Lab Practical 2 Definitions

How to orient an eye?

How to orient an eye?

1. Cornea egg shaped (when squeezing eye)

   • The pointer side is lateral side

   • the blunter side is medial side

2. Extra Ocular muscles: find inferior rectus and oblique (superior oblique always cut off)

   • Rectus muscles go straight down, up, left or right when pulled on

   • Oblique muscles go diagonal when pulled on

   • Inferior oblique connects to lateral aspect of eye and medially to the skull by the nose

What is special about the nictitating membrane?

Seen in non-human animals and not in humans

List the cranial Nerves in order

1. Ooh, Ooh, Ooh, to touch and feel very good velvet. Such heaven!

   O: olfactory nerve (CN I)

   O: optic nerve (CN II)

   O: oculomotor nerve (CN III)

   T: trochlear nerve (CN IV)

   T: trigeminal nerve(CN V)

   A: abducens nerve (CN VI)

   F: facial nerve (CN VII)

   V: vestibulocochlear nerve (CN VIII)

   G: glossopharyngeal nerve (CN IX)

   V: vagus nerve (CN X)

   S: spinal accessory nerve (CN XI)

   H: hypoglossal nerve (CN XII)

process by which information about the environmental stimuli is received by a sensory receptor and then converted to action potentials that are sent to the brain

Sensation

the brain receiving and interpreting the action potentials such that we are consciously aware of the sensation

Perception

What is this an example of: a thermoreceptor will respond to a change in temperature at the skin surface and produce an action potential

sensation

What is this an example of: After the temperature change causing an action potential that information is then sent to the brain, which will receive and interpret the information as hot or cold

perception

Sensory receptor that responds to stimuli from the external world.

exteroceptor

Sensory receptor in the viscera that is sensitive to changes and stimuli within the body’s internal environment; also called visceroceptor

interoceptor

a sensory receptor that responds to mechanical stimuli such as touch, pressure, and vibration

Mechanoreceptor

a sensory receptor found in muscle, joint, and tendon tissue that detects changes in body position or movement

Proprioceptors

a sensory receptor that responds to changes in temperature

Thermoreceptors

a sensory receptor that detects light or changes in light, found only in the eyes

Photoreceptors

a sensory receptor that responds to chemicals in solution

Chemoreceptor

a sensory receptor that responds to stimuli that is harmful to the body

Nociceptors

Sensory receptors can be categorized by:

• Location

• Type of stimuli they respond to

Sensory receptor location categorizes

1. exteroceptor

2. interceptor

Sensory receptor type of stimuli categorizes

1. Mechanoreceptor

2. Proprioceptors

3. Thermoreceptors

4. Photoreceptors

5. Chemoreceptor

6. Nociceptors

The body can respond to some stimuli in a rapid, predictable pattern

Reflex Arcs

Components of Reflex Arcs

1. receptor

2. integration center

3. effector organ

A cell or nerve ending of a sensory neuron specialized to respond to particular types of stimuli

receptor

respond to a particular type of sensory stimulus and then creates an action potential which is sent to the integration center

receptor

interpret the incoming information (from receptor) and send out a motor response

integration center

The process by which the nervous system processes and interprets sensory input and makes decisions about what should be done at each moment.

Integration

Muscle or gland (or other organ) capable of being activated by nerve endings and carries out motor response

effector organ

Sent out by integration center to effector organ in response to stimulus

motor response

require no experience or “learning” to be carried out by the body

intrinsic

Intrinsic reflex that are associated with very rapid movement of skeletal muscle tissue

spinal reflex arc

Reflex responsible for moving your hand after touching a hot stove

spinal reflex arc

1. Pupillary Reflex

2. Accommodation Reflex

Eye Reflexes

open space at the center of the iris, the colored portion of the eye, that allows light to enter the eye and strike the retina

pupil

What is the iris’ function

controlling how much light enters the eye

how does iris control how much light enters the eye

The iris has two types of muscles that will control the diameter of the pupil, therefore controlling how much light enters the eye

when this muscle of the iris contracts, it causes the pupil to become wider

dilator pupillae muscle

when this muscle of the iris contracts, it causes the pupil to become narrower

sphincter pupillae muscle

the stimulus is applied to only one side of the body, but the response (or output) is observed on both sides of the body

consensual reflex

a structure inside the eye that helps to focus light directly on the retina by bending light as it enters the eye, allowing for clear vision

lens

the size of the pupil changes according to distance of object requiring focus to adjust the amount of light entering the eye

Pupil accommodation

the lens can change shape to change the ability to refract light to focus it on the retina

Lens accommodation

to bend a light ray

refract

the ability of a substance to bend light or the ability of the eye to focus light

refractory power

Correlation of lens shape and refractory power

The more round the lens (or the more it bulges), the stronger the refractory power. The flatter the lens, the less refractory power

Eyes reaction: If a person is looking at an object that is close

light from the object will be highly scattered as it enters the eye. The lens accommodates this with a higher refractory power to bend light, so it is less scattered when it hits the retina

Eyes reaction: When looking at an object farther away

light from the object is less scattered as it enters the eye. The lens does not have to refract light as much and is therefore flatter

depending on the distance of the object we look at, the eyes may need to
converge, which is the process of both eyes moving (or pointing) inward to focus on an object. This action requires the use to medial and lateral rectus muscles of the eyes

Convergence

which is the process of both eyes moving (or pointing) inward to focus on an object

converge

any reflex arc that occurs when a tendon is tapped. This causes a rapid and predictable contraction of the muscle associated with the tendon

Tendon (Stretch) Reflexes

This reflex occurs when the patellar tendon just below to patella (or kneecap) is stretched when it is tapped by a reflex hammer.

knee-jerk reflex (patellar reflex)

What does knee-jerk reflex assess?

L2-L4 level of the spinal cord

This maneuver alters the patellar reflex by forcing the individual to focus their attention somewhere else in the body, rather than thinking about the patellar reflex being performed on them

Jendrassik’s maneuver

when the Achilles tendon on the back of the ankle is tapped

ankle-jerk reflex (achilles reflex)

What does ankle-jerk reflex assess?

the S1 nerve root

The knee-jerk reflex and ankle-jerk reflex arcs also involve the relaxation of what muscle

antagonistic muscle

The general rule with a muscle and its antagonist is

that when the muscle contracts, the antagonist lengthens (and vice versa).

examine by touch

Palpate

a response mediated by the sympathetic nervous system (the “fight or flight” response) in response to pain

ciliospinal reflex

a reflex the protects the sole of the foot when a painful stimulus is applied at the sole. This reflex is most easily observed at the toes, which move in response to the stimulus, plantar flexion

Plantar Reflex

abnormal reflex the when a painful stimulus is applied at the sole. This reflex is most easily observed at the toes, which move in response to the stimulus in dorsiflexion

Babinski’s reflex

Babinski’s reflex indicates

• normal in child under 1

• abnormal in everyone else

• an be observed in individuals with amyotropic lateral sclerosis (LouGehrig’s disease), multiple sclerosis, stroke, and severe spinal cord injuries

movement in which toes bend (or curl) downward

plantar flexion

movement in which toes bend (or curl) upward (seen in big toe most)

dorsiflexion

Proprioception and Spatial Orientation and Nystagmus are both part of the equilibrium reflex

Labyrinthine Reflexes

three fluid-filled tubes in the inner ear

semicircular canals

function of semicircular canals

contribute to balance and equilibrium while moving by aiding in visual fixation on moving objects

When stimulated, the semicircular canals cause a reflexive movement of the eyes called

nystagmus

stimulated by forward and backward head movements

anterior semicircular canal

stimulated by movement causing the head to tilt to the side

posterior semicircular

stimulated by movement where the head spins or moves side-side

lateral semicircular canal

The reflexive eye movement that is characteristic of nystagmus has 2 phases:

1. fast phase nystagmus

2. slow phase nystagmus

The direction of nystagmus is designated as that of the

fast phase

if a person is angularly accelerated in one direction, their eyes will move __ in one direction _ as though to maintain fixation on a moving target, then _ move or twitch in the opposite direction _

if a person is angularly accelerated in one direction, their eyes will move slowly in one direction (slow phase) as though to maintain fixation on a moving target, then very rapidly move or twitch in the opposite direction (fast phase)

rotary movement of the eye that can be observed during movement when the fluid in the semicircular canal moves (or flows), stimulating receptors in the inner ear

Rotary nystagmus

where the eyes continue to move reflexively after movement has stopped

post-rotary nystagmus

the fast phase and slow phase of post-rotary nystagmus is _ that of rotary nystagmus

the fast phase and slow phase of post-rotary nystagmus is opposite that of rotary nystagmus

the ability to maintain the body’s position and posture in relation to our surroundings.

Spatial orientation

The brain can carry out spatial orientation function by receiving information from a what structures

1. inner ear

2. proprioceptors

3. photoreceptors

receptors here respond to changes in head position during linear acceleration and rotational movement

The inner ear

this sensory receptor monitors information such as joint position and stretch,
joint angles, tendon tension, and muscle stretch. This information concerning the position and movement of our body parts allows the brain to produce smooth, coordinated body movements without needing to visually monitor the movement

Proprioceptors

receptors in the eyes provide visual information to the brain. This allows the brain to understand how body parts are positioned relative to one another and the body and to be aware of our external environment (objects that surround us, etc)

Photoreceptors

List the “Five Senses”

1. taste

2. vision

3. hearing

4. smell

5. touch

Tactile sensibility

Touch

The sensory receptor class responsible for the sensation of touch

mechanoreceptor

mechanoreceptor is stimulated by

stimulated by the physical deformation of the receptor

relationship between receptive area and sensitivity to touch

The smaller the receptive area the more sensitive the skin will be to touch

the smallest distance at which two points of contact can be felt

two-point threshold

If a stimulus is applied for a prolonged period without change, the rate of receptor discharge will slow, and conscious awareness of the stimulus will decline or is lost (until some stimulus change occurs)

sensory adaptation

auditory processing

hearing

hearing loss that results from damage to structures from the tympanic membrane to the auditory ossicles (malleus, incus, and stapes)

Conduction deafness

Hearing loss that occurs when the auditory nerve or brain is damaged

Nerve deafness

Conduction deafness prevents

prevents transmission of sound to the inner ear.

Nerve deafness causes

action potentials relating to sound are either not produced by the auditory nerve or cannot be interpreted by the brain

sensing with the eyes

Vision

the closest point at which an object can be placed from the face and still form a focused image within the eye’s accommodation range

near point

demonstrate the elasticity of the lens and its ability to accommodate when viewing an object up close

The near point test

we age, the lens becomes

less flexible and the accommodation becomes less effective

loss of near focusing ability

age related

presbyopia

area at the back of the eye on the retina where there are no photoreceptors for visual reception.

Optic Disc (blind spot)

the sharpness of vision, involving the ability to discern letters or numbers at a given
distance according to a fixed standard

Visual acuity

Easy test of visual acuity

Snellen Test

uses a chart with letters of different sizes. The overall idea here is
that for a “normal” eye (i.e., an eye with normal vision), letters of different sizes should be seen clearly at different distances. Larger letters should be seen at longer distances, and smaller letters should be seen at shorter distances

Snell Test