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Physiology Exam 2 Review 2-28-17
Mad dog and Jonah
Special Senses Review
What do you need to focus on?
Type of Hormone ( Behavior)
Regulation/Stimulation of these hormones
Duration in Blood
Amino acid based
Constructed from amino acids, peptides in RER
Packaged in vesicles
Exocytosis of vesicles
Constructed from Cholesterol in SER
Blood transport proteins
Inside the cell
Have you made your hormone chart yet?
Make your own, writing it out is the best way of learning it
Know general overview and divisions of nervous system (ex. Branches of nervous system, nerve cell types)
Know the different types of neurotransmitters and their effects (excitatory vs. inhibitory)
Walk yourself through the entire process of a nerve impulse (also relevant going into the muscular system)
Break down each individual sense and go over pathway (ex. Walk through phototransduction with eye, secondary chemical messenger with smell, etc.)
Structure of The Eye
Layers of the eye
Fibrous outer layer
Vascular middle layer
Retina (inner) layer
-phagocytize photoreceptor cell fragments
-Contain the three cells required for sight:
2. Bipolar Cells
3. Ganglion cells
Three Layers of Inner Pigment
Photoreceptors- Responsible for sensing light (phototransduction)
Bipolar Cells – Responsible for integrating stimulus (Perception)
Ganglion Cells- Responsible for sending signal to optic nerve and to the brain
Inner layer of the retina
Light moves from Photoreceptors bipolar cells ganglion cells
Cis Rhodopsin/Retinal Trans-Rhodopsin Active Transducin (G protein) Activates Phosphodiesterase
Cyclic GMP is responsible for maintaining open Sodium Channels
If we no longer have sodium channels open, what happens to the membrane potential? Does this release neurotransmitter or inhibit neurotransmitter release? Which neurotransmitter?
In the dark
Photoreceptors are CONSTANTLY DEPOLARIZING and releasing glutamate
In the light
Closing of the Na+, Ca2+ channels causes them to HYPERPOLARIZE! No longer releasing glutamate
Responsible for integrating (perceiving) stimulus
Glutamate behaves differently based on the type of receptors (pathway) it acts on
This is where we get the light ON/Light OFF pathways from
Light ON/Light Off Pathway
Stimulus: end result of phototransduction:
Hyperpolarization causes a decrease in the amount of glutamate released onto bipolar cells
Decreased amount of glutamate released onto bipolar cells
In the Light-ON pathway, glutamate is considered inhibitory
By decreasing the level of N.T. that would normally inhibit a process, we are inhibiting the inhibitor
Depolarizes the bipolar cell
Increases release of N.T. into ganglion cells
Ganglion cells will generate more action potentials
In the Light-OFF pathway, glutamate is considered excitatory
1. By decreasing the level of N.T. that would normally excite a process, we are preventing excitation
2. Hyperpolarizes the bipolar cells
3. Decreases the release of N.T.’s on ganglion cells
4. Ganglion cells generate less action potentials
Generate the action potentials that are later sent to the brain for further interpretation
Types of taste buds have different pathways
Salty- Ion channel
Sour- Ion channel
Sweet- G-Protein (Gustducin)
Bitter- G-protein (Gustducin)
Umami- G-protein (Gustducin)
With sound, we care about the Cochlea
Within the cochlea we have the scala vestibule, cochlear duct (full of endolymph which contains a high K+ concentration), and the scala tympani
Within the cochlear duct, we have the organ of corti
Organ of Corti
The receptor cells of the organ of corti are called hair cells they have hair-like stereocilia
We have 1 row of inner hair cells responsible for transducing the pressure waves caused by fluid movement into receptor potentials
We have 3 rows of outer hair cells embedded in tectorial membrane
The tectorial membrane overlies the organ of Corti
Stays stationary when hairs are bent due to incoming sound
Mechanical process (we are mechanically moving stereocilia)
The direction that the stereocilia move will determine N.T. release
If stereocilia bend towards the tallest member of the bundle….
“Tip links” pull open mechanically-gated cation channels
Opens V-G Ca+2 channels
Increase N.T. release (glutamate)
If stereocilia bend away from the tallest member of the bundle….
“Tip links” slacken
Close K+ channels/never activate V-G Ca+2 channels
Inhibit N.T. release (glutamate)
Sensed in the vestibular apparatus
Vestibular apparatus consists of:
Detects angular rotation
Semicircular canals contain stereocilia
Stereocilia are encapsulated in a gelatinous mass (cupula) which extends to the ampulla (slight bulge in the wall of each duct)
At rest, the cupula is upright
During rotational acceleration, the endolymph flow bends the cupula and causes depolarization
The speed/magnitude of rotational head movements determines the direction that the stereocilia are bent and which hair cells are stimulated. This will determine the change in membrane potential/neurotransmitter release
Work together to sense linear acceleration of the head, and changes in head position (brain will only be informed of changing positions of the head)
Respond to mechanical stimulation of moving hairs
In every bundle of hairs, there is one hair that is the tallest (kinocilium)
Utricle: hair cells point straight up
Saccule: hair cells point laterally
Stereocilia and kinocilia are covered in a gelatinous substance that contains otoliths (tiny stones). These otoliths make the gelatinous fluid heavier so that it can really move the hair cells upon stimulation
When hair cells bend towards the kinocilium:
Hair cell depolarizes
Excites the nerve fiber
Generates more frequent action potentials
When hair cells bend away from the kinocilium:
Hair cell hyperpolarizes
Inhibits the nerve fiber
Decreases action potential frequency
A secreted substance that activates a receptor on the cell that secreted it is an example of_______.
_______ involves secretion of a substance onto the receptor of a different, nearby cell.
One of the least complicated of the endocrine control systems directly responds to changing blood levels of ions and nutrients. Which of the following describes this mechanism?
Type 2 diabetes often have insulin at adequate levels in the bloodstream. What other component of this endocrine signaling pathway could be broken?
Steroid hormones make use of _______
Secondary chemical messenger systems
An extracellular receptor has been damaged. Which of the following hormone receptors may have been affected?
Which of the following is TRUE regarding oxytocin
Its regulation is an example of a positive feedback control mechanism
It is an anterior pituitary hormone
Its most important effect occurs during menstruation
It controls milk production
The major targets of growth hormone are ________
The blood vessels
The adrenal glands
Bones and skeletal muscle
Which of the following hormones regulate inorganic ion composition of the body______.
Thyroxine, Parathyroid hormone, Cortisol
Calcitonin, Parathyroid Hormone, Cortisol
Calcitonin, Parathyroid Hormone, Aldosterone
Calcitonin, Ocytocin, Aldosterone
Growth hormone has a(n) _____ receptor and affects blood glucose levels similar to ______.
Cell Surface, Glucagon
Cell Surface, Insulin
What hormone is used to raise blood pressure by retaining Na+?
Which hormones might you inject into a patient to promote Ca2+ uptake by bones in order to treat weak bones (osteoporosis)?
Release of epinephrine from the adrenal medulla is under direct control of ________.
The nervous system
Which of the following increases blood glucose in response to a stressful event?
Insulin modulates blood glucose through_______.
Increasing ATP Production
Patients suffering diabetes insipidus or diabetes mellitus both have ______.
Glucose in their urine
A and B
Which of the following hormones is NOTtransported bound to plasma proteins?
Which of the following hormones is NO Ttransported bound to plasma proteins?
All of the following hormones have intracellular receptors EXCEPT _____.
Iodine deficiency causes an overgrown thyroid gland (goiter) due to _____.
Failure of a negative feedback loop
Failure of a positive feedback loop
Overuse of a negative feedback loop
Overuse of a positive feedback loop
Thyroid hormones (T3 and T4) are unique with respect to other endocrine hormones. Which of the following is true?
They are the only steroid hormones stored outside of cells
They regulate their levels through a positive feedback mechanism
They do not require signaling through a secondary chemical messenger
None of the above
T3, T4 Synthesis
TSH from anterior pituitary stimulates follicular cells to produce thyroglobulin
Thyroglobulin is produced via ER/Golgi and exocytosed into colloid
Iodide is absorbed from blood via secondary active transport
Iodide travels across cell and enters colloid via facilitated diffusion
Iodide is oxidized to iodine and attached to tyrosine A.A.s on thyroglobulin
The iodinated tyrosines are linked together to form T3, T4
This T3,T4-thyroglobulin complex is endocytosed by follicular cells
This endosome is joined with a lysosome
Enzymes in lysosome cleave T3,T4 from thyroglobulin
T3,T4 enter bloodstream
Thyroglobulin is recycled
Low blood Ca2+ will most likely ____ parathyroid hormone and _____ calcitonin.
Normal development of the immune response is due in part to hormones produced by the ______.
The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on ______.
The location of the tissue or organ with respect to the circulatory path
The membrane potential of the cells of the target organ
The presence of the appropriate receptors on the cells of the target tissue or organ
Which of the following hormones modify blood glucose levels?
Growth hormone, Cortisol
All of the above
Which of the following is not a change typically produced by a hormonal stimulus?
Activates or deactivates enzymes
Stimulates production of an action potential
Alters plasma membrane permeability
Induces secretory activity
Would you like us to go over impulse transmission?
Review- Impulse Transmission
Dendrites receive signal from previous neuron (Neurotransmitters through Ligand gated Channels)
Summation (Temporal or Spatial) of Excitatory/Inhibitory Postsynaptic Potential causes a Graded Potential
Summation either reaches threshold potential or it doesn’t (All or none)
Once threshold potential is reached, triggers Action Potential at axon hillock
Voltage Gated Sodium and Potassium channels are opened (Remember that potassium channels are delayed and do not function right away
Sodium rushes inside the cell and causes a depolarization of the axonal membrane, depolarization triggers channels down the line to open (propagation down the cell membrane)
(After depolarization down the line) Sodium channels close following depolarization, Potassium channels begin working and potassium flows out causing repolarization
Overshoots resting membrane potential causing hyperpolarization, triggering the cell to reestablish the membrane potential
During repolarization: Refractory period (To ensure propagation is only one way)
Absolute Refractory period (No matter how much stimulus received, cannot begin another Action Potential)
Relative Refractory period (Action potential can be triggered but it requires more stimulus than normal)
Sodium Potassium Pumps reestablish concentration gradient (Active transport as opposed to facilitated during the propagation)
Review-Neuronal Synaptic Transmission
Once depolarization reaches axon terminal, Calcium channels activate during depolarization
2. Calcium rushes into cell and binds to calcium binding sites on vesicles containing neurotransmitters.
3. Binding causes changing in conformation and binding sites attach to cis and trans snares on membrane lining the synapse
4. Snares pull vesicles to cell membrane; vesicles fuse with membrane and release neurotransmitter into synapse
5. Neurotransmitters in synapse received by ligand-gated channels on the next axon’s dendrites (Or on the target organ/cell)
6. Entire process begins again.
Multiple sclerosis affects _____ of the Central Nervous system by interfering with_____
Oligodentrocytes, Graded potentials
Oligodentrocytes, Action Potentials
Schwann cells, Graded potentials
Schwann Cells, Action potentials
On neurons, ligand gated channels are found on _____ while voltage gated channels are found only on _____.
Dendrites and axons, axons
Axons and cell bodies, dendrites
Dendrites and cell bodies, axons
Equilibrium potentials for ions are not dependent on _____.
Charge of the ion
Permeability of the membrane for the ion
The electrical difference across cell membranes is generated by _____.
Potassium Leak channels
The NA/KATPase pump
A drug that causes the neuronal plasma membrane to become more permeable to Na+ would ______ the resting membrane potential
Which of the following properties is not characteristic of neurons?
Capable of mitotic division
High metabolic rate
Which of the following correctly describes a graded potential?
Long distance signaling
Can be excitatory or inhibitory
Requires a voltage stimulus to initiate
Immediately after an action potential has reached its most positive value, which channels open?
What glial cell type in the central nervous system (CNS) helps to control the extracellular K+ concentration around neurons?
What glial cell type in the PNS is responsible for myelin?
______ is most frequently used to signal motor output by the peripheral nervous system.
A natural toxin works by blocking glycine receptors. Postsynaptic cells exposed to this toxin should show _____ postsynaptic potentials
The period after an initial stimulus when a neuron is not sensitive to another stimulus is the ______.
Relative refractory period
Absolute refractory period
Which of the following neurons has the fastest action potential?
Small diameter neuron with myelin
Large diameter neuron with myelin
Small diameter neuron without myelin
Large diameter neuron without myelin
Would you like us to go through the process again?
Ordinarily, it is not possible to transplant tissues from one person to another, yet cornease can be transplanted with very low rates of tissue rejection. This is because the cornea _____.
Is not a living tissue
Has no nerve supply
Has no blood supply
Does not contain connective tissue
Light passes through the following structures in which order?
Vitreous humor, lens, aqueous humor, cornea
Cornea, aqueous humor, lens, vitreous humor
Cornea, vitreous humor, lens, aqueous humor
Aqueous humor, cornea, lens, vitreous humor
Which of the following is the category of diseases which can lead to a buildup of pressure within the eye and lead to optic nerve damage and blindness?
Which of the following is stimulated by light in the photoreceptor?
Opening of channels permeable to Na and Ca
Conversion of GMP to cyclic GMP
Activation of PDE
Photoreceptor membrane depolarization
Glutamate is an important neurotransmitter in sensory systems where it can _______ postsynaptic cells
Depolarize and hyperpolarize
Only work through a G-protein
Select the correct statement about hearing
Hair cells are located in the scala vestibule
Hair cell depolarization involves G-protein signaling
Hair cells closest to the oval window sense high frequency sound waves
Damage to the hair cells is a form of conduction deafness
Which of the following is TRUE about taste receptors?
In order for a chemical to be sensed, it must be hydrophobic
There are over 100 different chemical receptors for taste
They do not adapt to flavors
Depolarization occurs through G-protein dependent and independent mechanisms
The sensory cells in this structure are sensitive to high frequency mechanical deformation
An inhibitor of G-protein signaling would not influence this taste sensation
Which of the following types of neurons are replaced (regenerated) throughout adult life?
Olfactory sensory neurons
Retinal bipolar cells
Retinal ganglion cells
Auditory inner hair cells
Which of the following systems does not make use of G-protein signaling
Sense of Hearing
Secondary chemical messenger system
Sense of smell
Sense of Hear