Animal Physiology - Exam 2 Flashcards
The Nervous system is divided into two major systems:
the central nervous system and the peripheral nervous system
The central nervous system is used for ________/_________ and is mainly in the _____ & ______ _____.
integration/processing; brain & spinal cord
the Peripheral Nervous System is made up of two major divisions:
the efferent division and the afferent division
The efferent division concerns an _____ and is going ______ ____ the CNS, it contains _____ neurons
effect; outward from; motor
The afferent division is going ______ _______ the CNS and is ________ neurons
up towards; sensory
The Efferent division is divided into two types of nervous system:
the autonomic nervous system and the somatic nervous system
What does the somatic nervous system pertain to?
Body movement via skeletal muscle
What are the two types of nervous system that the autonomic nervous system is split into?
The sympathetic nervous system and the parasympathetic nervous system
The parasympathetic and sympathetic nervous systems control
blood vessels, glands, and internal organs
What are the two subdivisions of the afferent division of PNS?
visceral sensory afferent (subconscious) and the somatic sensory afferent (conscious)
What does the visceral sensory afferent send signals from?
the signals are from sensory information from the viscera (internal organs)
What is another name for the somatic sensory afferent (conscious)
somatosensory
What does the somatic sensory afferent (conscious) send signals from?
- the signals are from the sensory information from the body surfaces (mechanical, thermal, pain/noxious) and limb/trunk position (proprioception)
- special senses (vision, olfaction, gustation, audition)
_______ cells respond to sensory _______
receptor; stimuli
What is the pathway through a receptor cell from stimuli to signal?
stimuli > selective receptor structures > intracellular amplification of signal > Neuronal signal to CNS
Pitch (tone)
depends on frequency
Pitch (tone) has the same _____ but a different _______
loudness; wavelengths (so can be a high or low note)
Intensity (loudness)
depends on amplitude
Intensity (loudness) has the same _____ but different amounts of _______
note; energy (so can be loud or soft noise)
Timbre (quality)
depends on overtones
Timbre (quality) has the same ______ and the same ____
loudness; note
the Basilar membrane is ______-________
frequency - specific
_____ frequencies are heard first in the Basilar membrane
high (are brief and look like a whip)
_____ frequencies can travel further without degredation
low (are longer and look like a wave)
At high sound frequencies, the location is the: ______, the structures are ______, _______, and _______
base (the outer part); narrower, thicker, stiffer
At low sound frequencies, the location is the: ______, the structures are ________, ________, and ________
apex (near the very inner part); wider, thinner, more flexible
Each region of the basilar membrane ______ directly to a _______ _______ of the auditory cortex in the _________ lobe
maps; specific region; temporal
If a specific part of the tonotopic map ________, person will “_____” that pitch
stimulated; “hear”
What is the range of human hearing?
between 20 - 20,000 Hz
What happens below 10 Hz and above 20,000 Hz?
Humans cannot hear
Deafness at _____ or _____ frequencies ______ the threshold for a given frequency
high or low; raises
Outer hair cells are _______ and are controlled by the ________ (__________) neurons
effectors; efferent (motor)
Outer hair cells _______ the connection with tectorial membrane which prevents ____-_______
tighten; over-movement
Olfactory receptor cells are _________ nerve endings that send _____ _______
modified; action potentials
Gustatory receptor cells are _________ cells that release _____________
Separate; neurotransmitters
Olfaction process
- Odorants bind to GPCR in cilia of receptor cells
- Action potentials sent via axon of receptor cells
- Receptor cells synapse with mitral cells in olfactory bulb
- Processed in the brain
What brain regions is olfactory information processed?
Piriform cortex, Entorhinal cortex, amygdala
the ____ of an olfactory cell has the most receptor proteins
cilia (receptor proteins localized for stimulus detection)
Ligand + GPCR binding initials graded potentials that, if large enough create: (2 things)
- A receptor potential, if large enough, becomes an action potential
- NT release onto an afferent sensory nerve
Signal transduction allows:
- Signal amplification (2nd messengers)
- Signal transformation into electrical potential
- Stimulus sensitivity tuning
The olfactory pathway
Odotrant binds to G-protein > a-G part binds to adenylyl cyclase > converts ATP to cAMP > cAMP opens Na + and Ca 2+ channel > Na + and Ca 2+ influx > Ca 2+ causes Cl - channel to open > Cl - efflux > faster/more depolarization
Vomeronasal pathway (pheromones)
- has a different 2nd messenger
- has lots of Ca 2+ influx
Gustation process
- Taste chemicals buind to taste recpetor GPCRs in tast buds in gustatory epithelium
- Taste receptor cell depolarizes and releases NTs to gustatory neurons at base of taste bud
- Gustatory neurons synapse with central neurons in brainstem then send signals to the gustatory cortex
What gustation specific ligand requires GPRCs?
- Umami and sweet require 2 GPRCs (form dimer)
- Bitter requires 1 GPRC
Gustation pathway
sweet/bitter/umami tastant binds to GPCR > activated GPCR activates phospholipase C (PLC) > PLC catalyzes conversion of PIP2 into 2nd messenger IP3 (leaving DAG) > IP3 with release of Ca 2+ from intracellular stores > Ca 2+ causes Na + channels to open and influx and ATP efflux
What is the iris
colored part of the eye between cornea and lens that regulates aperture size for light entering eye
What is the retina
neural tissue layer containing photoreceptors
Iris muscles ______ pupil diameter
regulate
Circular muscle (______/_______) and is: (two things)
(constrictor/sphincter);
1. active in bright light
2. Innervated by parasympathetic NS
Radial muscle (_______) is: (2 things)
(dilator);
1. Active in dim light
2. Innervated by sympathetic
Sympathetic stimulation causes _______ muscles to ________ which causes __ ________ and lens is _________
radial; contract; no accommodation; flattened
Parasympathetic stimulation causes ______ muscles to ______ which causes ______ and lens is _____
circular; contract; accommodation; rounded
Lens shape controlled by _____ muscle via ________: increases curvature to focus on ______ objects
ciliary; accommodation; near
Excitable cells in the retina, stimulated in order:
- Photoreceptor cells (rods/cones) respond to light directly via phototransduction.
- Bipolar cells; fine-tune rod/cone signal
- Ganglion cells; create action potentials
Rods and cones are located at the ______ of the retina
back
Rods have ______ and provide vision in ______ ___ ______, they have a _____ sensitivity to ______ and require very ______ _____ to activate, therefore they have _____ visual acuity
rhodopsin; shades of gray; high; light; little light; low
Cones have _____ ____ and respond to specific ______ of _____ (____ ____), they have a _____ sensitivity to to _____ and require ____ ____ to activate, therefore they have ____ visual acuity
cone opsins; wavelengths; light (color vision); low; light; more light; high
A cone has a ______ (smaller or larger) outer segment filled with photopigments than rods
smaller
Light is transmitted as _____ of ______
waves; photons
short wavelengths are the colors: ____ and ____ and have ___ energy
blue; violet; high
long wavelengths are the colors: _____ and ______ and have ____ energy
red; orange; low
Mammals have a photoreceptor light wave response range of _____ nm to ______ nm long
400; 700
What do cone opsins allow for an extension of ______ _______
visible range
When there is no light on the rhodopsin of a rod, the resting potential of the receptor cell sits at _____ mV which means it is relatively _________. This is because at rest, the ____ channel is open. This causes there to be a _____ of ___ onto the bipolar cell.
-40; depolarized; Na+; release; NTs
What happens to the internal potential when light hits rhodopsin of a rod?
What is the effect of NT release on a bipolar cell?
- it hyperpolarizes to reach -80 mV, this is caused by the Na+ channel to closing
- the result is reduced NT release onto the bipolar cell
In the retinal of the rhodopsin, at rest it is 11-_____-Retinal, but when light is applied, it becomes all-____-Retinal
cis; trans
What is transducin?
it is the G protein used in phototransduction in a photoreceptor cell that activates PDE (enzyme)
What alters the chemical retinal inside a GPCR?
photons in light
When photons alter the chemical retinal inside a GPCR, what happens to the Na+ channel?
it closes
What does cGMP do in signal transduction?
What occurs when light is applied?
- it holds open the Na+ channels, allowing influx and depolarization
- via metabolism with PDE (an enzyme from transducin), cGMP gets metabolized into 5’-GMP
What happens when one, tiny flash of light is applied to a photoreceptor cell?
Na+ influx stops, but the flash of light causes a really sensitive, long response. The current goes towards 0 when light is applied!
When some cGMP (opens Na+ channel for depolarization) is present, what happens to the current of the cell?
- the current was at 0, but once some cGMP is applied, there is a large influx of current until it hits -200. After cGMP is no longer applied, the current effluxes until it eventually reaches 0 again.
What are the SPECIFIC differences in phototransduction between vertebrates and invertebrates?
- vertebrates hyperpolarize when light is on, have transducin, PDE, cGMP that metabolizes to 5’-GMP (Na+ STOPS coming in)
- invertebrates depolarize when the light is on, have PIP2, PLC (enzyme), IP3 and DAG as 2nd messengers (Na + INFLUXES)
What is invertebrate light reception
- invertebrates have PLC made as the enzyme from the G-protein and that is used to stimulate PIP2 in the membrane which in turn makes IP3 and DAG. These two messengers open the Na+ channel and cause Na+ influx.
PIP2 stands for
Phosphatidyl 4, 5-bisphosphate
DAG stands for
Diacylglycerol
IP3 stands for;
Inositol triphosphate
PLC stands for;
Phospholipase C
PDE stands for
phosphodiesterase
What is the ERG? What is it used for?
It is an electroretinogram that tracks the electrical activity of the retina in response to light stimulus
What is the a wave in an electroretinogram?
it is hyperpolarization due to inhibition of dark current in photoreceptor cells, it is the first movement and it is downward on a graph; it happens immediately after light is applied.
What is the b wave in an electroretinogram?
it is the depolarization of bipolar cells, it is second wave and is significantly larger than the a wave; it happens directly after the a wave and happens while light is applied.
What is the c wave in an electroretinogram?
it is the interaction between photoreceptor cells and pigmented epithelium; this happens after the light is turned off and it is a signal that these cells are functional (bc they are wrapped around photoreceptor cells)
Across a turtle, toad, rabbit and human, how are the ERGs similar and different?
Similar:- they all have an a and b wave- the a and b wave are in the same directions as human waves
Different:- the toad and turtle have a d wave as well- there is variability in the amount of volts and milliseconds for each
What is nociception?
the detection of painful/noxious stimuli
Mechanical nociceptors are most _____, and respond to __________ damage such as: _______, crushing, and _______. These are also the _____ to respond
basic; mechanical; cutting; pinching; fastest
Thermal nociceptors respond to _________ extremes, they are enabled by _______ _____ channels that open at certain _______
temperature; TRP cation; temperatures
Polymodal nociceptors are most _____ and respond ______ to all kinds of damaging stimuli; they respond to _____ released from ______ tissues. It takes _____ to work but senses pain over a ______ ______.
complex; equally; chemicals; injured; longer; long period
_____ _____ activates nociceptors
tissue damage
What do damaged cells release?
signaling chemicals, 5-HT, bradykinin, prostaglandins
How do nociceptors send signals to the brain?
they synapse in the spinal cord with afferent neurons to the brain
What do chemicals like 5-HT, bradykinin and prostaglandins open?
cation channels on nociceptor cells and trigger APs down the dorsal root ganglion neuron
What are some characteristics of the pain response?
- initial sharp twinge of pain via the fast pain pathway
- secondary, diffuse wave of pain shortly after + occurs via the slow pain pathway
What is involved in the fast pain pathway (+ characterize it)
characterization: initial sharpe twinge of pain
Involved:
- mechanical nociceptors
- thermal nociceptors
What is involved in the slow pain pathway (+ characterize it)
characterization: secondary, diffuse wave of pain shortly after painful stimuli
involved:
- triggered by chemicals released by damaged tissue + detected by polymodal nociceptors
- prolonged pain
What is true about the nervous system across organisms?
different organisms have different structures and complexities of a nervous system, the human has a very complex nervous system while the sea star contains a neural ring and some radial nerves.
What are neural nets?
a connected series of neurons that do a specific function
What are ganglia?
a collection of nerves with an entrance and exit point for integration
What happens to the amount of branches closer to the brain?
There are more branches closer to the brain and less branches further from the brain.
What are some functions of the CNS that all mammals and vertebrates can do
1) Subconsciously regulate
2) Voluntarily control movement
3) Conscious awareness of body and surroundings
What are some other functions of the CNS that only mammals can do
4) Experience emotions
5) Engage in higher cognitive processes (thought/memory)
Monosynaptic reflex arc/loop information flow in the NS
the stimulus on tissue and travels along the axon (via neuron with cell body on outside of cell) until it reaches a synapse (central nervous system) and the NTs evoke some type of response in the postsynaptic cell. There can be a motor neuron that then releases NTs into an effector cell, common in humans
Single-cell connection of information flow in the nervous system
the stimulus hits the tissue, and dendrites are embedded into the tissue. The dendrites are connected to the soma/receptor cell and the AP is fired, it travels along the axon until the axon terminals which are attached to the effector cell
Polysynaptic reflex arc information flow in the NS
The stimulus causes dendrites in receptor cell to influence an afferent sensory neuron through APs and NTs. This then synapses on an interneuron and that synapses to an efferent motor neuron (these two neurons are part of the central nervous system), the efferent motor neuron produces some change in the effector cell.
What are the three main functional classes of neurons?
Afferent, efferent and interneurons
Afferent neurons can _____ the _______ environment and send signals to __ __ __+ some examples are:
sense; peripheral; CNS- inner hair cells, gustatory cells, nociceptors
Efferent neurons can _____ CNS information/commands to _____ organs+ one example is:
transmit; effector- motor neurons
Interneurons can _______ ______ information, coordinate ______ response, and modify both types of information content. This is only in __ __ __ and most abundant neuron type: ______ _____ neurons
integrate afferent; efferent; CNS; higher-order neurons
Interneurons are cool because:
- they have more complex/finer control and the integrator is modifying afferent information -> shows complexity of NS
A unipolar (sensory) neuron is characterized by:
- the dendrites are getting information from one area/they are embedded into one area and the dendrites are not on the cell body (cell body off to side of axon)
A multipolar (inter- and motor) neuron is characterized by:
dendrites are getting information from many different sources because they are pointing in many different directions. The dendrites are connected to the cell body and from the cell body, an AP travels down axon
What is the lateral line?
a system of sensory organs used to sense movement, vibration and pressure in the water surrounding the aquatic animal. (fish, sharks, mantas, etc.)
What can we see between the NS’s of an amphibian and mammal?
- the functional NS is preserved
What is a dermatome?
one set of spinal nerves that control one block of muscle
The evolution of the lateral line system shows that…
…as fish get more complex, the lateral line system gets more complex
The dermatome is helpful to know for ______ anatomy and NS too. We know that the function of dermatomes here is for the ______ of ____________ surfaces of the _____.
human; mapping; somatosensory; body
What are the supportive CNS cells?
Glial cells
The blood to brain must pass a _____ _____: brain ________ are sealed via _____ ______
selective barrier; capillaries; tight junctions
What are the four types of glial cells?
- oligodendrocytes
- microglia
- ependymal cells
- astrocytes
Oligodendrocytes _____ ____ sheaths for _ _ _ neurons
form myelin; CNS
Microglia ________ microorganisms, cellular _____ from dying or _____ cells, and regulate _____ networks
phagocytize; debris; injured; neuronal
Ependymal cells _____ and monitor __________ fluid that circulates ____ and ______ throughout the CNS via the __________ system
synthesize; cerebrospinal; nutrients; ions; ventricular
Astrocytes ____and establish the ___ - ____ barrier, supply _____ with compounds for making _____, and transfer ______ to neurons
regulate; blood-brain; neurons; NTs; mitochondria
What direction is the ventricular system of the cerebrospinal fluid through CNS
- it is 2-directional and keeps fresh fluid
The blood to brain must pass a _____ _____: brain ________ are sealed via _____ ______
selective barrier; capillaries; tight junctions
What are some exceptions in the blood-brain barrier?
- O2, CO2, alcohols and steroid hormones - these diffuse through the membrane bc small or lipophilic
Astrocytes also maintain _____ concentrations in ____ environment.
ionic; interstitial
Through maintaining ionic concentrations: __ _ channels (ex: Kir 4.1) in astrocytes allow __ _ in one area and then out into the _____Gene mutations for Kir 4.1 associated with _______
K+; K+; blood; epilepsy
What are the lobes of the cerebral cortex?
- occipital lobe
- temporal lobe
- parietal lobe
- frontal lobe
Through maintaining ionic concentrations: astrocytes _______ extracellular __ _ when __ _/__ _ ATP____ overwhelmed
remove; K+; Na+/K+; ATPase
What are essential anatomical parts of the brain in vertebrates?
- cerebellum
- occipital/optic lobe
- cerebrum
- pituitary
Is motor control efferent or afferent?
It is efferent
What is important about how different things like hearing, seeing, thinking and speaking are shown in brain activity?
- hearing, seeing and speaking are most active in their parts but also show activity across other lobes
- thinking shows activity across all lobes of the brain.
What are the functions of the frontal lobe?
- speech formation
- voluntary motor activity
- decision making
- elaboration of thought
Where is the primary motor cortex (precentral gyrus) found? What does it do?
It is found in the front half of the brain, in the frontal lobe
Voluntary movement
What are the functions of the temporal lobe?
- processes auditory information (tonal stuff)
- speech understanding (can tell if injury hear if speech of someone else is suddenly garbled to you)
- storing/accessing memory
What are the functions of the occipital lobe?
- initial processing of visual input
- depth-distance perception
- object and individual recognition
Is somatosensory sensation efferent or afferent?
afferent
Where is the somatosensory cortex (postcentral gyrus) found?What does it do?
It is found in the back half of the brain, in the parietal lobe
it senses touch, pain, temp
What divides the primary motor cortex and somatosensory cortex?
the central sulcus (there is some connection between the two sides, not completely separate)
What does the somatosensory cortex do in more depth?
- processes skin-based (somesthetic) sensory info
- nociceptors, thermoreceptors, mechanoreceptors
What does the primary motor cortex do in more depth?
- voluntary control of skeletal muscle
- speech production
- elaboration of thought (decision making, creativity, personality)
Both somatosensory and motor cortices are ________ in innervation, which means the ____ side of the body sends information to the _____ somatosensory cortex.
contralateral; left; right
What can we tell from comparative cortices of mammals?
some mammals have larger proportioning for some parts of the brain area, like a tarsier has a huge occipital cortex (has large eyes) whereas the rat has a huge olfactory nerve (can smell very well). In comparison, humans cannot see or smell as well.
The cerebellum is the _______ control of ______ _______
subconscious; motor activity
In the cerebellum there is _____ reception of ________ feedback from somatic receptors in _______ and ______ apparatus (inner ear). There is also ______ reception of ______ input from neurons in primary motor cortex. There is one other _______ command of _____ position (posture, _______)
afferent; sensory; periphery; vestibular; efferent; motor; neurons; motor; efferent; body; balance
Pathway for control of voluntary movements (6 steps!)
1) what type of input?
2) what happens first when you need to understand stimuli?
3) how/where does the response start?
4) What needs to happen, then?
5) Does anything additional need to happen to make sure it runs smoothly?
6)How do things continue to work/act?
1) Sensory input
2) Integration: planning & decision making center
3) Coordination: cerebellar input
4) Execution: spinal cord to skeletal muscle
5) Maintenance: posture, balance, gait
6) Continuous feedback
What are the two modes of swimming for an organism like the pink helmet jelly?
- slow rhythmic beating of bell
- rapid beats in response to mechanical stimulation
Where is the hypothalamus located?
At the top of the brainstem => evolutionarily older
What is one major hypothalamus function?
physiological setpoint storage, brain area most involved in directly regulating internal homeostasis
The brains stem controls many _____ ________ functions necessary to support life such as:
basal physiological
- cardiovascular center
- respiratory center
- swallowing center
- emesis center
- sleep center (with hypothalamus)
What are some other functions of the hypothalamus? (hint: think of regulation and coordination of body functions)
- controls body temp, urine output/thirst, food intake
- regulates hormone production
- coordinates ANS
- regulates emotional and behavioral (especially sexual) patterns
- participates in sleep-wake cycle
The cranial nerves originate in _______ and ____/_____ signals to/from ______ organs and ______ organs
brainstem; send/receive; vital; sensory
Some signals that the cranial nerve sends/receives are…
- senses (vision, audition, gustation, olfaction)
- movements of face, head, neck, throat, eyes (swallowing, chewing, salivation)
- digestive organs and heart monitoring/control
What does the spinal cord do?
- very little processing; primarily afferent/efferent movement of info
What is white matter? What is embedded in it?
It is the myelinated axon tracts and it contains the afferent and efferent tracts
Acquired reflexes are a _____ of _____ and ______
result; practice; learning
What is grey matter? What is embedded in it?
It is the neuron cell bodies, interneurons
embedded:
- dorsal horn: cell bodies of interneurons
- ventral horn: cell bodies of efferent motor neurons
What are reflexes?
muscle movements occurring autonomously in response to a stimulus
What are the two types of reflexes?
- simple (basic) reflexes
- acquired (conditioned) reflexes
Simple reflexes are _____ and _________
innate; unlearned
What are the functions of the parietal lobe?
- receive and process somatosensory input (touch, pain, temperature)
- memory formation of somatosensory experiences
What is the mechanism of a reflex arc?
1) sensory receptor - responds to stimulus
2) afferent pathway - relay
3) integrating center (spinal cord (simple), brain (acquired)) - processes available information
4) Efferent pathway - relay
5) Effector - carries out response
What are the two neuron chains in the autonomic nervous system?
- preganglionic fiber
- postganglionic fiber
The ________ fiber goes from ____ to postganglionic fiber
preganglionic; CNS
The ________ fiber goes from the preganglionic fiber to _____ ______
postganglionic; effector organ
What does the preganglionic fiber release as NTs?
always releases acetylcholine (ACh)
What does the postganglionic fiber use as NTs to control the effector organ?
- Acetylcholine (ACh)or
- epinephrine/norepinephrine (Epi, NE)
Where do the NTs of the postganglionic fiber go? What is an example of this?
onto receptors in effector organs and tissues. An example is at the neuromuscular junction where a PostG fiber meets the muscle it controls
Sympathetic nervous system has Preganglionic nerves that have what type of fibers and release what NTs?
And postganglionic nerves that have what type of fibers and release what type of NTs?
Preganglionic nerves: cholinergic fibers: release ACh
Postganglionic nerves: adrenergic fibers: release NE,
AND
cells of adrenal medulla: release Epi and NE
Parasympathetic nervous system has preganglionic nerves that have what fibers and release what NTs? And postganglionic nerves that have what fibers and release what NTs?
Preganglionic AND postganglionic nerves: cholinergic fibers: release ACh
Parasympathetic nervous system has what type of receptors in the synapse and what type in the effector in the cranio part?
Nicotinic receptor in the synapse and Muscarinic receptor in the effector(ex of effector organ: cardiac muscle)
Parasympathetic nervous system has what type of receptors in the synapse and what type in the effector in the sacral part?
Nicotinic receptor in the synapse and Muscarinic receptor in the effector(ex of autonomic effector: adipose tissue [fat])
sympathetic nervous system has what type of receptors in the synapse and what type in the effector in the thoracolumbar part?
Nicotinic receptor to alpha receptor (binds NE and E)[ex of autonomic effector: smooth muscle]
nicotinic receptor to Beta 1 receptor (binds E and NE)[ex of autonomic effector for B1 and B2: most exocrine glands and some endocrine glands]
nicotinic receptor to Beta 2 receptor(binds E only)
SNS and PNS _____ almost ____ of the ____ organs
innervate; all; same
What are the organs that the SNS and PNS innervate?
- eye
- lacrimal and salivary glands
- lungs
- heart
- liver
- stomach
- pancreas
- large intestine
- small intestine
- rectum
- bladder
- genitalia
ONLY the PNS innervates the:
spleen
ONLY the SNS innervates the:
kidney
What is an example of transduction to neuronal output from a stimuli?
stretch receptors in muscle that are stimulated/deformed when the muscle contracts (receptors on dendrite mechanically-gated), the stimuli is integrated and the graded signal converted to APs, the spike-initiating zone is further down axon and then the APs have conduction.
In a _______ afferent ending, the receptor cell is a ______ ______ of a neuron; creates its own _____ ______
specialized; modified dendrite; action potential
Sensory receptor cells are
specialized neurons
Sensory receptor cells only respond to _____ _____ (s) of stimulus and usually induce ______ ________
specific type; graded potentials
Sensory transduction is: process by which the _______ is transformed into a change in the _____ cell’s ______ ______ and its activity
stimulus; change; receptor; membrane potential
What are the four types of specialized neuron receptor cells?
A: free nerve endings
B: encapsulated (by a connective tissue capsule) nerve ending
C: sensory cell without an axon (just releases NTs)
D: peripheral processes (the soma is right under these)
What are the two categories of sensory receptor cells?
- specialized afferent ending
- separate receptor cell
In a ________ receptor cell, receptor cells are _________ and immediately release __ __s onto an ______ ____ neuron; no _______ ______ in receptor cell.
separate; depolarized; NT; afferent sensory; action potential
What step of the afferent ending mechanism is this:
voltage-gated Na+ channels open at threshold
step 2
What step of the afferent ending mechanism is this:
action potential is formed
step 3
What step of the afferent ending mechanism is this:
stimulus acts on its receptor protein in cell membrane to open nonspecific ______ channels —> ____ influxes –> receptor _____ formed
Step 1
cation; cation; potential
What does the strength of the stimulus determine in a specialized afferent ending mechanism
the strength determines the magnitude of receptor potential
What step of the separate receptor cell mechanism is this:
stimulus acts on its receptor protein in cell membrane to open nonspecific ______ channels
step 1
cation
What step of the separate receptor cell mechanism is this:
voltage-gated Na+ channels open at threshold on afferent neuron
step 5
What step of the separate receptor cell mechanism is this:
receptor cell release NT
step 3
What step of the separate receptor cell mechanism is this:
action potential is formed on afferent neuron
step 6
What step of the separate receptor cell mechanism is this:
voltage-gated Ca++ channels open -> Ca++ influx
step 2
What step of the separate receptor cell mechanism is this:
NT opens ligand-gated (=chemically-gated) ion channels on afferent neuron
step 4
What is determined by the strength of the stimulus for the separate receptor cell mechanism?
the amount of NT released
Is there a receptor potential formed in the receptor cell for the separate receptor cell mechanism?
NO
What are modalities? What are some examples?
broad categories for stimuli (temp, sound, chemical, pressure, etc.)
What are submodalities? What is an example?
the classes of stimuli within each modality. Within gustation there is sweet, salty, umami, etc.
What type of receptor is responsive to visible wavelengths of light?
photoreceptors
What type of receptor is sensitive to specific chemicals?
chemoreceptor
What are some examples of chemoreceptors?
- receptors for smell and taste
- receptors that detect O2 and CO2 concentrations in blood and chemical content of digestive tract
What type of receptor can detect changes in [solutes] in body fluids and changes in tonicity?
osmoreceptor
What are mechanoreceptors sensitive to?
They are sensitive to vibration, touch, pulling, or shape changing.
What are thermoreceptors sensitive to?
they respond to hot and cold and can also be stimulated by some chemicals (=crossmodal)
What type of receptors are sensitive to tissue damage or distortion of the tissue?
nociceptors (pain receptors)
Receptor potentials can (but not always) trigger _____ ______
action potentials
If there is a larger stimulus and large receptor potential and greater frequency of action potentials in single afferent neuron, what type of summation is it?
temporal summation
Describe the characteristics of spatial summation
- large stimulus
- multiple afferent neurons stimulated simultaneously
- all fire action potentials simultaneously
What is the difference in amount of neurons firing between temporal summation and spatial? What is the concluding similarity?
- temporal summation: 1 neuron firing a lot
- spatial summation: many neurons firing once
After all that, it still sums to the same reaction
How does the duration of stimulus affect the mechanism of coding?
- coded by tonic and phasic responses
How does the type of stimulus affect the mechanism of coding?
- depending on what receptor is activated, there will be a specific pathway through which this information is transmitted to a particular area of the cerebral cortex
How does the location of the stimulus on the body affect the mechanism of coding?
distinguished by:
- location of activated receptor field
- subsequent pathway activated to transmit this information to other area of the somatosensory cortex representing that particular location
How does the intensity of the stimulus effect the mechanism of coding?
distinguished by:
- frequency of action potentials initiated in an activated afferent neuron
- number of receptors (and afferent neurons) activated
Is fight/flight SNS or PNS?
SNS
When is SNS activated?
under specific circumstances: emergency or stressed state
What does the SNS activation do for the body? What specifically happens in the body?
- prepares body for strenuous physical activity
- skeletal muscle contraction
- cardiovascular performance
- energy breakdown prioritized
When does PNS occur?
What happens in PNS?
What specifically is prioritized in PNS?
- dominates across most of life, resting state
- promotes body maintenance
- digestion and energy storage prioritized
Is rest/digest SNS or PNS?
PNS
What does receptor type determine in SNS?
- response by effector
Any organ stimulated by SNS has ______ receptors because adrenal medulla cells and postganglionic nerves release ___/__ or just ___ which stimulates ______ receptors on effector organs/tissues
adrenergic; Epi/NE; NE; adrenergic
What are the three types of adrenergic receptors?
-alpha receptors
- beta 1 and beta 2 receptors
What do Alpha 1 receptors do?
- excite arterioles
- contraction of smooth muscle = vasoconstriction
- takes E and NE
What do Beta 1 receptors do?
- excite heart
- increased heart rate and force of contraction
- takes NE and E
What do Beta 2 receptors do?
- inhibit arterioles and lung airways
- relaxation of smooth muscle = dilation of tubes
- Only takes E to bind
Where are PNS nicotinic receptors found? What do they bind?
- on postganglionic neuron of PNS
- bind ACh from preganglionic neuron
Where are PNS muscarinic receptors found?
What do they bind?
- found on effector organs and tissues
- bind ACh from postganglionic neuron
What is the NMJ?
What will it do?
Neuromuscular junction
- it is the synapse between a somatic motor neuron and a single muscle cell (fiber)
- will release NT onto the muscle; actions of NT eventually cause contraction
What step of the NMJ mechanism is this?
ACh cross synapse and binds to nicotinic ACh receptors (=ligand-gated ion channels) on muscle cell at the motor end plate
step 3
What step of the NMJ mechanism is this?
Voltage-gated Na+ channels at edge of end plate open if EPP is large enough or lasts long enough
step 5
What step of the NMJ mechanism is this?
action potential will then propagate throughout muscle cell membrane via voltage-gated channels and spreads to multiple cells
step 6
What step of the NMJ mechanism is this?
depolarization reaches axon terminal of motor neuron
step 1
What step of the NMJ mechanism is this?
inward Na+ (or other cation) current in muscle cell creates a postsynaptic graded potential (=end-plate potential (EPP))
step 4
What must happen for the initiation of muscle action potential?
- EPP must spread from NMJ to create an AP (motor end plate, no threshold, no APs)
- the potential becomes more positive in adjacent areas
- successive opening of voltage-gated channels and action potential
What step of the NMJ mechanism is this?
Voltage-gated Ca++ channels in axon terminal open –> Ca++ influx –> exocytosis of ACh (NT) into synaptic cleft
step 2
Where are NMJ’s located on a muscle fiber?
in the middle
How does the signal from the postganglionic cell get turned off?
- Acetylcholinesterase (AChE) in postsynaptic cleft metabolizes ACh in the NMJ which prevents EPP –> relaxation of muscle fiber occurs
- Cholin transported back into axon terminal to be reused via carrier-mediated protein.
-Acetate dissolves away
What is a clinical correlation to blocking release of ACh into the NMJ?
What does this thing destroy?
- botox
- destroys docking proteins for NT vesicles – inhibits binding of NT vesicles to the membrane (+ release)
What do cholinergic receptors bind?
ACh
what are two major subtypes of cholinergic receptors?
- Nicotinic receptors (ligand-gated ion channels)
- Muscarinic receptors are GPCRs
What do adrenergic receptors bind?
What are the two subtypes?
Epi/NE
1. Alpha receptors excite smooth muscle
2. Beta receptors inhibit smooth muscle (but can excite cardiac muscle)
Skeletal muscle and cardiac muscle are both ______, while smooth muscle is _________. But skeletal muscle is innervated by the ______ NS, while cardiac muscle and smooth muscle are innervated by the ______ NS.
striated; non-striated; somatic; autonomic
What are the two major proteins in muscle fiber?
- myosin (thick)
- actin (thin)
What is important to know about myosin?
- it is the thick filaments
- they metabolize ATP to energize, then attach to actin and move actin
What is important to know about actin?
- it is thin filaments
- they are passively moved by myosin
What is the functional unit of muscle?
- the sarcomere which shortens to enable contraction
What is the myoplasm composed of?
-myosin and actin
What are actin and myosin bands?
striations
Where does contraction occur for a muscle?
in the zone of overlap between actin and myosin
What happens at the myosin heads?
- all activity
What do the myosin tails do?
they self-assemble
Myosin heads face _____, and so ____ aligns with the heads
outwards; actin
What are the two sites on the myosin heads?
What are their functions?
Actin-binding site
- attaches actin
myosin ATPase site
- attaches ATP here to be used by myosin
What are the associated proteins of actin?
Tropomyosin and Troponin
How does actin become a thin filament from actin molecules?
- actin molecules (that have binding sites for attachment with myosin cross bridge) are free floating
- actin molecules self-assemble into an actin helix with binding sites facing outwards
- then small (circular) molecules of troponin and long thin torpomyosin will attach to actin with the tropomyosin blocking the myosin binding sites on the action at REST
What are the 3 subunits of troponin and what are their basic functions?
- troponin I : binds to actin & troponin C (blocks myosin)
- troponin C : binds Ca++
- troponin T : binds tropomyosin
What happens when there is Low [Ca2+] to the troponin complex?
the troponin C is very close to the actin. Almost all myosin binding sites are blocked
What happens when there is high [Ca2+] to the troponin complex?
troponin C drifts away enough to reveal binding sites. Troponin T/I/C affinity strengthened. Way more binding sites open for myosin
What happens in rigor?
All binding sites for myosin are open. There is a stiffening of muscles. This typically happens in death because no ATP to unbind myosin.
When troponin moves, it enables what? Because of what?
cross-bridge formation
because of Ca2+
What happens in excitation?
motor neuron action potential
what happens in contraction?
sarcomere shortening via cross-bridge cycle
How does Ca++ from arteries travel to all myoplasm to bind to all troponin?
- through the T-tubules of muscle cell
- depolarized to open voltage-sensitive Ca2+ channels in sarcoplasmic reticulum
What can T-tubules do for the muscle cell?
- increase rate of AP spread along muscle cell membrane to sarcomeres
What receptor is activated by depolarization down a T-tubule lumen?
dihydropyridine (DHP) receptor
DHP will cause a change in the _______ receptor, which will ______ and cause ______ efflux into the _______
ryanodine; open; Ca2+; myoplasm
What does Calsequestrin do? With what molecule helping?
It sequesters Ca2+ and enhaces Ca2+ storage ability in sarcoplasmic reticulum WITH ATP
When does Ca2+ change in concentration and muscle contraction happen after the AP goes?
Ca2+ changes in concentration soon after AP, while muscle contraction or change in force happens once AP has become more negative (stopped) and Ca2+ is beginning to be resequestered
What is a power stroke?
What are some important properties/rules?
- when a myosin head rotates while attached to actin filament - so actin is moved toward center of sarcomere
- multiple myosin heads conducting own power strokes –> much more force
- strokes don’t happen all at once
- each myosin head goes through a lot of cross-bridge cycles
Does detachment after a power stroke occur all at once for every myosin head?
no, so that tension is maintained until full relaxation occurs
Explain the Cross-bridge cycle
- The myosin head has ADP and a phosphate on it(it is energized), it is not able to bind to the actin
- if no Ca2+, no excitation, no binding - With Ca2+ present, there is excitation and the myosin head can now bind to the actin - cross-bridge formation
- The myosin head moves actin down via a power stroke and Pi released.
- ATP is applied and the myosin actin cross-bridge is broken, assumes original confirmation
- if no ATP applied, there will be continuous attachment of myosin to actin, which will lead to rigor - Once ATP is hydrolyzed again, it will leave a phosphate and the cycle will restart
What is the length-tension relationship established by?
individual sarcomeres
At a specific sarcomere length (2.0 micrometers) and specific tension (1.0), what happens?
the optimum sarcomere length for maximum force of contraction (optimal overlap)
What happens beyond the optimum sarcomere lenght?
the muscle will generate less force because the myosin and actin no longer have optimal overall w/o enough cross-bridges (exception: cardiac muscle)
When ATP is applied to a muscle, what happens to the amount of tension?
What happens when ATP and Ca2+ applied?
What happens after there is some tension but Ca2+ is removed (via what)?
- there is no change in muscle tension
- There is an increase in muscle tension
- there is relaxation (via Ca2+/K+ ATPase) and there is a loss of tension
Force of contraction is dependent on _______ concentration present
Ca2+
As _____ concentration in myosin increases ATPase needs to ____ _____
Ca2+; work harder
If tension is increasing and ATP is removed, what happens?
Nothing
If ATP is added when tension is increasing, what happens?
tension decreases (cross-bridge detachment)
So, tension in muscles is ____ and ____ dependent
ATP and Ca2+
What is the sequence of skeletal muscle relaxation?
- Ca2+ – ATPase brings Ca2+ back into SR (against conc. gradient)
- Tropomyosin returns to resting position over myosin-binding sites
- actin filaments return to resting position as elastic fibers recoil
What are the three muscle twitch phases?
What are some characteristics of a muscle twitch?
- latent (shortest)
- contraction
- relaxation (longest)
Muscle twitches are the smallest force/tension generated by motor unit
- single APs can generate twitch
What can muscles do to increase tension?
- motor unit recruitment: multiple motor units under same command via motor neuron
- summation (temporal – multiple inputs from a single neuron – input from multiple neurons)
- length-tension relationship
What happens in a length-tension relationship?
- muscle fiber has optimal length: the overlap of myosin and actin results in max # of cross-bridges = max muscle tension
Temporal summation in muscle twitches?
Spatial summation in muscle twitches?
- single motor unit builds force of contraction bc no complete relaxation – increasing stimulus freq.
- multiple motor units recruited @ same time, bc of increasing stimulus magnitude
What are three sources of muscle ATP?
1) Production of ATP from ADP using stored Pi
2) Oxidative phosphorylation via mitochondria
3) Glycolysis in myoplasm
What is fast vs. slow twitch dependent on?
rate of ATP hydrolysis
What is oxidative vs. glycolytic fibers dependent on?
primary route of ATP production
With phasic muscles, what is the AP and twitch?
- all or none AP and muscle twitch
With tonic muscles, what is EPP and contractions?
- summation and facilitation of EPPs, graded muscle contractions
Where is smooth muscle found?
What does it do?
What is its Ca2+ binding protein?
What are its three types of filaments?
- walls of hollow organs and tubes
- executes rhythmic/repeated slow, forceful contractions
- contains calmodulin
filaments:
1. myosin filaments
2. actin filaments
3. intermediate filaments : no contraction role, supports cell shape
What is the mechanism for smooth muscle contraction?
- some stimulation, Ca2+ channel open, Ca2+ in
- Ca2+ influx, opening of Ca2+ channels in SR –> more Ca2+ in myoplasm
- calmodulin swaps Pi for Ca2+ –> now active
- CaM-Ca2+ activates MLCK (myosin light chain kinase)
- MLCK uses Pi from ATP to activate myosin light chain of myosin neck
- Now active, myosin can form cross-bridge with actin –> ^ tension development
What are the two smooth muscle types?
how do they differ?
- multi-unit smooth muscle: individual cells that function independently
- single-unit (visceral) smooth muscle: multiple cells, share single stimulus, one big unit
How are the smooth muscle types stimulated?
- Multi: individually stimulated by A nerves : neurogenic
– ex: walls of large BV, bronchioles, iris - Single: self-excitable = myogenic, cells linked by gap junctions to spread AP cell to cell
– ex: hollow organs of digestive, urinary, reproductive
Explain a pacemaker potential
it is the automatic resumption of depolarization, there seems to be no stable resting potential
Explain a slow-wave potential
under the threshold, there is a slow wave of potential, but once passing threshold, a sequence is fired off bc of nervous system or environment stimulus command
How is cardiac muscle similar to skeletal muscle?
- striated (thick/thin filaments)
- T-tubules and SR
- Ca2+, troponin, tropomyosin for cross bridge stuff
- length-tension relationship
- abundant mitochondria and myoglobin
How is cardiac muscle similar to smooth muscle?
- Ca 2+ enters cytosol from ECF (and SR)
- Pacemaker activity
- interconnected by gap junctions
- innervated by autonomic nervous system
