#2 lecture Flashcards
Sensory receptors are specialized to
Specialized to respond to changes in environment, a.k.a. stimuli
Activation of a receptor by an adequate stimulus results in
Results in graded potential that trigger nerve action potential along PNS fibers
Sensory receptor neurons can be classified by
① stimulus
② location in body
③ structural complexity of dendrites
Sensory receptor, neurons provide
Provide information regarding following classes of stimuli (general and specialized senses)
Sensory integration
Processing of signals recognize consciously a.k.a. information that reaches the cortex
Somatosensory cortex is the primary __
Primary side of integration of general senses from the exteroceptors, interceptors, and proprioceptors from body/ limbs
Additional zones are responsible for?
Responsible for specific special senses tied into sensory organs (Visual cortex )
Two concepts of sensory integration
. Sensation and perception.
Sensation
Awareness of changes in the environment ( stimuli)
Perception
Conscious interpretation of the stimuli and it’s consequences
Integration (Sensory integration)
Determines how we respond and or interpret environment
Response (Sensory integration)
Execute the needed action to resolve the need/decision
Three levels of sensory integration to achieve both sensation and perception
① receptor level
② circuit level
③ perceptual level
Receptor level
For sensation to occur stimulus must make enough graded potential to send action potential
-generator potential = graded potential (general senses)
-Receptor potential = graded potential(special senses)
phasic receptors (receptor level)
Fast adapting, often giving burst of impulses at the beginning and the end of the stimuli
- photoreceptors adjust to light
- pressure receptors and touch
Tonic receptors (Receptor level)
Provide a sust(ained response with little or no adaptation
- nociceptors an proprioceptorS, due to protective importance of information
Higher level levels and receptor level can adjust from
(Circuit and perceptual level )
Adjust from top down
-Pain tolerance, reticular formation
Circuit level (Sensory integration)
Task is to deliver impulses to appropriate region of the cerebral cortex often and relays that allow:
-Some filtering along the way and lower brain areas
-Some interaction with spinal cord reflexes
How does circuit level work?
Sensory neurons send their signals along tracks to their location with the goal of getting to the cortex
-however, circuits are often arrange and realize that allow the signal to be branched to other regions along the way
-Allow more processing and interaction, including involuntary areas
Perceptual level (Sensory integration)
Processing in cortex areas were info is compared and interpreted to allow motor response
-Context is taken into account
How does perceptual level work?
Inner neurons in the cortex receive signals from numerous different receptor neurons and takes more into account beyond just if a stimulus was detected
-Once info is processed/interpreted signals are sent to appropriate motor response pathways
Perception and response depends on?(Sensory integration. )
Depends on sending information back-and-forth between interns
Cerebrum
Made of two cerebral hemispheres, which have three main regions
83% of brain mass
Made of suici and gyro that increased surface area
Three main regions of cerebrum
Cerebral cortex (Gray matter)
Basal nuclei (gray matter)
White matter ( tracts connect areas)
. cerebrum has tracks of.? (Perception / integration areas)
White matter that connect
-Provide connection to different brain areas can talk to each other
-Association fibers
- commissural fibers
-projection fibers
Association fibers (Cerebrum)
Connect different lobes of the brain
commissural fibers (cerebrum)
Connect hemispheres (Corpus callosum is the major one)
Projection fibers (Cerebrum )
Connect the cerebrum to lower areas of the brain and spinal cord
’ commissural and projection fibers connect?
Connect opposite sides of the nervous system and play an important role in crossing over (Decussation )
Decussation, crossing over in our nervous system
Crossing over of tracks from one side of the nervous system to other during their neural circuit wiring
-90% of sensory/motor output crossover
-Right body controlled by left brain
-Left body controlled by right brain
What is between hemispheres of the brain?
Cerebral lateralization
Corpus callosum
-major bridge between cerebral hemisphere‘s for perceptual communication
Commercial fibers play in an important role in keeping the left and right info coordinated during perception
All motor (efferent) divisions of the peripheral nervous system have?
Reflexes and they all follow the same general reflex arc strategy
Reflex responses
Involuntary motor responses to stimulate that does not require thinking
-Somatic deal with skeletal muscle
, - autonomic deal with visceral organs
Fast acting of reflex response
Evolved her responses that require quick changes in physiology
-Reduce damage, maintain balance
Predictable reflex response
Responses are stereotypes to repeat a required function
Reflex response process
① Receptor: site of stimulus action
② sensory neuron: transmit afferent impulses to CNS
③ integration center ( monosynaptic,polysynaptic)
④ motor neuron: efferent impulse to effector muscle and organ
⑤ effector: muscle fiber or gland cell respond to impulse by contracting ol secreting
Monosynaptic reflex
Sensing neuron synapses directly w/ motor neuron
Polysynaptic reflex
Interneurons are involved in signal relay circuit
In somatic, nervous system motor neurons move through?
Plexus (below head)
Plexus (somatic nervous system )
Neurons from different spinal nerves are sorted and recombined so that all fiber is going to a specific target or put together in one nerve branch
Most somatic responses are handed by
Plexuses
Thoracic spinal nerves do not form?(Somatic nervous system. )
Do not form big plexus and instead branch into targets of the sympathetic nervous system system, a different motor division
. Efferent neuron mostly relay.?(somatic nervous system )
Mostly relay voluntary control
Where does the somatic nervous system carry signals from?
Carry signals from the CNS and relays info to skeletal muscles for predominantly voluntary control and for some involuntary reflexes
Withdrawal reflex (somatic reflexes )
Pain reflex to quickly draw limbs back from harm
Diaphragm/intercostals (somatic reflexes)
Muscles for contraction/relaxation and breathing are skeletal muscles that pass via cervical plexus/ phrenic nerve
Proprioreceptors reflexes (Somatic reflexes)
Sense stretch/strain and skeletal muscles to unconsciously control movements to prevent damage
Capsule (Somatic reflexes -stretch responses ).
Spindle shaped dendrites are surrounded by intrafusal fibers, enclosed in o connective tissue
Where are proprioceptor present?(Somatic reflexes.)
Present throughout the paramecium that wraps fascicles of skeletal muscles
Mechano receptors (somatic reflexes -stretch responses)
Response to stretch in the muscles and are involved in somatic reflexes
Muscle spindles help resist?(Somatic reflexes.)
. Help resist over stretching
Knee-jerk reflex is a?
Stretch response
Capsule (Somatic reflexes -relaxation responses)
Small bundles of sensory terminals coiling around fibers within a layer capsule
Proprioreceptors (Somatic reflexes relaxation responses )
Present throughout tendons, at the junction between the tendon fibers and skeletal muscles
Mecano receptors (somatic reflexes relaxation responses )
Respond to stretch in tendon fibers and are involved in relaxation reflexes
Tendon organs help to resist?(Somatic reflexes relaxation response. )
Resist over contraction
-Connections to skeletal muscles detect when a muscle attracts too much
How do tendon organs help to resist over contraction
Trigger a reflex that relaxes the contracted. muscle
tendon organ axon also has a branch that synapsis/triggers, reciprocal activation in order to contract and antagonistic muscle
-Does the opposite proprioceptor monitoring as the muscle spindle stretch response
Medulla oblongata and pons (ANS )
. Receive info for visceral receptors to monitor cardiovascular and breathing systems
Hypothalamus (ANS )
Receive sensory info to regulate many processes
-Contain many sensory receptors which monitor concentration of body fluids, internal temperature, etc.
, ANS controls many targets that we are not in conscious control of adjusting
Involuntary nervous system
Smooth muscles (organs/vessels )
Cardiac muscle (heart contraction)
Glands (Endocrine system )
Motor signals heading out through ANS divide between
Between parasympathetic and sympathetic division
Sacral nerves ( parasympathetic division)
Send preganglionic neurons to pelvic regions
-They are not the rami
Somatic is ___ step relay
1
ANS is __ step relay
2
Somatic System
Motor neurons that go to effectors (skeletal muscle) do it in a single step with no synapses in the PNS
ANS system
Motor neurons that go to effectors have two step motor neuron relay, such that there are synapses in the PNS
Are motor ganglia present in ANS?
Yes
Are there motor ganglia present in somatic system
No
Where are motor ganglia present in sympathetic
Close to spinal cord and far from targets
Where are motor ganglia present in parasympathetic
Far from spinal cord and close to targets
Myelination in somatic system
Entire motor neuron is usually very heavily myelinated leading to faster signals
Myelination in ANS
preganglion are lightly myelinated leading to slower signals
-postganglion are non myelinated leading to slower signals
Postganglion neurotransmitters in somatic system
Motor neurons that wire to skeletal muscle all release Acetylcholine, causing stimulation of muscles so that they contract
Postganglion neurotransmitters of ANS
postganglion neurons can either release acetylcholine or norepinephrine, which can have either stimulatory or inhibitory effects depending on the target
In postganglionic neurons, sympathetic neurons use….
Norepinephrine
In postganglionic neurons, parasympathetic neurons use…
Acetylcholine
Why do sympathetic and parasympathetic systems need to have different neurotransmitters
They have to balance or oppose each others responses
How do neurons generate different physiological responses
Chemical messengers and their receptors are more complex and varying in the ANS
Cholinergic receptors
Protein receptors that bind to ACh and there are types
2 types of cholinergic receptors
Nicotinic an muscarinic
Nicotinic
Always stimulatory
-dendrites of postganglionic cells
-skeletal muscles sarcolemma
- adrenal medulla
Muscarinic
Either stimulatory or inhibitory effects depending depending on the sub class of receptor in target
-all parasympathetic targets
Norepinephrine and related epinephrine are utilized mainly within …
Sympathetic division
- secreted by postganglionic cells
- secreted by chromaffin cells of the adrenal medulla
Adrengic receptors are either …
Stimulatory or inhibitory depend on type of receptor in target
- alpha receptor (a1 and a2)
- beta receptors (b1, b2, b3)
Varicosities
Swellings along postganglionic neuron axon terminals release chemicals
- infilitrate dif tissues to release amounts of chemical messengers
Messengers are either …. (Varicosities )
Neurotransmitters: if stays in synapse region
- hormone : if instead enters bloodstream
Gland
Group of cells that secretes one or more products
What do glands generally begin as
Epithelial tissue
Adrenal glands connect to..
Preganglionic neurons of sympathetic division
How are some connections made in the adrenal gland
Some connections are made in which there is no formal ANS ganglion, where the pre-ganglion neurons go directly to the adrenal gland
Adrenal synapses
Preganglion neurons synapse directly w/ secretory chromaffin cells in adrenal medulla
- chromaffin cell releases N/EN directly into bloodstream, makes hormones
Hypothalamus is a key link btwn
ANS and endocrine system
Nervous system
High speed, electrical signals along specialized neurons
-signals regulate or control other cells
-fast responses needed due to changing environment
-somatic, and autonomic nervous system
Endocrine system
Secrete hormones that coordinate slower but longer acting responses, including
-reproduction, development, growth, metabolism, behavior, and immunity
Endocrine glands
Ductless glands that produce hormones and lack ducks
-release hormones into surrounding fluid
-rich, vascular drainage
-branching networks
-pituitary, thyroid, parathyroid, and adrenal penal glands
Neuro endocrine organ
Neural and hormone function and example hypothalamus
Organs
Several organs also have special subdivisions of secretary, endocrine glands
-pancreas, gonads, and placenta
Signaling molecules
Each chemical binds a specific receptor
Although a signaling molecule can reach different cells throughout the body…
Only some cells will have a receptor that fits that molecule
How do signaling molecules work?
Has a target cell that has receptors that combined specifically to its 3-D shape
How can distinct response pathways be activated under different conditions?
Signaling molecules
Hormones
Secreted, chemical, messengers and endocrine system
Steroid hormones
Derived from cholesterol
-Cholesterol as a precursor molecule
-steroid hormones come from gonads or the adrenal glands
-generally lipid soluble
Amino acid hormones
Range in sizes, but all includes some form of modified amino acids or peptides
-generally water soluble
-most hormones are this type
Small amino acid hormones
Simple amino acid derivatives also nitric oxide
Medium amino acid hormones
Short chains of amino acids, an example peptides
Large amino acid hormones
Complete/complex translated proteins
Are hormones produced in one body region
Yes, and they have effects in other regions
Are hormone/signaling molecules, chemical messengers
Yes, they are secreted into bloodstream or into interstitial fluid to communicate signals to organ systems
Do hormones/signaling molecules reach all parts of the body
Yes, but only target sells respond due to specificity of receptors
Where are hormones distributed in endocrine?
Circulatory system
Where do hormones reach in endocrine system?
Reach target cells by entering a circulatory system like the bloodstream or lymphatic system
Where are hormone/signaling molecules produced in endocrine system
Produced by ductless glands
Longer acting with broad effects of hormones/signaling molecules
Circulate in body for a while
-Mediate long-term responses
-growth and development, chronic responses to environment and immune response as well
Paracrine(hormones/signalng molecules)
Local regulators that act on neighbor cells
Where are paracrine signaling molecules produced
Not produced by special dedicated glance, but are secreted from cells and tissues and organs response to local stimuli
Why are paracrine called local regulators?
They moved by diffusion to induce very rapid responses within tissues
How does paracrine communication between neighbors help
Help organs respond as a unit
And example prostaglandins with rapidly trigger local immune response responses
Autocrime (hormones/signaling molecules)
Secreting cells are themselves to target
How are autocrine’s signaling molecules produce?
Produced by a cell and then our self detected by receptors on the cells own membrane
Are autocrine hormones usually in positive feedback
Often and positive feedback to help amplify responses
-need a circuit breaker to interrupt the runway response
Can some signals be both paracrine and autocrine
Yes, to boost signal
Where are neurotransmitters secreted?
Secreted directly by neurons
What are neurotransmitters(hormones/signaling molecules)
Signaling molecules secreted by membrane regions were neurons interact, called synapses
What does a stimulated neuron release?
Release note transmitters into the space between cells
an example synapse
Does neurotransmitter diffuse short distance
Diffuse short distances to target sell rapidly triggering another electric impulse
Neurohormones
Neuronal hormones that enter blood
What do neurohormones release?
Special brain or ANS neurons release chemical messengers that become hormones because they enter/travel in the bloodstream
Where are neurohormones used?
Used in neural endocrine, signaling in the hypothalamus/pituitary gland to signal and control large responses
-water balance hypothalamus
-temperature hypothalamus
-sexual development pituitary
Is Norepinephrine released in a general gland?
Yes
Pheromones
Chemical secreted outside the body
Where are pheromones secreted from?
Secreted from glands that act outside of the body
Where are pheromones produced?
Produced by one individual in order to change the behavior and physiology of other individuals
-species recognition
-social interaction and reproduction
-navigation and territory marketing
Do hormones vary in their solubility
Yes
Water soluble(hormones )
They do not pass easily through membranes so receptors are on outer cell membrane
-amino acid based hormones(usually)
Lipid soluble(hormones)
Past easily through cell membranes so receptors are often inside the target cell
-steroids(usually)
Three key events in hormone signaling
Release migration and response
- Release.(hormone signaling.)
Cell/gland receives a stimulus and releases signal
- Migration.(hormone signaling.)
Message is carried via bloodstream in this example
- Response(hormone signaling.)
Target sells them respond to the hormone
Signal transaction pathway
Chain of events that leads to intracellular response
- cytoplasmic responses, enzyme, activation, and gene expression changes
What do water soluble hormones often need
Secondary messengers for the signal to cross membranes
Where will lipid soluble hormones often enter?
Often directly enter the nucleus to act as transcription factors that induced changes in gene expression
-there is not an official second messenger
With so much hormone being released, why don’t all tissues respond
Not all cells expressed the same receptors nor do all cell types respond in the same way
Hormone responses summary
Although hormone circulate broadly not all cells respond the same way
-different receptors can detect the same hormone
-same receptor can activate distinct signal, transduction pathway among different cell types
-multiple responses can be generated via the use of a signal hormone
It is not always about switching between the emergency and nonemergency situations…
Often it is also about maintaining balance between systems to keep internal condition stable
Homeostasis
I regulation that keeps an internal condition
Does endocrine system play an essential role in homeostasis?
Yes, or maintaining a study day regardless of external environment
What is a primary control center for homeostasis?
Hypothalamus it links with pituitary gland to control homeostasis of numerous physiological states
-body temperature blood pH glucose
Negative feedback oops
Systems help return a variable to within a normal physiological range or a steady state setpoint when the internal conditions are upset
-signal is inverted to turn the system around
Most control systems used to maintain homeostasis operate using
Negative feedback
Hormone pathway, employing negative feedback
Blood glucose homeostasis
Insulin and glucagon
Antagonistic hormones that maintain glucose homeostasis
Pancreas has clusters of…(homeostasis)
Adult crying cells called islets of langerhans
-alpha cells produced glucagon
-Beta cells produced insulin
Type one diabetes
Auto immune disorder
Type two diabetes
Chronic adaptation
How do hormones travel for negative feedback loop
Released from endocrine cell travel through bloodstream and interact the receptor of a target cell to cause a response
-then a negative feedback loop inhibits a response by reducing the initial stimulus
Positive feedback loops
External stimulus triggers, a physiological response that reinforces and amplifies that same response so the system keeps increasing its output away from the set point
-unstable if not controlled
External signal
Usually must break the lip or else positive feedback loops can become pathological
Hormone cascade pathways
Hormone can stimulate release of other hormones
How can one hormone stimulate the release of other hormones?(hormone cascade pathways.)
But the last hormone in the stepwise cascade activating non-endocrine tissue to make the physiological response
Tropic hormones(hormone cascade pathways)
Act indirectly by stimulating other endocrine glands
Non-tropic hormones(hormone Cascade pathways)
Act directly by stimulating response in non-endocrine target
Is oxytocin and ADH non-tropic or tropic
Non-tropic
Why is the pituitary gland often called the master endocrine gland
Because it’s both part and directly tied to the hypothalamus
Does parathyroid gland release non-tropic hormones
Functions with moral stimulus to release non-tropic parathyroid hormone
How is growth Limited?
Negative feedback loops
How does negative feedback loops control growth hormones
Ensure that growth is regulated properly while still allowing use of GH in the daily metabolism
What does high levels of GH stimulate?
Stimulate the release of somatostatin GHIH from many digestive tissues in the pancreas, delta cells
- important monitoring point due to the insulin glucagon system
Somatostatin GHIH inhibits…
The release/the production of growth hormone release hormone from the hypothalamus
Improper level levels of GH can result in…
Abnormalities with broad
Hypersecretion
Growth plates are overly stimulated, resulting in forms of gigantism
- during childhood excessively tall
-during adulthood, disproportionate limbs
-often due to tumor on anterior pituitary
Hyposecretion
An adult it is usually not symptomatic, however
-During childhood lead to dwarfism
-slows, long bone growth other effects
Metabolism, short-term growth hormone
Directly, target broad tissues, and sells to grace, blood glucose and increase metabolism
-influence, blood sugar levels
-stimulate, fat and glycogen breakdown
-stimulate amino acid uptake
- assist with thermal regulation
What does GH follow to make sure we have blood sugar homeostasis?
Circadian clock
How fast is during menopause are likely due to…
Low estrogen levels, causing rapid stress response
What triggers, hot flashes
As levels drop below lifetime setpoint ovaries cannot easily bring levels back up
-trigger, sympathetic division stress response in the hypothalamus
-mobilize high activity mechanisms
-include dialatatingcapillaries of skin
Is sympathetic, short-term or long-term
Short term
Is pituitary short term or long-term?
Long-term a CTH
Is short term non-tropic or tropic
Non-tropic
Is long-term tropic or non-tropic
Usually tropic pathways with multiple hormone Caid steps
Chronic activation, long-term adrenal gland
Hypothalamus communicates via
-Portal system to interior pituitary
-releases ACTH hormones
-stimulates adrenal cortex
-releases cortisol
What is a Reflex Response? What are two types?
A Reflex Response is an automatic reaction to a stimulus. The two types are Somatic and Visceral.
What are the different types of Somatic Reflex Responses?
The types of Somatic Reflex Responses are Intrinsic and Learned.
What are the 5-steps of a general Reflex Arc?
- Stimulus 2. Receptor 3. Afferent pathway 4. Integration center 5. Efferent pathway 6. Effector.
Typically, what does the Somatic Division of the PNS control?
The Somatic Division of the PNS typically controls Voluntary Movement.
Does the Somatic Division control some involuntary functions?
Yes.
List some important Involuntary Reflexes controlled by the Somatic Division.
Important Involuntary Reflexes include the Knee-jerk reflex and withdrawal reflex.
What are Proprioceptors, and where are they located? What do they monitor?
Proprioceptors are sensory receptors located in muscles, tendons, and joints that monitor body position and movement.
How does The Stretch Reflex work, using Muscle Spindles? Why is it important?
The Stretch Reflex works by detecting muscle stretch through Muscle Spindles, which helps maintain posture and balance.
How does The Tendon Reflex work, using the Golgi Tendon Organ? Why is it important?
The Tendon Reflex works by detecting tension in muscles through the Golgi Tendon Organ, preventing muscle damage.
Why are ‘involuntary’ reflexes like the Muscle Spindle Reflex not part of the ANS?
Because they wire to Skeletal Muscle, and therefore are part of the Somatic Division.
What responses does the Autonomic Nervous System (ANS) control?
The ANS controls Involuntary responses.
What are the differences in Targets between the Somatic Nervous System and the ANS?
The Somatic Nervous System targets Skeletal Muscles, while the ANS targets Smooth Muscles, Cardiac Muscles, and Glands.
What are the two divisions of the Autonomic Nervous System?
The two divisions are the Sympathetic Division and the Parasympathetic Division.
What are some key differences between the Somatic Nervous System and ANS?
Key differences include control (voluntary vs. involuntary), targets (skeletal vs. smooth/cardiac), and pathways.
Where do cell-bodies of motor-neurons in the Parasympathetic Division come from?
They come from the brainstem and sacral spinal cord.
Where do ganglia of motor-neurons in the Parasympathetic Division typically reside?
They typically reside near or in the target organs.
How long are preganglionic and postganglionic neurons in the Parasympathetic Division?
Preganglionic neurons are long, and postganglionic neurons are short.
Approximately how much of the Parasympathetic Division does CNX supply?
CNX supplies approximately 75% of the Parasympathetic Division.
Where do cell-bodies of motor-neurons in the Sympathetic Division come from?
They come from the thoracic and lumbar regions of the spinal cord.
Where do ganglia of motor-neurons in the Sympathetic Division typically reside?
They typically reside close to the spinal cord in the sympathetic trunk.
How long are preganglionic and postganglionic neurons in the Sympathetic Division?
Preganglionic neurons are short, and postganglionic neurons are long.
Which ANS Division has cell bodies in the lateral gray horn of the Spinal Cord?
The Sympathetic Division.
What are Sympathetic Trunk/Chain Ganglia? Where are they located?
Sympathetic Trunk/Chain Ganglia are clusters of nerve cell bodies located alongside the vertebral column.
