increase the # of APs
Axolemma
Cell membrane of an axon that can carry an AP
Interneuron
Within CNS from one neuron to another
Structural classification of neuron
Multipolar - one axon and many dendrites - most neurons in CNs
Bipolar- one axon one dendrite - sensory in special senses
Unipolar - cell body and axon with two branches extending to CNS and peripheral with sensory receptors. Most sensory neurons are unipolar.
Neuroglia of the CNS types
Astrocytes
Ependymal cells
Microglia
Oligodendrocytes
Astrocytes
Star shaped cells that wrap around and cover blood vessels. Making up the blood brain barrier to keep brain chemistry constant. (Keeps toxic substances out but allows diffusion to regular CSF)