BIOL 223 Lecture final Flashcards
Transduction
How a stimulus is converted into an action potential
Free Nerve Endings
Simplest receptor type. Dendrites directly imbedded in tissue
Encapsulated Nerve Endings
Dendrites encased in connective tissue which enhances their performance
Specialized Receptor Cells
Respond to very specific stimuli. For example, photoreceptors in eyes. Only respond to light
Exteroceptor
Receptors located near an external stimulus such as in the dermis.
Interoceptor
Internal organs and tissue, blood pressure regulators
Proprioceptor
Located near motor functions, Muscle and tendons
Adaptation
Reduction of receptor sensitivity in the presence of a constant stimulus
Tonic Receptors
Always active and show little to no adaptation (e.g. pain)
Phasic Receptors
usually inactive and show burst of activity followed by rapid adaptation (e.g. Temperature)
Chemoreceptors
Detects chemicals. Blood Ph, Taste
Osmoreceptors
Detect Osmolarity changes in body fluids. Dehydration.
Nociceptors
Pain receptors. Stimulated by chemicals released from damaged tissue.
Mechanoreceptors
Respond to physical stimuli
Thermoreceptors
Heat receptors - temp above normal body temp. Cold receptors - temp below normal body temp. Extreme temperatures active nociceptors
Gustation - Taste
Provides information about foods and liquids consumed. Taste, texture
Filiform Papillae
Provide friction to move food around the mouth. No taste buds
Fungiform Papillae
Contain about 5 taste buds each
Vallate Papillae
Contain as many as 100 taste buds each. Majority of taste buds located here
Explain how receptor potentials are formed for the primary taste - Sweet
Bind to G-Protein coupled receptor
Explain how receptor potentials are formed for the primary taste - Salty
Na+ generate receptor potential
Explain how receptor potentials are formed for the primary taste - Sour
H+ generate receptor potential
Explain how receptor potentials are formed for the primary taste - Bitter and Umami
bind to G-protein coupled receptor
Discuss the taste projection pathway
Cranial Nerves VII Facial nerves, IX Glossopharyngeal, and X Vegas carry sensory information (1st order Neurons)
Synapses on 2nd order neurons in medulla oblongata
Synapse on 3rd order neurons in thalamus
information carried to the primary sensory complex.
Olfactory Sensory Neurons
Highly modified bipolar neurons. Detect dissolved chemicals as they interact with odorant-binding proteins
Describe the production of a generator potential for olfaction
begins with binding of odorant to G-Protein coupled receptor
Creates generator potential (depolarization)
Synapse with neurons in olfactory bulb
Olfactory cortex- temporal lobe
limbic system
Hypothalamus
External Ear Components
Auricle (Pinna), Tympanic Membrane (ear drum), Ceruminous Glands
Auricle (Pinna)
Surrounds and protects auditory canal
Tympanic Membrane (ear drum)
Thin, Semitransparent sheet. At end of external acoustic meatus. Separates external ear from middle ear
Ceruminous Glands
Trap debris. Maintain playability of tympanic membrane
Middle Ear Components
Air-filled chamber (tympanic cavity of temporal bone), Communicates with nasopharynx through auditory tube, Contains three tiny ear bones (auditory ossicles)
Malleus (hammer)
Articulates with tympanic membrane
Incus (anvil)
Inbetween Malleus and Stapes
Stapes (stirrup)
Articulates with the oval window
Inner Ear Components
Bony labyrinth surrounds and protects membranous labyrinth, Perilymph flows between the two labyrinths, Endolymph is within membranous labyrinth
Vestibule
Inner Ear. Encloses saccule and utricle, Receptors detect gravity and linear acceleration
Semicircular canals
Inner Ear. Three. Receptors stimulated by rotation of head.
Cochlea
Contains cochlear duct of membranous labyrinth, Receptors provide sense of hearing
Explain the process of hearing
Sound waves are converted into mechanical movements by vibration of tympanic membrane, Auditory ossicles conduct vibrations to internal ear, Vibrations are converted to pressure waves in fluid which are detected by hair cells in the cochlear duct, Information is sent to auditory cortex in brain
Equilibrium
State of physical balance
Structures associated with Equilibrium
Sensations provided by receptors of vestibular complex (vestibule and semicircular canals)
Utricle and Saccule - sense head position
Semicircular canals - sense head movement
Utricle & Saccule
Hair cells provide sensations of position and linear movement
Maculae
Macula of utricle senses horizontal movement
Macula of saccule senses vertical movement
Otoliths
Densely packed calcium carbonate crystals on surface of gelatinous mass
Structure of the semicircular canals
Connects with vestibule at the ampulla
hair cells positioned within ampullary cupula
Nociceptors
receptors for pain. Free nerve endings with large receptive fields
Neurotransmitters are glutamate and or substance P
Fast Pain
Deep Cuts, Injections
Signal sent to the CNS rapidly and to the primary somatosensory cortex for conscious perception
Slow Pain
Burning or aching pain
Signal Sent more slowly
vague awareness of pain but not localized
receptors for temperature
Free nerve endings
Sensations are conducted along same pathways that carry pain sensations
sent to reticular formation, thalamus, and (to a lesser extent) the primary somatosensory cortex
mechanoreceptors
Sensitive to physical stimuli that distort their plasma membranes
Membranes contain mechanically gated ion channels that open or close in responce to the physical distortion:
Pacinian corpuscles
Meissner’s corpuscles
chemoreceptors
Respond to water - and lipid-soluble substances that are dissolved in body fluids
Exhibit peripheral adaptation in seconds
Monitor pH, carbon dioxide, and oxygen levels in arterial blood in internal carotid arteries and the aortic arch
Eyelids
A continuation of skin
Blinking keeps surface of eye lubricated and clean
Palpebral fissure
Space between eyelids
Eyelashes
protective, prevent debris making contact with eye
Tarsal glands
Secrete lipid-rich product that helps keep eyelids from sticking together
Lacrimal caruncle
mass of soft tissue at medial angle of eye
Conjunctiva
Mucous membrane covered by an epithelium
Palpebral conjunctiva covers inner surface of eyelids
Bulbar conjunctiva covers anterior surface of eye
Conjunctivitis (pink eye)
Inflammation of conjunctiva
Lacrimal Apparatus
Produces, distributes, and removes tears
Lacrimal gland (tear gland)
Produces tears that bathe conjunctival surfaces
Secretions contain lysozyme (antibacterial enzyme)
Fornix
Pocket where palpebral conjunctiva joins bulbar conjunctiva
receives 10-12 ducts from lacrimal gland
Describe how the pupillary diameter is changed
When the pupillae dilator contracts the pupil gets bigger. Decreased light intensity allows more light into eye..
when the sphincter pupillae contracts the pupil gets smaller. Increased light intensity less light in.
Rods
Photoreceptors. Modified epithelial cells.
Do not discriminate colors
Highly sensitive to light (active in dark)
Cones
Photoreceptors. Modified epithelial cells.
Provide color vision and acuity
Densely clustered in macula
Especially in fovea centralis
Bipolar cells in Eye
Synapse with rods and cones 1st order neurons
Ganglion cells in Eye
Synapse with bipolar cells 2nd order neurons
Explain photoreception
Absorption of a photon changes retinal from 11 cis to 11-trans form which activates the opsin
Opsin activates transducin (G-protein)
Which activates phosphodiesterrase (PDE)
PDE reduces levels of cyclic GMP
Chemically gated sodium ion channels close
Dark Current is reduced
Rate of neurotransmitter release declines
Rods
Detect presence or absence of photons
Cones
Provide information about wavelengths of photons
Both rods and cones have
inner segment containing major organelles
outer segment with membranous discs contains visual pigments
Describe the process of photoreceptor recovery after simulation
Bleaching - After absorbing a photon
Rhodopsin splits into retinal and opsin
11-trans retinal is converted back to 11-cis retinal
Requires ATP
Retinal then recombines with opsin
Describe the different neurons involved in a general sensory pathway
First-order neuron - sensory neuron that delivers sensation to cns
Second-order neuron - interneuron in spinal cord or brainstem that receives information from first order neuron
Crosses to opposite sied of CNS decussation
Third-Order Neuron - Neruon in thalamus that must receive information from second-order neuron
Function - Spinothalamic Pathway
Carries sensations of crude touch, pressure, pain, and temperature
First-order neurons enter spinal cord and synapse within posterior horns
Second-order neurons cross to opposite side of spinal cord before ascending
Third-order neurons in thalamus
Abnormalities - Spinothalamic Pathway
Phantom Limb Syndrome - Painful sensations that are not produced where they are perceived to originate
Referred Pain - Feeling pain in an uninjured part of body when pain originates at another location. Visceral pain can manifest as pain in body surface
Function - Dorsal Column Pathway
Carries sensations of fine touch, vibration, pressure, and proprioception
First-Order neuron enter and synapse of second-order neurons in the posterior columns
Second-order neurons decussate
Synapse with third-order neurons in the thalamus
Function - Spinocerebellar
Conveys information about positions of muscle, tendons, and joints from spinal cord to cerebellum
This information does not reach our awareness
visceral sensory pathways
Cranial nerves V, VII, IX, and X
Spinal Nerves T1-L2 and S2-S4
Solitary nucleus
Large nucleus on each side of medulla oblongata
Major processing and sorting center for visceral sensory information
Extensive connections with cardiovascular and respiratory centers and reticular formation
Auditory Pathway
Afferent fibers of sensory neurons in spiral ganglion form cochlear nerve
Axons enter medulla oblongata and synapse at cochlear nucleus
information ascends to pons and midbrain
midbrain coordinates unconscious motor responses
Ascending auditory sensations synapse in the thalamus
projection fingers deliver information to auditory cortex of temporal lobe
Central Processing - Visual Information
Axons from ganglion cells converge on optic disc
Proceed toward diencephalon as optic nerve (II)
two optic nerves reach diencephalon after partial crossover at optic chiasm
Information travel to visual cortex in occipital lobe
information travels to the suprachiasmatic nucleus of the hypothalamus
Field of Vision
The combined visual images from left and right eyes
Depth Perception
obtained by comparing relative positions of objects between images received from both eyes
Explain why image formation on the retina upside down and left-right reversed
The light form the top of the object ends up lower retina surface.
light doesn’t arrive in eye directly
Prefrontal Areas - Executive functions
includes working memory and attention
Primary motor cortex
Precentral gyrus
motor homunculus
functional map of primary motor cortex
Corresponds with specific regions of the body
indicates the degree of fine motor control available
major neurons of the somatic motor pathways
Upper motor neuron
Lower motor neuron - innervates a single motor unit in a skeletal muscle
Function - Corticospinal Pathway
Provides voluntary control over skeletal muscles
Structure - Corticospinal Pathway
Begins at primary motor cortex
Axons descend into brainstem and spinal cord
Synapses on lower motor neurons that control skeletal muscles
Reflex
Rapid, Automatic responses to specific stimuli
Basic building blocks of neural function
A specific reflex produces the same motor response each time
List the different components of a reflex arc
Sensory receptor
Sensory neuron
information processing in CNS
motor neuron
Effector
Innate Reflexes
Basic neural reflexes formed before birth
genetically programmed
Withdrawal, Chewing, Visual Tracking
Acquired reflexes
Rapid, automatic learned motor patterns
repetition enhances them
Breaking a car in an emergency.
Monosynaptic Reflex
Sensory neuron synapses directly with motor neuron, fast response
Polysynaptic Reflex
At least one interneuron between sensory neuron and motor neuron; most common
Slower response; delta increase with number of synapses involved
List the steps in a stretch reflex (using the patellar reflex as an example)
Monosynaptic
Regulates skeletal muscle length throughout the body
very rapid
Patellar Reflex - Kick your leg when struck
1 stimulus = muscle stretching
2 distortion of receptor sends action potential through sensory neurons
3 sensory neuron synapses with motor neurons in spinal cord
4 motor neurons send signals to motor units; triggers reflexive contraction of stretched muscle
withdrawal reflexes (with an example)
Move body part away from stimulus (pain or pressure)
Strength and extent of response depends on intensity and location of stimulus
Touch a hot pan remove hand from hot pan
reciprocal inhibition
For flexor reflex to work, stretch reflex of antagonistic (extensor) Muscles must be inhibited (reciprocal inhibition) by interneurons in spinal cord.
crossed extensor reflex (with an example)
Coordinated with flexor reflex. Step on something sharp, before flexor reflex can lift injured foot, crossed extensor reflex straightens opposite limb to receive body weight, then flexor reflex can occur. maintained by reverberating circuits
Sympathetic division
Fight or flight. Increases alertness, metabolic rate, and muscular abilities
Parasympathetic division
Rest and digest. Conserves energy and maintains resting metabolic rate
Increased Sympathetic Activity Body Reactions
- Heightened mental alertness
- Increased metabolic rate
- reduced digestive and urinary functions
- activation of energy reserves
- increased respiratory rate and dilation of respiratory passageways
- increased heart rate and blood pressure
- activation of sweat glands
Increased Parasympathetic Activity Body Reactions
- Decreased metabolic rate
- decreased heart rate and blood pressure
- increased secretion by salivary and digestive glands
- increased motility and blood flow in digestive tract
- stimulation of urination and defecation
Anatomy of the Sympathetic Division
Short preganglionic fingers, in the thoracic and lumbar segments of spinal cord
Preganglionic (Central) neurons located between segments T1 and L2
Cell bodies in lateral horns and azons exit through anterior roots.
Ganglionic neurons in ganglia near spinal cord
long postganglionic fibers to target organs
Sympathetic chain ganglia
On either side of vertebral column. One preganglionic fiber synapses on many ganglionic neurons. Fibers interconnect sympathetic chain ganglia, making the chain look like a string of pearls. Each ganglion innervates a particular body organ or group of organs. Superior cervical and paravertebral ganglia if target superior or inferior to segment the preganglionic fiber emerges from
Splanchnic nerves
Do not synapse in the chain ganglia.
Fibers continue as the greater or lesser splanchnic nerves
Synapse in collateral ganglia
Collateral ganglia
Anterior to vertebral bodies
Contain ganglionic neurons that innervate abdominopelvic tissues and viscera
Celiac ganglion
Superior mesenteric ganglion
Inferior mesenteric ganglion
Adrenal medullae
Center of each adrenal gland
Modified sympathetic ganglion
when stimulated, they release neurotransmitters into blood stream
Anatomy of the Parasympathetic Division
Long preganglionic fibers in brainstem and sacral segments of spinal cord (S2-S4)
Ganglionic neurons in peripheral ganglia within or adjacent to target organs
short postganglionic fingers in or near target organs
Terminal ganglia and Intramural ganglia
List the cranial nerves that have parasympathetic functions and what those functions are
Parasympathetic preganglionic fibers leave brain in cranial nerves
II (Oculomotor)
VII (Facial)
IX (glossopharyngeal)
X (vagus) - Provides 75 percent of all parasympathetic outflow
Describe the cholinergic system including locations of nicotinic cholinergic and muscarinic cholinergic receptors
Preganglionic fibers release acetylcholine
Ganglionic neurons have cholinergic receptors: Nicotinic and Muscarinic
Nicotinic cholinergic receptors are ligand-gated ion channels
Stimulated by nicotine
Muscarinic cholinergic receptors are G protein-coupled receptors
stimulated by muscarine
Describe the adrenergic system
Adrenergic system
Preganglionic fibers release norepinephrine or epinephrine
alpha-1
More common type
found primarily in smooth muscle cells
stimulation has excitatory effect
alpha-2 - probably not on test
Found of preganglionic sympathetic neurons
Stimulation has an inhibitory effect
Coordinates activities of ANS
beta-1
Located on membrane of cells in skeletal muscles, lungs, heart, liver, etc.
Stimulation increases metabolic activity
beta-2
Located on membrane of cells in skeletal muscles, lungs, heart, liver, etc.
Stimulation triggers relaxation of smooth muscles along respiratory tract
beta-3
Located on membrane of cells in skeletal muscles, lungs, heart, liver, etc.
stimulation leads to lipolysis
Explain why many visceral senses do not reach conscious perception
When a third-order neuron is not involved or thalamus does not allow the stimulation to enter the brain. Baroreceptors that monitor blood volume and blood pressure
Describe referred pain
Visceral pain that is perceived to be superficial pain
When you have a heart attack your left arm hurts is an example
Kidney stone you say lower back hurts not kidney
Short reflexes
Completely peripheral
Autonomic reflexes
Vagus nerve response to stretch of the stomach
Long reflexes
Include the CNS
Somatic reflexes
Autonomic reflexes
Describe dual innervation with examples
Most vital organs are innervated by both divisions of ANS
Two divisions commonly have opposing effects
Parasympathetic postganglionic fibers travel by cranial nerves to peripheral destinations
Sympathetic innervation reaches same structures
Control of Heart rate is an example
Control of Heart rate is an example of Dual Innervation. Elaborate
Muscarinic cholinergic receptors - Parasympathetic division - Lowers heart rate
Beta 1-adrenergic receptors - Sympathetic division- Increase heart rate
Control of Pupillary Diameter is an example of Dual Innervation. Elaborate
Muscarinic Cholinergic receptors located on circular fingers of the iris- Parasympathetic division- Pupillary Constriction
Alpha-adrenergic receptors located on the radial fibers of the iris- Sympathetic division- Pupillary dilation
Sympathetic control of blood vessel diameter
NE is released from sympathetic fibers at smooth muscles cells in blood vessel walls
Increasing or decreasing the rate of action potential firing changes the diameter of the blood vessel
Describe autonomic tone
Resting level activity of ANS
Because nerves maintain background level of activity the can increase or decrease activity
provides greater range of control
Significan where dual innervation occurs
More important where it does not occur
Hypothalamus - Integration
Regulates autonomic and endocrine function
In the pupillary light reflexes triggers either a sympathetic (not enough light) or parasympathetic (too much light) response
Two tracts that connect hypothalamus with major parasympathetic nuclei in the brain stem and preganglionic neurons of the thoracolumbar spinal cord
Amygdala
Group of nuclei in the limbic lobe of the temporal lobe
Emotional Responses
Memory
Strong connection with the hypothalamus
Fell afraid signal the hypothalamus to trigger a sympathetic response (fight or flight)
Medulla Oblongata
Cardiovascular center
Cardiac acceleratory center - Increase heart rate
Cardiac inhibitory center - Decrease heart rate
Sympathomimetic Drugs
Mimic the effects of the sympathetic division
Phenylephrine - Alpha-1 Adrenergic agonist
Used to dilate bronchioles and often paired with other drugs
for asthma
used to dilate pupils
pseudoephedrine
Sympatholytic Drugs
Interfere with sympathetic function
Beta-Blockers commonly used to treat cardiovascular disease such as high blood pressure - Propranolol
Alpha-Agonist used to treat hypertension and anxiety - Clonidine
Parasympathomimetic
Mimic the effects of the parasympathetic division, increase parasympathetic tone
Nicotine, Muscarine,
Pilocarpine - Nonspecific muscarinic agonist
Constricts Pupil
Can be used after an eye exam or for treatment of glaucoma
Parasympatholytic
Antagonistic to parasympathetic division, decrease parasympathetic tone
Atropine - dilates pupils
Muscarinic antagonist
Scopolamine - motion sickness
Muscarinic antagonist
