Nervous System Structure Flashcards
(42 cards)
Glial cells
Aka neuralgia
Cells that support neuronal function
Capable of cellular division and healing in traumatic injury
Often responsible for brain cancer
Form myelin, maintain homeostasis, support and protect neurons in CNS and PNS
Types of glial cells
Microglia Ependymal cells Satellite cells Astrocytes Oligodendrocytes Schwann cells
Microglia
CNS’s macrophages, arriving from white blood cells called monocytes
Phagocytose microbes and cellular debris
Ependymal cells
Epithelial cells that line the space containing the cerebrospinal fluid
Connected through tight junctions and form the blood-cerebrospinal fluid barrier
Use cilia to circulate cerebrospinal fluid
Satellite cells
Support the ganglia, which are groups of cell bodies in PNS
Serve support function, supply nutrients to surrounding cells, control micro environment. Similar role to Schwann cells of CNS
Astrocytes
Star-shaped neuralgia in CNS that give physical support to neurons and help maintain the mineral and nutrient balance in interstitial space
Oligodendrocytes
Have processes that wrap many times around axons in CNS to form myelin sheaths
Can extend its processes to wrap around up to 50 axons in CNS
Similar to Schwann cells in PNS
Schwann cells
Wrap entire cell bodies around axons as myelin sheaths for conduction
Myelinating and non-myelinating Schwann cells
Non-myelinating involved in maintenance of axons and crucial for neuronal survival
White matter
Areas of nervous system that are composed of myelinated axons of neurons
Grey matter
Bundles of cell bodies of neurons
Nodes of Ranvier
Gaps between myelinated areas on axons through which an action potential slightly slows as it passes
Saltatory conduction
Action potentials jump from one node of Ranvier to the next, appearing to jump over myelinated areas, while in reality are just moving very fast through myelinated areas
Myelin insulates the axons and reduces capacitance of membrane, allowing faster conduction
Three functions of neurons
- Sensory (afferent): receive signals from receptor cell that interacts with environments and transfers signal to other neurons, brain filters 99% of sensory information, located more dorsally
- Inter neurons: transfer signals from neuron to neuron, 90% of neurons in human body
- Motor (efferent): carry signals to muscle or gland (called effector), located more ventrally
Nerves
Bundles of neuron processes, this includes axons and dendrites
Known as tracts in CNS
Reflex
Quick response to a stimulus that occurs without direction from CNS
Can require or not require interneuron
Negative feedback loop: stretch reflex senses stretching and motor neuron responds in opposite way to stretch change and flexes the muscle to return to normal length
Information sent to CNS and reflexes can be modulated by CNS
Functions of CNS
Integrates nervous signals between sensory and motor neurons
Functions of PNS
Handles sensory and motor functions of nervous system
Divided into somatic nervous system and autonomic nervous system
Somatic nervous system
Part of PNS which serves to primarily respond to external stimuli
Sensory neuron cel bodies are located in dorsal root ganglion
Motor neurons inner gate skeletal muscle (voluntary movement) and cell bodies located in ventral horns of spinal cord, release acetylcholine to effectors
Autonomic Nervous System (ANS)
Coordinates involuntary response to environment, altering processes within body to produce most adaptive physiological state and behavior
Sensory: receives signals primarily from viscera (organs in ventral body cavity)
Motor: conducts signals to smooth muscle, cardiac muscle, and glands
* sympathetic
* parasympathetic
Sympathetic nervous system
“Fight or flight” responses
Increases heart rate and stroke volume
Constructs blood vessels around digestive and excretory organs
Signals originate in neurons whose cell bodies are in the spinal cord. Cell bodies of postganglionic neurons lie far from effectors (within paravertebral ganglion) for coordinated strong response
Parasympathetic nervous system
“Rest and Digest”
Decreases heart rate and increases digestive and excretory activity
Signals originate in neurons whose cell bodies are found in the spinal cord and brain. Cell bodies of postganglionic neurons lie inside or near their effectors
What neurotransmitters does the ANS use?
All preganglionic neurons in ANS use acetylcholine with nicotinic (cholinergic) receptors across the synapse
All postganglionic neurons in parasympathetic branch use acetylcholine and muscarinic receptors at the effectors (cholinergic)
Postganglionic neurons in sympathetic nervous system use norepinephrine or epinephrine (noradrenaline and adrenaline) with adrenergic receptors at the effectors
Spinal cord
Acts as a bridge between peripheral nervous system and brain, conveying sensory and motor signals
Possesses limited integration functions such as walking reflexes, leg stiffening, and limb withdrawal from pain
Lower brain
Earlier stage of evolutionary development
Brainstem, cerebellum, and diencephalon
Integrates unconscious activities such as respiratory system, arterial pressure, salivation, emotions, and reaction to pain and pleasure
