Physiology exam 4

What is the law of specific nerve energies (sensory receptors)

Sensory receptors can only process specific signals

What is sensory transduction?

It is converting stimuli into a receptor potential (action potential for a sensory receptor) 

What are the two subtypes for sensory receptors?

Direct and indirect 

What is an example of direct?

Olfactory neurons, their dendrites come into contact with the external environment 

What is the general structure of a sensory neuron?

Axon terminals in central nervous system, axon, cell body, and sensory receptors with endings in the peripherary

Explain how it can be hard when one neuron is covering a large receptive field

When a neuron covers when whole receptive field it is harder to distinguish the stimuli seperately

What is lateral inhibition?

It occurs when neighboring neurons inhibit each other, so the neuron closest to the stimulus fires more strongly while those further away are suppressed. Removes excess neural activity (think of strong hand pressing on arm example)

What is a first order neuron?

detects the stimulus directly from the receptor and sends it to the spinal cord or brainstem

What is a second order neuron?

It receives the signal from the first order neuron in the spinal cord or brain stem then sends the signal to the thalamus

What are the three receptor classes for skin?

Mechanoreceptors, thermoreceptors, and nocireceptors

What are mechanoreceptors?

Physical stimuli

What are thermoreceptors?

warm and cold

What are nocireceptors?

based off of pain

Where are warm thermorecptors in the skin?

Deep within the dermis

Where are cold thermoreceptors located?

These are located closer to the epidermis (which is closer to the top skin layer)

What is accomodation? and how does lens shape change based on far and close

It is changing the lens shape of your eye depending on object distance.

How does accomodation play role in a far object?

• cillary muscle is relaxed

• lens → flatter

• no parasympathetic involvement

What is the role of accommodation in a near object?

• ciliary muscles constrict

• lens → more spherical

• parasympathetic involvement

What is the name for a normal accomadating eye?

Emmetropia

What is myopia?

• near sidedness

• unable to accomadate for far objects so you get close sided accomadation but far obejcts are going to be very blurry

What is hyperopia?

• far sidedness

• your eyes are able to be stretched and flattened and can see far, but cannot be rounded so you cannot see up close

When you have pupillary constriction what part of autonomic nervous system is activated?

Parasympathetic

When you have pupillary dilation what part of autonomic nervous system is activated?

Sympathetic

Which direction do our photoreceptors face in our eye, why?

They face to back of our eyes and this is unknown could possibly be to protect photoreceptors 

If you where to zoom into a rod, what is significant you would find?

Rhodopsin

What does rhodopsin do?

It is a membrane protein that processes light, and determines whether light and dark or color

what light you see in cones vs rods?

light/dark rods and color for cones

What happens when rhodopsin molecules are activated?

They will cause specific kind of ion influx:

if this is in the dark: there will be an influx of sodium and efflux of potassium and then influx of calcium causing more exocytosis to the bipolar neuron

if in the light: no sodium will enter rod and there will be an efflux of potassium causing hyperpolarization and calcium channels closed and decreased exocytosis to bipolar neuron

What are three main structures of the middle ear?

• tympanic membrane

• ossicles

• oval window

What is the ossicle comprised of?

• malleus

• incus

• stapes

What are structures that are part of your inner ear? (within one another)

• cochlea

  • helicotrema

    • basilar membrane

      • organ of cort

What is importance of stapes?

flows into oval window

What is the function of the organ of corti?

It is the combination of membranes, within it has endolymph (fluid), and sensory hair cells

When sound waves come in, what happens in organ of corti?

Sound wave will come in and transfer into endolymph and then cause hair cells to move

What is sensory transduction hearing?

It is the bending of hair cells which cause changes in action potentials

What are the main ions in sensory transduction hearing?

Potassium and calcium 

When you hear a very loud sound what does this do to your hair cells?

More bending

How does ear distinguish pitch?

frequency and location

If there are lots of vibrations in the beginning coming in the ear at the start of the helicotrema how would you process that pitch?

low pitch

What are the structures in the vastibular aparatus?

Semicircular canals

• endolymph

• hair cells

Utricle/saccule

What part of sensory does vestibular apparatus function in?

equilibrium

What do your semicircular canals helps with?

How endolymph moves when your head rotates, so they detect rotational and angular movement 

What is function of utricle/saccule?

• oversee linear accleration (forward→back, up→down)

• gelatinous layer that oversees hair cells

• otoliths: layer of calcium crystals that sits on gelatinous layer 

• functionality same as semicircular canals 

What part of ear is involved in vertigo?

related to otoliths layer being destructed

What do cerebellum, cortex, sensory systems, eye movements relate back to?

Vestibular nuclei

What kind of receptors are taste and smell overseen by?

Chemoreceptors

What is gustation?

Taste related and refers to responses to chemicals from foods

What is olfaction?

Smell related to chemicals in the air

General pathway of chemical going through taste receptor

The tastant binds to receptors on the microvilli, activating the taste receptor cell, which then sends signal to sensory neuron (taste afferent) that carries information to the brain

What are taste pores?

Regions of the tongue that allows fluids to enter and come into contact with gustatory receptors 

What happens when taste receptors are triggered by a tastant?

They create a receptor action potential

Where does perception of taste information flow after the receptors are activated?

Into the cortical gustatory area of the brain, as well as the hypothalamus and limbic system

Can you damage your taste buds?

Receptors are renewed every 10 or so days 

What are the five main taste modalities?

Salt, sour, sweet, bitter, and umami (savory)