Physiology Exam 3

general senses

touch, temperature, pain, itch, proprioception
no specialized sensory organs; receptors distributed throughout body

special senses

vision, taste, hearing, smell, equilibrium
specialized sensory organs and receptors

simple receptor

neurons with free nerve endings; may have myelinated or unmyelinated axons
ex. pain receptors on skin (nociceptors)

Complex receptor

nerve endings enclosed in connective tissue capsules with myelinated axon
ex. pacinian corpuscle (touch)

nonneural receptor

special sense receptors are cells that release neurotransmitter onto sensory neurons initiating an action potential
ex. hair cell (hearing)

stretch receptors

proprioception
mechanically gated channels in muscle spindles

what type of receptors do olfaction and gustation use?

chemoreceptors

olfactory pathway to the brain

pathways from the olfactory bulb lead to the amygdala and hippocampus causing smells to be connected with memories

taste sensations that use second messenger systems

sweet, bitter, and umami are transducted via G-protein coupled receptor second messenger systems
cascade set off by the system amplifies the signal

taste sensations that use direct channels

salty and sour are communicated through ion channels

Why do taste receptor cells have tight junctions?

preventing the flow of saliva into the taste bud itself

external eye anatomy function

protection of the eye
control the diameter of the pupil
absorb light
direct light rays towards fovea

pathway of light to photoreceptor

light reflected off objects
enters cornea
pupil
lens
vitreous humor
arrives at retina

human blind spot

axons exit from the retina via optic nerve
optic nerve is a space without photoreceptors

Myopia

trouble focusing distance (nearsighted)
overly elongated eyeball

Hyperopia

trouble focusing on near objects (farsighted)
too short of an eyeball

Presbyobia

degenerative loss of ability to focus on near objects
thickening and loss of flexability of lens, less elastic ciliary muscles

Astigmatism

blurred vision caused by extra curvy cornea
multiple focal points

Rods

black and white
detect at low light levels (seeing at night)
found on outer edges of retina

Cones

color vision; 3 types in humans (red, blue, green)
high light levels
concentrated in the fovea

The sensory system does all of the following EXCEPT...

projects nerves and signals to effect change in target muscles

Sensory system does the following:

encode information from the environment
relay information about the environment to the CNS
detect change in the environment

Which of these is NOT a characteristic of olfaction?

Olfaction is one of the three senses contributing to our sense of equilibrium.

Characteristics of olfaction

Neurons from the olfactory bulb interact with the amygdala and hippocampus.
Olfactory neurons die and are replaced by new neurons roughly every 2 months.
The olfactory tracts do not directly relay to the CNS via the thalamus.

The taste receptor cells are NOT neurons.

true

The lens bends light and focuses it onto the...

fovea

The primary sensory neurons in your retina are depolarized, the concentration of cyclicGMP in your rods is high, and cyclic-nucleotide gated channels are open. It is likely..

night time

Which of these is most likely an example of top-down processing in the visual system?

an optical illusion

The inner ear houses two fluid filled structures. Which of these is critical to equilibrium?

the semicircular canals

What features are shared (or similar) between hearing and vision?

pathways from paired sensory organs diverge and cross over on the way to the CNS
information is relayed thru the thalamus
they both involve some type of tonic receptor

Motor neurons typically control multiple muscles cells.

True

In skeletal muscle cells, incoming electrical signals travel through the...

T-tubules

The structural elements responsible for the striated appearance of skeletal muscle are called...

sarcomeres

The calcium pumps (Ca2+ ATPase) in the sarcoplasmic reticulum are examples of...

active transport

The muscle twitch (i.e. the contraction-relaxation cycle) is much faster than an action potential

false

Release of acetylcholine at the neuromuscular junction typically results in...

opening of chemically-gated sodium channels.
opening of voltage-gated sodium channels.
release of calcium ions (Ca2+) from the sarcoplasmic reticulum.

Increasing muscle mass thru exercise is primarily due to...

increasing the thickness of existing muscle fibers.

An olympic sprinter will tend to have more thicker muscle fibers relying on glycolytic metabolism.

True

Smooth muscle is under voluntary control.

False

Reflex arcs are an exception to the rule that skeletal muscle is always under voluntary control.

True

During voluntary movement, you change your body posture….

before you move in anticipation of the movement AND after initiating the movement to compensate or correct your body’s position.

Phototransduction in rods

the process by which the absorbed light triggers an electrical response (the neural signal) in rods and cones
the conversion of light into a change in the electrical potential across the cell membrane

What differentiates ON vs. OFF bipolar cells?

ON-center bipolar cells are depolarized by small spot stimuli positioned in the receptive field center. OFF-center bipolar cells are hyperpolarized by the same stimuli

What are some basic properties which contribute to visual processing?

color, brightness, color and brightness contrasts (for form perception and visual acuity), visual field representation, binocular fusion and depth perception.

What are “visual fields”?

the total area in which objects can be seen in the side (peripheral) vision as you focus your eyes on a central point.

top-down processing

interpretation of incoming information based on prior knowledge, experiences, and expectations
(ex. optical illusion)

bottom-up processing

retrieval of sensory information from our external environment to build perceptions based on the current input of sensory information

A person with defective rods will have trouble

distinguishing shapes at the periphery of the visual field
seeing well in the dark

A blind spot in the retina occurs where

the optic nerve leaves the eye

iris

controls diameter of the pupil

Rhodopsin

light receptor

tectorial membrane

stimulates hair cells

cristae in ampullae

senses rotational movement
movement causes cupula to move activating hair cells

otoliths in maculae

senses lateral movement
crystals in ear move with head movement

The primary purpose of the middle ear bony structures (maleus, incus, and stapes) is to

amplify the vibration as it conducts to the cochlea

You work at the Tabasco factory in Louisiana. You spend your workday blending barrels of fermented chili peppers with vinegar and bottling hot sauce. The smells do not bother you, because...

olfactory receptors are phasic, they quickly adapt to constant stimulus

skeletal muscle contraction starts when the muscle fiber depolarizes due to the release of calcium into the cytoplasm

False
starts at the neuromuscular junction

Why does rigor mortis occur after death?

Myosin is tightly bound to actin
there is no ATP available to bind to myosin (cannot enter relaxation phase)

Which is a potential energy source for an athlete sprinting the 40-yard dash?

phosphocreatine

which about smooth muscle are true

Ca2+ initiates the contraction
smooth muscle uses actin-myosin crossbridges to create force
Contraction can occur without a change in membrane potential

As a protective mechanism, stretching a skeletal muscle fiber causes sensory neurons (i.e. proprioceptors) to ______ their rate of firing.

increase

outer ear function

collects sound waves and channels them into the ear canal (external auditory meatus), where the sound is amplified

middle ear function

to efficiently transfer acoustic energy from compression waves in air to fluid–membrane waves within the cochlea.

Inner ear function

transform the vibrations into electrical impulses that then travel along the eighth cranial nerve (auditory nerve) to the brain

What type of receptor is the inner ear hair cell?

mechanoreceptors

What is one important reason that auditory information from the left and right ears “crosses
over” on its way to the auditory cortexes?

Allows for the determination of localization of sound

Sensorineural Hearing Loss

hearing loss due to failure of the inner ear or auditory nerve

conductive hearing loss

hearing loss due to problems with the bones of the middle ear or the outer ear (earwax)

central Hearing Loss

nerve or brain damage

What type of receptors are used for the sense of equilibrium?

mechanical proprioreceptors

somatic nervous system

controls voluntary movement

somatic neural pathway

Originates in the CNS – in brain or ventral horn of spinal cord
Myelinated, very long, always excitatory
Terminal braches close to target and each terminal innervates a single skeletal muscle fiber (target)

Skeletal muscle

a muscle that is connected at either or both ends to a bone and so move parts of the skeleton
mostly under voluntary control

Cardiac muscle

the muscle tissue of the heart; adapted to continued rhythmic contraction
cells joined together by junctions

smooth muscle

small and lack striation

flexor-extensor pairs

antagonistic muscle group
flexors bring bones together and extensors move bones apart

muscle fiber

a muscle cell