A&P 4 Flashcards
What are the two main divisions of the nervous system?
Central Nervous System
Peripheral Nervous System
What makes up the Central Nervous System?
Brain and Spinal Cord
What makes up the Peripheral Nervous System?
Cranial and spinal nerves
What are the functions of the CNS?
It is the integrative and control center
What are the functions of the PNS?
It is the communication line between the CNS and the rest of the body
What are the divisions of the PNS?
Sensory and Motor divisions
What are the divisions of the motor division?
Somatic and Autonomic nervous systems
What are the divisions of the autonomic nervous system?
Parasympathetic and sympathetic nervous systems
What makes up the sensory division of the PNS?
Somatic and visceral sensory nerve fibers
What is the function of the sensory division of the PNS?
It conducts impulses from receptors to the CNS
What makes up the motor division of the PNS?
Motor nerve fibers
What is the function of the motor division of the PNS?
It conducts impulses from the CNS to the effectors
What are the effectors of the PNS?
Muscles and glands
What is the function of the Autonomic nervous system?
It conducts impulses from the CNS to cardiac muscles, smooth muscles, and glands
What is the function of the somatic nervous system?
It conducts impulses from the CNS to skeletal muscles
What neurons make up the autonomic nervous system?
Involuntary; visceral motor neurons
What neurons make up the somatic nervous system?
Voluntary; somatic motor neurons
What is the function of the sympathetic division?
It mobilizes body systems during emergency situations; fight or flight system
What are the functions of the parasympathetic division?
It conserves energy and promotes nonemergency functions
What is the function of the nervous system in general?
It communicates and controls the various physiological functions of the body
What is the function of the sensory input?
It gathers info from both external and internal environments
What is the function of the integration and control center?
It receives input from the sensory neurons and determines the appropriate response
What is the function of the motor output neurons?
It initiates the response from the integration and/or control center
What receptors do somatic sensory neurons receive information from?
Proprioceptors
Chemoreceptors
Baroreceptors
What receptors send information through visceral sensory neurons?
Splanchinic/ gut
What receptors send information via special sensory neurons?
Ocular, auditory, etc
What receptors receive information from the somatic motor neurons?
Skeletal muscles receptors
What receptors receive information from the autonomic motor neurons?
Smooth muscle and glandular receptors
What type of receptors receive information from the parasympathetic and sympathetic nervous system?
Excitatory and inhibitory receptors
What receptors receive information from the enteric nervous system?
Gastrointestinal receptors
What are the three types of neurons that make up the afferent division of the PNS?
Somatic sensory
Visceral sensory
Special sensory
What are the two types of neurons that make up the efferent division of the PNS?
Somatic motor
Autonomic motor
What are the four neuroglia of the CNS?
Astrocytes
Microglia
Ependymal cells
Oligodendrocytes
What is the function of oligodendrocytes?
Cytoplasmic extensions become insulating myelin sheaths
What is the function of the ependymal cells in the CNS?
They cushion the brain and spinal tissue by circulating cerebrospinal fluid with their cilia
What is the function of the microglia in the CNS?
They are the ‘immune cells’ of the CNS; they sense neuronal health and degrade harmful substances
What are the functions of the astrocytes in the CNS?
~They provide anchoring supposrt for neurons and insure nutrient delivery
~They direct neuronal growth
~They take up potassium ions and used neurotransmitters (importance of glucose)
What are the two types of neuroglia of the PNS?
Satellite cells
Schwann cells
What are the functions of the satellite cells?
~They surround neuronal bodies
~They provide similar functions as the astrocyes in the CNS
What are the functions of the schwann cells in the PNS?
~They surround larger PNS fibers with myelin
~They help with peripheral nerve fiber regeneration
~They are similar in function to the oligodendrocytes in the CNS
What is the myelin sheath made of?
Fatty protein-lipids
What are the functions of the myelin sheath?
~They protect and insulate the axon
~They speed up the electrical transmissions (150 m/s vs 1 m/s for unmyelinated)
What makes up the neurolema?
The nucleus and cytoplasm of the schwann cell
What are the nodes of Ranvier?
They are the gaps in the myelin sheath
What are the two types of matter in the CNS and what do their names represent?
~White matter- named because their myelination makes it look white
~Gray matter- named because their unmyelinated axons look gray
What are three important facts we need to know about neurons?
~They can live over 100 years
~They are amiotic, meaning they cannot divide
~They have a high metabolic rate; thats why they require constant oxygen and glucose
What is the function of neurons?
They conduct nerve impulses
What are the three functional components of a neuron?
~Receptive region
~Conducting component
~Secretory component
What makes up the receptive region of the neuron?
Dendrites and cell body
What makes up the conducting component of a neuron?
The axon
What makes up the secretory component of a neuron?
The axon terminals
What type of neuron has many processes that extend from the cell body, but they’re all dendrites except for a single axon?
Multipolar neuron
What type of neuron has two processes that extend from the cell in shich one is a fused dendrite and the other is an axon?
Bipolar neuron
What type of neuron has one process that extends from the cell body and forms central and peripheral processes, which together comprise the axon (only the distal endings of the peripheral process are dendrites)?
Unipolar (pseudounipolar) neuron
What is the function of the receptive region or a neuron?
It receives impulses from a stimulus
What is the function of the conducting region of a neuron?
It generates/transmits an action potential
What is the function of the secretory region of a neuron?
It releases neurotransmitters
What is the relationship of the anatomy of the receptive region of a neuron?
The plasma membrane exhibits chemically gated ion channels
What is the relationship of anatomy of the conducting region of a neuron?
The plasma membrane exhibits voltage-gated Na+ and K+ channels
What is the relationship of anatomy of the secretory region of a neuron?
The plasma membrane exhibits voltage-gated Ca2+ channels
What are the somatic sensory neurons used for?
Afferent input from the body
What are the visceral sensory neurons used for?
Afferent input from the visceral organs
What are the visceral motor neurons used for?
Efferent output to the visceral organs
What are the somatic motor neurons used for?
Efferent output to the body
What is a nuclei?
The cell bodies within the CNS
What is a ganglia?
The cell bodies within the PNS
What are tracts?
Neuronal processes within the CNS
What are nerves?
Neuronal processes within the PNS
What is Ohm’s law?
Current (I) equals voltage (V) divided by resistance (R)
I = V/R
What is voltage in Ohm’s law?
potential
What is current in Ohm’s law?
flow of charge
What is resistance in Ohm’s law?
insulators and conductors
What is voltage of Ohm’s law in humans?
Ionic difference (membrane potential)
What is current of Ohm’s law in humans?
The flow of ions in and out of the cells
What is resistance of Ohm’s law in humans?
The plasma membrane
What are the types of ion channels of a cell membrane?
Leakage (non-gated)
Active (gated)
What are the two types of active (gated) ion channels are in plasma membranes?
Chemical and voltage
What defines electrochemical gradients?
~Movements of opposite charges
~Movement along a concentration gradient (high to low)
What is the most common resting membrane potential?
-70 mV
Is the outside or the inside of a cell more positive?
Outside
Is the outside or inside of a cell more negative?
Inside
At rest, what is the intercellular concentration of ions?
Higher K+ and lower Na+
At rest, what is the extracellular concentration of ions?
Higher Na+ and lower K+
What are the two mechanisms used to stabilize the resting membrane potential of a neuron?
~Permeability of plasma membrane (more positive outside than inside)
~Sodium potassium pump (actively stabilizes the membrane potential)
What is the name of ATP when it loses one phosphate group?
ADP- Adenosine Diphosphate
What is the name of ATP if it loses two phosphate groups?
AMP- Adenosine Monophosphate
What are the three components of ATP?
Adenine
Ribose
3 Phosphate groups
What does ATP stand for?
Adenosine Triphosphate
Describe the six steps used by the sodium-potassium pump to stabilize the membrane potential.
1-Cytoplasmic Na+ binds to the pump protein which stimulates phosphorylation by ATP
2-Phosphorylation causes the protein to change its shape
3-The shape change expels Na+ to the outside of the cell, and extracellular K+ binds to the protein
4-The binding of K+ triggers the release of the phosphate group
5-The loss of the phosphate restores the original conformation of the pump protein
6-The K+ is release and Na+ sites are ready to bind Na+ again; the cycle repeats
What happens during the depolarization phase of an action potential?
Na+ flows into the cell
What happens during the repolarization phase of an action potential?
Na+ channels start to close; K+ channels open and K+ flows out of the cell
What happens during the undershoot (hyperpolarization) phase of an action potential?
Na+ channels are closed, but K+ channels are sill open
What channels are being used while the membrane is at a resting state?
All gates are closed and only leakage occurs
What is the threshold potential?
It is the membrane potential that must be reached for an action potential to fire
What some important facts about action potentials that we need to know?
~Each action potential is identical to the one that triggered it
~Repolarization “chases” depolarization
~Local current flow depolarizes adjacent areas of the plasma membrane
~Action potentials follow the all or none phenomemnon
What is the absolute refractory period?
The perior when no other stimulus will generate an action potential (Na+ channels are still open)
What is the relative refractory period?
The period that follows the absolute refractory period when the neuron can receive another stimulus given the stimulus is strong enough
Why is stimulus strength important?
Stimulus strength alters nerve firing frequency assisting the CNS in determining a response
What is the function of the presynaptic neuron?
Sends impulse (or neurotransmitter) to the synaptic cleft
What is the function of the postsynaptic neuron?
Receives impulse (or neurotransmitter) from the synaptic cleft
What is an axodendritic synapse?
Where an axon clasps to a dendrite
What is an axosomatic synapse?
Where an axon clasps to a soma
*Not understood well
What is as axoaxonic synapse?
Where an axon clasps onto another axon
What are the steps of releasing a neurotransmitter?
~Ca2+ gates in the presynaptic terminal pull Ca2+ into axon
~Ca2+ triggers exocytosis (release of the neurotransmitter)
~The neurotransmitter tries to bond to the postsynaptic membrane
~Ion channels of the postsynaptic membrane open if the neurotransmitter binds to them
What excites a generator potential?
Energy (heat, light, etc..)
What does IPSP stand for?
Inhibitory postsynaptic potential
What does EPSP stand for?
Excitatory postsynaptic potential
When does IPSP occur?
During hyperpolarization
What does hyperpolarization do the the membrane potential?
Pushes the membrane potential away from the threshold potential
What does depolarization do to the membrane potential?
It pushes the membrane potential towards the threshold potential
What does the binding of a nerotransmitter lead to?
The opening of ion channels which will lead to a local change in membrane potential
Define subthreshold potential.
The timing between two stimuli was not close enough to have a summation effect
Define temporal summation.
When there is multiple stimuli in one place; one neuron transmits a stimuli over and over
Define spatial summation.
When more than one neuron is acting on anther; two or more axons are attached to the same neuron
What is important to note about IPSP, EPSP, and the summation affect?
One IPSP will ‘cancel out’ one EPSP of the same magnitude
Know table 11.2 (slide 29)
Know table 11.2 (slide 29)
What does is the acronym used for cyclic adenosine monophosphate?
cAMP
Describe the process of an indirect neurotransmitter.
~a neurotransmitter (ligand) is released into the synaptic cleft; a G protein complex attaches to a receptor in the plasma membrane
~The neurotransmitter (ligand) binds to the receptor causing GTP to be broken down to GDP
~The G protein is released from the receptor and activates the adenylate cyclase
~ATP is broken down into cAMP and two phosphates
~The release of cAMP causes an enzyme activation that changes membrane permeability and potential; There is an activation of specific genes that begin protein synthesis
What neurotransmitter is released by the somatic nervous system?
Acetylcholine
What is the effector organs of the somatic nervous system?
Skeletal muscles
What neurotransmitters are used (and where) by the sympathetic division of the autonomic nervous system?
~Acetylcholine is release at the ganglion and adrenal medulla
~Norepinephrine is released at the effector organ
~Both epinephrine and norepinephrine are released by the adrenal medulla into the blood vessels
What is the neurotransmitter used (and where) by the parasympathetic division of the autonomic nervous system?
Acetylcholine is released at both the ganglion and the effector organs
What are the effector organs of the autonomic nervous system?
Cardiac muscles, glands, and smooth muscle
When are Na+ channels inactive?
During the absolute refractory period
When are Na+ channels closed?
When repolarization need to happen
Where does the action potential start and where does it go?
The AP starts at the axon hillock and moves down the axon to the axon terminals
Why can norepinephrine and acetylcholine be both excitatory and inhibitory?
There are 2 different types of receptors for these neurotransmitters; the type of receptor on the postsynaptic membrane will determine whether these are excitatory or inhibitory
