Chapter 41: The Sensory System

The role of sensory system

Organisms use sensory system to communicate and interact with the external environment, to respond to changes from external and internal environments, receives and processes information that generates an individual's awareness of their environment.

The two types of sensory systems

General senses and special senses

General senses

Receptors spread throughout the body: Temperature, pain, pressure, vibration, proprioception. Respond to frequency of the arriving action potentials.

What is the basis of somatic sensation?

Tactile receptors

Tactile receptors

Merkel’s corpuscles, Pacinian or lamellated corpuscles, Ruffini’s corpuscles, Meissner’s corpuscles

Baroreceptors

Detects pressure changes

Where do baroreceptors detect blood pressure?

Carotid sinus, aortic sinus

Proprioceptors

Maintain equilibrium, sense position in joints and skeletal muscles

What two things maintain equilibrium?

Muscle spindles and Golgi tendon organs

Name the three middle ear bones in the order they are arranged?

Malleus, Incus, Stapes (MIS)

What is the name of structure A (Ear Diagram)?

Auditory Canal

What is the name of structure B (Ear Diagram)?

Auditory Nerve

What is the name of structure C (Ear Diagram)?

Ear drum or Tympanic membrane

What is in contact with the oval window?

The base plate of the stapes

Inner ear or internal ear

Contains cochlea and vestibular apparatus

Semicircular canals

Sense rotational motion; contain expanded regions called ampulla

Utricle and saccule

Sense forward and vertical acceleration

Cochlea contains how many chambers?

Scala vestibuli, scala media (also called the cochlear duct), and scala tympan

Vestibular canal

Contains perilymph

Cochlear canal

Contains endolymph

Photoreceptors

Rods and cones

Rods structure

Outer segment and inner segment

Outer segment contains what?

Pigment-containing discs

Rods have visual pigment called?

Rhodopsin

Rhodopsin contains what two things?

Opsin and retinal

11-cis retinal converts to?

All-trans retinal

What are the three primary colors of cones?

Red, blue, and green

Photoreceptor cells synapse with?

Bipolar cells or bipolar neurons

Bipolar cells synapse with?

Ganglion cells

Sensory fibers form the?

Optic nerve

Chemoreception

Chemosensory neurons detect chemicals that sense chemicals in the air, saliva, or blood; Need aqueous medium (mucous)

Olfaction

Smell – olfactory receptors in olfactory neurons in the nose detect the presence of odorants

Where are olfactory organs present?

Olfactory epithelium

Gustation

Taste – taste receptors in taste buds respond to dissolved chemicals

Certain chemicals present in hot peppers such as capsaicin also release?

Heat

What is the function of the different types of receptor proteins?

Mechanoreceptors- detect mechanical (physical) forces, Photoreceptors- detect light, Chemoreceptors- detect specific molecules or chemical conditions, Thermoreceptors- detect the flow of heat energy.

Name structure A (Eye diagram).

Lens

What is the function of structure B (Eye diagram)?

Permits light to enter the eye (Pupil)

Name the fluid that fills structure C (Eye diagram).

Vitreous humor or vitreous body (Posterior chamber)

Name the type of photoreceptor cells concentrated in structure D (Eye diagram)

Cones (Fovea centralis, region of acute vision)

Name structure E (Eye diagram).

Optic nerve

Name structure F (Eye diagram).

Cornea

Rods provide information on what? Cones provide information on what?

Rods provide information on the presence of photons and cones provide information on the wavelength of photons (aka color)

Which configuration of retinal is its active form?

The 11-trans form

What is the photopigment in rods?

Rhodopsin

When is the retinal of rhodopsin active?

Active when there’s light

Place these terms in order of the visual pathway: optic nerve, retina, optic chiasm, primary visual cortex, lens, LGN (lateral geniculate nucleus)

Lens -> retina -> optic nerve -> optic chiasm -> LGN (lateral geniculate nucleus) ->primary visual cortex

The left eye’s image is transmitted to which half of the hemisphere?

Right hemisphere

Fibers cross at the?

Optic chiasm

True or False: The three photopsins are red, yellow, and blue cones

False - the three cones are RGB -> red, green, and blue cones

The _______ ________ contains olfactory glands that produce mucus

Olfactory epithelium

What receptors do migrating sea turtles use to navigate?

Magnetoreceptors

True or False: An eel using electric fields in the environment to detect prey is a form of active electroreception.

False - prey detection is passive

What 3 types of receptor proteins do nociceptors use?

Mechanosceptors, thermal receptors, chemo receptor protein

General senses describes our sensitivity to what?

Temperature, pain, touch, pressure, vibration, and proprioception (body position)

Light passes through the _______ and _______ and is focused on the _______

Cornea, pupil, retina

What is Sensory transduction?

Change in the language from the mechanical form of energy into the electrical or electrochemical form of energy

Mechanoreceptors detect what?

Detect any kind of mechanical energy

What do cats communicate through?

Body languages, vocalization, scents

What do bats use to sense direction?

Echolocation

What is activated when sympathetic nervous system is activated?

Heightened awareness of the sensory information

What are the four basic taste?

Sweet, sour, salt and bitter

Where do bipolar neurons synapse?

Ganglion cells

Olfactory sensation is also known as?

Olfaction

Taste sensation is also known as?

Gustation

What are taste buds embedded in?

Lingual papillae

What do Beluga whales use?

Magneto receptor that senses change in magnetic field for means of communication

What are nociceptors?

Pain sensors

What are some natural painkillers?

Endorphins and Enkephalins

What are the hearing organs located?

In the cochlea

What is the primary function of the Pina?

To protect the opening of the external ear canal or the auditory canal

Name a structure in the inner ear that contain equilibrium?

Vestibular apparatus

What three things does the visual pathway have?

Lens, retina, optic nerve

True or false: Thermoreceptors are not important for snakes sensing prey.

False; They are important for snakes to sense prey

How is the lens suspended?

Suspensory ligaments

What is the opening at the front of the eye?

Pupil

What are the muscles responsible for accommodation?

Ciliary muscles

What is the outer layer of the eye?

Fibrous tunic

What is the middle layer of the eye?

Choroid

What is the inner layer of the eye?

Retina

What is the space between the cornea and lens filled with?

Aqueous humor

Where are cones concentrated?

Fovea centralis

What kind of light are rods sensitive to?

Dim light

What kind of receptors to mosquitoes have?

Thermal receptors

What animal contains pit organs (facial openings that allow for sensing of infrared radiation and "see" in the dark)?

Rattlesnakes

Define the term "stimulus"

Any change in the external or internal environment that is detected by the body

Tactile corpuscles/ merkel corpuscles

Responsible for the light touch sensation

Ruffini nerve endings

Responsible for detecting deep pressure and also responsible for detecting the amount of roughness of the surface

Laminated corpuscles/pacinian corpuscles

Responsible for detecting deep pressure and vibration as well

Free nerve endings

Responsible for detecting very light touch

Pinna function

To protect the opening of the external ear canal or the auditory canal

Name some structures of the external ear.

The helix, the anti-helix, the fossa triangularis, the conquer, the lobule

Organ of Corti

Organ of hearing

The process whereby you detect the stimulus okay and then the stimulus is converted in the form of electrochemical potential and then which is then transduced into the into the central nervous system. This entire process is known as what?

Sensory transduction

What does the ear drum convert soundwaves into?

Vibration form of energy

Where does the tympanic membrane end?

At the external ear

Where are hearing organs located?

Located in the cochlea

What are the main structural differences between rods and cones?

Cones are responsible for color and bright vision, while rods are specialized for dim vision

What is the macula?

A small, highly sensitive area in the center of the retina, the light-sensitive layer at the back of the eye

Where does the light pass to get into the eye?

Cornea to pupil to lens