study of structure and the physical relationships between body parts
anatomy
example of anatomy
how a muscle attaches to the skeleton
study of living organisms perform vital functions
physiology
example of physiology
how a muscle contracts and the force it exerts
there is a close link between
structure and function
(blanks) at each level determines structure and function of higher levels
organization
organization of the human body
cellular–> tissue –> organ –> organ system–> organism
molecular interactions–> cell
cellular
example of cellular level
protein filaments
group of cells–> specific function
tissue
example of tissue level
coordinated contractions
> or equal to 2 tissues–> specific function
organ and organ system
example of organ
pump blood
example of organ system level
circulate blood through vessels
for life to continue, precise internal body conditions must be (BLANK)
maintained regardless of external conditions
homeostasis
existence of a relatively stable internal environment
the principal function of regulatory systems is to maintain
homeostasis
characteristics of homeostasis
- not a static process (dynamic equilibrium)
- requires energy
- conditions maintained via feedback systems
autoregulation (intrinsic regulation)
cell/tissue/organ adjusts to change in environment
extrinsic regulation
nervous system or endocrine system (adjust many simultaneously)
nervous system regulation characteristics
fast; short duration
nervous system
electrical communication via nerve tissue
endocrine system regulation characteristics
slow; long duration
endocrine system
chemical communication via bloodstream
homeostatic regulatory mechanisms require 3 parts
1) receptor
2) control center
3) effector
receptor
sensor sensitive to stimulus
control center
receives information from receptor and sends out commands
effector
responds to commands from control center
negative feedback
drives system toward set point
can a set point change?
yes
positive feedback
drives system away from set point
individual variability in set points
genetic factors, age, gender, general health, environment
3 types of membrane transport
1) diffusion
2) carrier mediated transport
3) vesicular transport
diffusion
passive, movement from high [solute] to low [solute] concentration gradient
what types of molecules for diffusion?
lipid soluble or small molecules
dissolved gases, lipid-soluble drugs, water through membrane
simple diffusion
water, ions through channel protein
channel mediated diffusion
special case of diffusion
osmosis
osmosis
diffusion of water across a selectively permeable membrane
water moves from (blank) to (blank) for osmosis
high [water] to low [water]
force with which water moves into that solution as a result of its solute concentration
osmotic pressure
what does hydrostatic pressure oppose
osmotic pressure
hypotonic looks like
cell full
hypertonic looks like
cell shrunken
some pediatricians recommend using a 10% salt solution as a nasal spray to relieve congestion in infants with stuffy noses. what effect would such a solution have on the cells lining the nasal cavity, and why?
cells will lose water because this is a hypertonic solution
carrier mediated transport
- requires specialized integral membrane proteins
- bind specific molecules
- can be regulated
facilitated diffusion
- passive transportation
- molecules too large for simple diffusion
- [high] to [low]
types of carrier mediated transport
1) facilitated diffusion
2) active transport
active transport
- movement of solutes against [gradient] (REQUIRE ENERGY ATP)
- some move multiple ions
example of facilitated diffusion
glucose
example of active transport
ion pumps
primary active transport
transport using ATP
what is an example of countertransport
sodium potassium exchange pump
secondary active transport
passive transport that uses ATP to regain homeostasis
vesicular transport
requires energy and the material moves in vesicles (bulk)
endocytosis
material enters cell
exocytosis
material exits cell
what material leaves with exocytosis
secretory products, waste
nervous system
- all neural tissue in the body
- directs immediate response to stimuli
- coordinates the activities of other organ systems
nervous system basic functional unit
neuron
central nervous system
control center
central nervous system consists of
- brain
- spinal cord
- complex integrative functions
- voluntary and involuntary
brain
- relays information to/from brain
- less complex integrative functions
- many simple involuntary activities
spinal cord
peripheral nervous system
links CNS with other systems and sense organs
enteric nervous system
walls of digestive tract
functional divisions of the PNS
afferent division and efferent division
afferent division
brings sensory info to the CNS from receptors in peripheral tissues and organs
efferent division
carries motor commands from the CNS to effectors
somatic nervous system
-controls skeletal muscle contractions
somatic nervous system consists of
voluntary and involuntary
autonomic nervous system
-regulation of smooth muscle, cardiac muscle, glandular secretions at subconscious level
autonomic nervous system consists of
sympathetic and parasympathetic
negative feedback reduces
distance from set point
examples of positive feedback
bleeding and childbirth
plasma membrane has
passive and active transport
plasma membrane is
selectively permeable
channel mediated example
LEAK channels always open
what are specific to particular ions
LEAK channels
rate of diffusion can
change by changing number of channels
what is critical to water balance in cells
solute concentration
describes effects of a solution on a cell
tonicity
isotonic
does not create a net flow of water into or out of cell
hypotonic concentrations
solute concentration outside < inside
water concentration outside > inside
hypotonic net movement of water
into cell
hypertonic concentration
water concentration inside > outside
hypertonic net movement of water
out of cell
saline
0.9% NaCl for dehydration
carrier mediated transport can be used for
regulation # of proteins and other molecules
pinocytosis
cell drinking, fluid
phagocytosis
cell eating
two key types of regulation
extrinsic and intrinsic (auto)
afferens
to bring to
effero
to bring out
types of transport
-diffusion, carrier mediated, vesicular
two functional divisions of the peripheral nervous system are the afferent and efferent divisions. what are their respective functions?
sensory input to the CNS; carries motor commands to muscles or glands
nervous system anatomical divisions
central, peripheral, enteric
functional divisions of PNS
afferent and efferent
efferent splits into
somatic and autonomic (sympathetic and parasympathetic)
neurons cell body
soma…nucleus, cytoskeleton, mitochondria, RER
neurons dendrites
extend from cell body
neurons axon
cytoplasmic process capable of propagating electrical impulse
specialized site where neuron communicates with another cell
synapse
presynaptic cell
sends
postsynaptic cell
receives
synaptic vesicles
contain neurotransmitters
synaptic cleft
separates pre- and post synaptic membranes
how do neurons communicate with each other
synapse
neurotransmitters, enzymes, lysosomes along axon
axoplasmic transport
cell body to synaptic terminal
anterograde
- synaptic terminal to cell body
- route for viral infection
retrograde
rabies bite
virus in peripheral tissues
steps of rabies
- virus infects muscle cells–multiplies
- virus enters synaptic terminals–retrograde transport
- CNS: symptoms
rabies problems
- hydrophobia (saliva glands)
- heightened aggression
cell bodies in peripheral sensory ganglia
sensory (afferent) neurons, collection neuron PNS
sensory (afferent) neurons location
between sensory receptor and CNS
sensory receptors
processes of specialized sensory neurons, or cells monitored by sensory neurons
what are the types of receptors
interoceptors, exteroceptors, proprioceptors
Somatic =
skeletal
multipolar neurons are found as
motor and interneurons
motor (efferent) neurons receive
instructions from CNS
somatic motor neurons
skeletal muscle
somatic motor neurons characteristics
-cell body in CNS and concious control
visceral motor neurons
other peripheral effectors through second set of VMN
interneurons are
most numerous type
interneurons location
brain and spinal cord between sensory and motor neurons
interneurons functions
involved in higher functions, distribution of sensory information, coordination of motor activity
neuroglia are found in
cns and pns
central nervous system contains (BLANK) cells
-astrocytes, ependymal, oligodendrocytes, and microglia
peripheral nervous system contains (BLANK) cells
-satellite cells and schwann cells
surround all axons in PNS; responsible for myelination of peripheral axons; participate in repair process after injury
Schwann
mylinate
schwann and oligodendrocytes
myelinated CNS axons; provide structural framework
oligodendrocytes
membrane potential
plasma membrane slightly negative inside
plasma membrane characteristics
-differences in permeability to various ions
plasma membrane type of transport
active
resting potential
undisturbed cell
-10 mV to -100 mV (neg)
passive forces include
chemical and electrical gradients
concentration gradient
chemical
pos and neg ions held apart, resting potential
electrical
sodium outside or inside
outside
potassium outside or inside
inside
membrane potential = charge
inside vs outside
fat membrane potential number
-40
thyroid membrane potential number
-50
neurons membrane potential number
-70
skeletal muscle membrane potential number
-85
cardiac membrane potential number
-90
how much membrane restricts ion movement (current)
resistance
change resistance by
opening and closing ion channels
sum of chemical and electrical forces acting on a specific ion across the plasma membrane
electrochemical gradient
- chemical gradient moves out of cell
- attracted to neg charge inside cell
potassium ions
equilibrium potential (no net movement) of potassium
-90 mV
- chemical gradient moves into cell
- attracted to neg charge inside cell
sodium ions
equilibrium potential (no net movement) of sodium
+66 mV
important characteristic of sodium ion
permeability low, pumped out
remove Na+ and recapture K+
active forces
active forces involve
sodium potassium ATPase
- 3Na+ for every 2 K+
- balances diffusion
cells are dynamic so
membrane potential changes
passive channels
leak, always open and permeability can change
active channels
gated, open or close in response to stimuli
graded potentials characteristic
-gated channels open, membrane potential shifts
graded potentials movement of ions
parallel to membrane- local current
degree of depolarization
decreases with distance
graded potentials do what
triggers specific cell functions
change in membrane potential consists of
depolarization, depolarization, and hyperpolarization
Na+ voltage gated channels has 3 states
open (activated)
closed (capable of opening)
closed (inactivated)
how large depolarized area is depends on
strength of stimulus and area stimulated
depolarization
shift to more + potential
repolarization
restoration of normal resting potential after depolarization
hyperpolarizaton
shift to more negative potential
what effect would a chemical that blocks voltage-gated Na+ channels have on a neuron’s ability to depolarize?
decrease/unable to depolarize because flow of sodium is what causes depolarization so this can’t occur if it is blocked
what effect would decreasing the concentration of extracellular K+ ions have on the membrane potential of a neuron?
cause hyperpolarization
remove K+ it
increases the chemical gradient and more K+ will move out of cell through leak channels
mechanically gated ion channel opens in response to
distortion of the membrane
voltage gated ion channel response to
changes in the membrane potential
example of what happens with Na+ voltage gated ion channel
- resting potential of -70mV, closed
- at -60 opens
- at +30 inactivated
chemically gated channel example
ligand gated, opens in response to presence of ACh (ligand) at binding site
Fugu puffer fish example
- tetrodotoxin is found in liver and skin
- binds voltage gated sodium channels
- paralyzed but remain conscious
- toxin produced by bacteria so non-toxic fugu can be produced
propagated changes in the membrane potential that affect an entire excitable membrane
action potential
chain reaction
-initial segment to synaptic terminals
threshold of action potential
all or none
generation of action potentials step 1
1) depolarization to threshold (-70 mv to -60)
generation of action potentials step 2
2) activation of sodium channels and rapid depolarization (-60 to 10 mv)
generation of action potentials step 3
3) inactivation of sodium channels and activation of potassium channels (10-30)
during generation of action potentials step 3
electrical and chemical gradients favor movement of K+ out of cell
generation of action potentials step 4
4) return to normal permeability (30 to -90mv) with hyper polarization
membrane will not respond normally to additional depolarizing stimuli
refractory period
cannot respond at all during
absolute refractory period
another AP can occur if sufficient depolarization during
relative refractory period
“message” is relayed from one location to another in series of repeated steps
action potential propagation
continuous propagation
unmyelinated axons (1m/sec)
saltatory propagation
- myelinated axon
- only nodes depolarize
- faster, less energy
node =
exposed axon
action potential jumps along nodes and is
less energy
large diameter (4-20um), myelinated
type A fibers
axon groups
type A, B, C fibers
- up to 120 m/sec
- sensory info (position, balance, touch, pressure)
- motor neurons to skeletal muscles
type A fibers
smaller (2-4um), myelinated
type B fibers
-ave 18 m/s
type B fibers
small (< 2um), unmyleinated
type C fibers
- 1m/s
- temp, pain, touch
- instructions to smooth muscles, glands
type C fibers
what would happen if the myelin was removed in axon groups?
lack coordination between input and output
-ex) multiple sclerosis, progressive loss of myelin across neurons (axons)
message transfer to another cell
synaptic activity
gap junctions link pre and postsynaptic membranes
electrical synapses
local currents affect other cell, not common
electrical synapses
dynamic, may be modified
chemical synapses
communication in one direction
chemical synapses
neurotransmitters classified based on effects
chemical synapses, excitatory vs inhibitory
cause depolarization
excitatory
cause hyperpolarization
inhibitory
depends on properties of the receptor (not neurotransmitter)
chemical synapses
neurotransmitters
chemicals released by presynaptic neurons into synaptic cleft
widespread, best studied neurotransmitter
acetylcholine (ACh)
cholinergic synapses
release ACh
cholinergic synapses
- all neuromuscular junctions (skeletal muscle)
- many synapses in CNS, all neuron-neuron synapses in PNS
- all parasympathetic junctions
ACh is found in
synaptic vesicles
events at a cholinergic synapse
- action potential arrives at axon terminal
- voltage gated Ca++ channels open
- ACh binds to receptors
- AChE breaks down ACh
voltage gated Ca++ channels open
- trigger exocytosis
- Ca++ rapidly removed by active transport
ACh binds to receptors
- graded potential
- action potential if threshold reached
AChE breaks down ACh
- choline absorbed into axon terminal
- acetate metabolized
synaptic delay
0.2 to 0.5 msec leads to more synapses, longer propagation time and fatigue can occur
adrenergic synapses in brain, ANS
-depolarizing inhibits hyper polarization
norepinephrine (NE)- noradrenaline
- learning, mood, attention
- inhibatory (fine control of movements)
- excitatory
dopamine CNS
lack of inhibitory neurons is characteristic of
parkinsons
- mood, appetite, sleep, muscle contraction
- inadequate production (SIDS< OCD< DEPRESSION)
serotonin (CNS and GI tract)
-inhibitory, brain
gamma aminobutyric acid (GABA)
SNDRI
reuptake inhibitor
SNDRA
releasing agent (change amt)
picrotoxin
blocks receptor
alter rate of neurotransmitter release or change response
neuromodulators
slow action on multiple neurons
neuromodulators
affect many neurons in a wider area (no one target cell)
neuromodulators
activity of receptor determines cell response to
neurotransmitter and neuromodulator action
neurotransmitter and neuromodulator action (direct)
-direct effect on membrane potential (open or close gated ion channels)
neurotransmitter and neuromodulator action (indirect)
-indirect effect on membrane potential (work through second messenger cAMP)
lipid soluble gases
bind to enzymes
Homeostasis and fever
Homeostasis acts to change the set point of body temperature and fevers are actually a useful response because heat creates a hostile environment for invaders
Net effect on membrane potential occurs in
Axon hillock
Axon hillock functions
- integrates excitatory and inhibitory stimuli
- initial segment —> action potential
Excitatory postsynaptic potential (EPSP)
Graded depolarization
EPSP open chemically gated (BLANK) channels
Na+
Inhibitory postsynaptic potential (IPSP)
Graded hyperpolarization
IPSP open chemically gated (BLANK) channels
K+
Summation
Effects of all graded potentials
Temporal
Stimuli in rapid succession at single synapse
Spatial
Simultaneous stimuli at different locations
Facilitation
Membrane potential shifted closer to threshold
Neurotransmitters include
Excitatory and inhibitory
Axon hillock
Mechanically and chemically graded potentials
Initial segment of neuron
Voltage gated channels participating in action potential
EPSP, (BLANK) MV and function
0.5 MV, sufficient depolarization causes action potential
Summation takes place at
Axon hillock
When does summation occur?
Depolarization enough for action potential signal
Stimuli in rapid succession at single synapse
Temporal
Simultaneous stimuli at different locations
Spatial
Facilitation
Membrane potential shifted closer to threshold
Farther from threshold
Inhibition
Different ways information processing takes place at neuron
Presynaptic inhibition and facilitation
Reduces the amount of neurotransmitter released
Presynaptic inhibition
Increases the amount of neurotransmitter released
Presynaptic facilitation
Key question regarding signaling?
Enough depolarization at axon hillock to generate signal?
Frequency of action potentials can change (BLANK)
Message
Greater depolarization of axon hillock results in (BLANK)
Higher frequency of action potentials
What limits action potential within given neuron?
Absolute refractory period limits # action potentials generated
Neuronal pods
20 billion interneurons- organized into functional groups in CNS
Few thousand pools
- limited number of inputs and outputs
- excitatory and inhibitory neurons
- may be diffuse or localized
Functional characteristics of neuronal pods
- divergence
- convergence
- serial processing
- parallel processing
- reverberation
Usual info sent to many parts of brain (posture and response)
Divergence
Motor neuron subject to conscious and subconscious control
Convergence
One part of brain to another
Serial processing
Many responses simultaneously
Parallel processing
Response sustained consciousness and normal breathing activities
Reverberation
Information processing occurs at level of
Neuron and groups of neurons
Complex neural processing occurs in
Spinal cord and brain
Simple neural processing occurs in
PNS and spinal cord
What is in charge of reflexes?
Simple neural processing
Rapid, automatic responses to specific stimuli with little variability
Reflexes
Reflex arc
Pathway of single reflex
Steps of reflex arc
1) activation of receptor
2) activation of sensory neuron
3) information processing by interneuron
4) activation of motor neuron
5) response of effector
Reflex generally (BLANK)
Generally removes or opposes the original stimulus
Reflex is a positive or negative feedback system
Negative feedback
Receptor
Specialized cell and sensory neuron
Steps of reflex arc from in class
1) receptor
2) sensory neuron activated
3) sensory neuron —> NT
4) motor neuron activated
5) motor neuron releases NT (neurotransmitters)
Sensory neuron —> NT
Interneuron activated, multiple inputs
Motor neuron releases NT
Stimulate effector
Classification of reflexes
- development
- response
- complexity of circuit
- processing site
Development classification
Innate (genetic) and acquired (learned)
Response classification
Somatic and visceral
Somatic
Control skeletal muscle contractions and include superficial and stretch reflexes
Visceral
Control actions of smooth and cardiac muscle and glands
Complexity of circuit classification
Monosynaptic and polysnaptic
Monosynaptic
One synapse, 2 neurons
Polysynaptic
Multiple synapses (2 to several hundred)
Processing site classification
Signal reflexes and cranial reflexes
Processing in spinal cord
Spinal reflexes
Processing in brain
Cranial reflexes
Sensory neuron synapses directly on motor neuron
Monosynaptic
Example of monosynaptic
Stretch reflex (incl., patellar, postural)
Stretch reflex
Stimulus is increasing muscle length
-counteracts stimulus, reduces chance of damage
Sensory receptors
Muscle spindles
Stretching (BLANK) frequency of action potentials
Increases
Compressing (BLANK) frequency of action potentials
Decreases
Type A fibers are
Fastest, similar to monosynaptic
Polysynaptic
Complex responses
Polysynaptic characteristics
- involve pools of interneurons
- involve reciprocal inhibition
- have reverberating circuits
- cooperate to produce coordinated response
What can affect reflexes
Higher centers
Higher centers
- descending pathways from brain modify motor patterns
- facilitate or inhibit
Polysynaptic examples
-withdrawal reflex and crossed extensor reflex
Withdrawal reflex
- flexors contract, extensos relax
- reciprocal inhibition
- versatile in response
Crossed extensor reflex
- motor response also on side opposite to stimulus
- complements flexor reflex
Reciprocal inhibition
Overrides stretch reflex
Receptors, sensory neurons, sensory pathways =
Afferent division
Receptive field
Area monitored by single receptor (neuron)
Sensory receptors
- specificity
- receptive field
- labeled line
- adaptation
One type of stimulus
Specificity
Identifies type of stimulus
Labeled line to CNS
Reduction in sensitivity
Adaptation
All information is conveyed in form of
Action potentials
Specificity example
Free nerve endings
Free nerve endings
Dendrites of sensory neurons
Free nerve endings purpose
Pain —> tissue damage, chemicals and extreme temps
How does brain determine different senses?
Has to do with labeled lines
Labeled line
Link between peripheral receptor and cortical neuron
How does labeled line work ?
Each line (group of neurons) carries info about one type of stimulus
Example of labeled lines
Rubbing eyes, brain interprets light
Where line arrives in sensory cortex determines
Perceived location
Labeled line key things
-strength of signal, duration, variation of stimulus- frequency and pattern of action potentials
Adaptation
Constant stimulus
Peripheral adaptation
Receptors activity changes
Temperature receptors are
Fast adapting
Pain receptors are
Slowadapting
Central adaptation
Pathway to CNS where sensory neuron is still active
Example of central adaptation
Smell
Example of peripheral adaptation
Temperature and pain receptors
Adaptors (BLANK) or (BLANK) receptor sensitivity or signal transmission
Facilitate or inhibit
General sensory receptors
Throughout body and are relatively simple
Classify general sensory receptors
By nature of stimulus
Most processing occurs along
Sensory pathways
Visceral
Fewer pain, temp, touch receptors and no proprioceptors
Nociceptors
Pain
Where do nociceptors occur?
Skin, joints, bones, and blood vessels
Nociceptor description
Free nerve endings with large receptive fields
Nociceptor characteristics
Temperature extremes, damage, chemicals
Nociceptor peripheral adaptation
Little
Nociceptors CNS
Facilitation, inhibition in CNS
Classification of nociceptor and chemoreceptors
By stimuli
Neuromodulators
Production of endorphins
Sensory receptors
-specificity
-receptor field
-labeled line
-adaptation
—-peripheral (receptor) or central (CNS)
Chemoreceptors characteristics
- water soluble, lipid soluble substances
- adaptation
- pH, CO2 in cerebrospinal fluid, blood
Thermoreceptors found
Free nerve endings in dermis, muscles, liver, hypothalamus
Thermoreceptors pathway
Same as pain and quickly adapt
Chemoreceptors adaptation
Peripheral and possibly central
Chemoreceptors info
No info to primary sensory Cortex
Pathway for thermoreceptors and nociceptors
Labeled lines
Mechanoreceptors stimuli
Distort plasma membranes
Types of mechanoreceptors
Tactile, baroreceptors, proprioceptors
Mechanoreceptors are
Mechanically gated channels
Proprioceptors
Position of joints and muscles, some info is conscious
Tactile
Respond to touch, pressure, vibration
-range of receptors specialized to respond to specific stimuli
Baroreceptors
-pressure changes in walls of tracts; free nerve endings
Somatic sensory pathways
- three major pathways up spinal cord
- information from skin, skeletal muscles
Three major pathways up spinal cord
- fine touch, pressure, proprioceptors
- crude touch, pressure, pain, temperature
- proprioceptors to cerebellum
Visceral sensory pathways
- interceptors
- not to primary sensory cortex
Role of major pathways
Each one caries a particular message
Pathway description
Physical pathways created by neurons traveling in a group
1st order pathway
Sensory neurons
Second order pathway
Interneurons (CNS)
3rd order neuron
Thalamus to primary sensory cortex
Pathway application to real life
Brain mapping and stimulation
-phantom limb pain
Somatic motor system
- controls contractions of skeletal muscles
- three motor pathways
- conscious motor control, subconscious regulation
Spinal, cranial reflexes
Rapid, involuntary responses
Integrative centers in brain
More complex processing
Atuonomic nervous system two main subdivisions
Sympathetic and parasympathetic
Role of autonomic ns
Routine homeostatic adjustments
Sympathetic definition
Fight or flight
-prepares body for heightened levels of somatic activity
Sympathetic regulation
Increase tissue metabolism, alertness
Decrease digestive, urinary activities
Parasympathetic definition
Rest and digest
-conserves energy, promotes sedentary activities
Parasympathetic nervous system control
Increase digestion, secretion
Decrease energy demand, heart rate
Sympathetic activation
Entire division responds
Steps of sympathetic activation
1) release of norepinephrine (NE) at peripheral synapses
2) release of NE and epinephrine (E) from adrenal medulla -hormones
- affects cells not innervated by sympathetic fibers
- effects last much longer
Release of NE and epinephrine from adrenal medulla
Sympathetic neurons
- preganglionic fiber relates ACh
- branching network of telodendria
- varicosities
- many release NE (adrenergic)
- others release ACh
- broken down by enzymes
Somatic motor system pathways
1) from primary motor cortex
2-3) from midbrain
Pathway from motor cortex
Conscious control
Pathway from midbrain
Subconscious control (muscles of trunk and proximal/distal limbs)
Sensory homunculus
Size of body part, # of sensory receptors
Motor humunculus
Size of body part, # of motor units (amt control)
If neuron is more or less likely to fire it is
Facilitated vs inhibited
If you prevent inactivation and K+ from opening then…
Depolarization can’t take place, then membrane continues to be depolarized and neurotransmitters continue to be released. A constant stimulation of muscles occurs until neurotransmitters run out. This causes a muscle lock/spasm until paralysis occurs.
Change in potential at which voltage gated Na+ channels open
Open at more positive = shift threshold away from resting potential and it is hard to reach
3 states of gates
Open (-60)
Close and active (third mem potential)
Closed and inactive (+33)
When the membrane potential is reached, what happens?
State is changed
Membrane potential of states are
Independent of each other
Varicosites
Swelling in vessel
-neurotransmitter stored and released
Sympathetic neurons simple pathway
Preganglionic fiber, ganglion (ACh), postganglionic, NE/ACh
Effects of sympathetic stimulation depends on
Receptors
Norepinephrine stimulates
Alpha receptors more than beta receptors
Epinephrine stimulates
Both alpha and beta
Adrenergic receptors are
G proteins
G proteins produce
Second messengers
(BLANK) stimulate enzymes on inside of plasma membrane
Alpha receptors
Release Ca++ from ER, excitatory effect on target cell
Alpha 1
Lowers cAMP levels, inhibits target cell
Alpha 2
Trigger changes in metabolic activity of target cell
Beta receptors
Increase in metabolic activity, increased heart rate and force
Beta 1
Relaxation of smooth muscles of respiratory tract
Beta 2
Lipolysis- release fatty acids
Beta 3
What cause vasodilation in skeletal muscles, brain
ACh and NO
Out of the alpha receptors what are more common
Alpha 1
B1
Liver
B2
Inhibit
B3
Adipose tissues
asthma inhaler has to do with
Beta 2
ACh and NO cause vasodilation in skeletal muscles, brain
Adrenergic
ACh vasodilation
Sweat glands and dilate blood vessels —> muscles and brain
NO vasodilation
Blood vessel walls—> dilation
How would a drug that stimulates acetylcholine receptors affect the sympathetic nervous system?
Widespread excitatory response, stimulates postganglionic fibers, large/widespread sympathetic response
An individual with high blood pressure is given a medication that blocks beta receptors. How could this medication help correct that person’s condition?
B1 blocked which blocks metabolic activity such as an increase in heart rate which will lead to contraction and reduce the heart rate
Parasympathetic activation
All parasympathetic neurons release ACh
All parasympathetic neurons release ACh
- effects localized and short lived
- narrow synaptic clefts
Nicotinic
Skeletal muscles, excitatory, both para and symp
Ganglion cells (symp and parasympathetic), somatic neuromuscular
Nicotinic
Open chemically Na+ gated channels
Nicotinic
Nicotine poisoning
High blood pressure, rapid heart rate
Muscarinic
Neuromuscular, neuroglandular
Muscarinic G proteins
Excitatory or inhibitory
Muscarinic changes permeability to
K+
Muscarinic poisoning
Slow heart rate, low blood pressure, constricted respiratory passages
Two types of receptors
Nicotinic and muscarinic
Sympathetic receptors
Organs and tissues throughout body
Parasympathetic receptors
Visceral structures
Dual innervation
Innervations from both and usually opposing effects
Autonomic tone
Resting level of activity
Autonomic tone function
Increase or decrease activity (gives nervous system finer control, input of information)
Example of autonomic tone
Heart function
Para vs symp autonomic tone
Parasymp dominates when at rest vs symp dominates when crisis
Examples of visceral reflexes
Pupils dilate, swallow, urination
Visceral reflexes all are
Polysynaptic
Describe visceral reflexes
Modified, facilitated, inhibited, integrated by higher centers
Long reflexes
Sensory info to CNS
Short reflexes
CNS not involved
Describe long reflexes characteristics
Processing in CNS and coordinate organ activities
Short reflexes
CNS not involved
Describe short reflexes
- autonomic ganglion
- localized control
Enteric nervous system
- walls of digestive tract
- short reflexes
- controls digestive function without CNS
Higher levels of control
Simple and complex reflexes
Simple reflexes
Rapid automatic response
Complex reflexes
Coordinated by brain
-activity in other portions of brain affect autonomic and somatic function