Chapter 12 - Hormones Flashcards
What do the Senses do?
Maintain homeostasis, by providing information about the
outside world and the internal environment
What are the 2 types of senses?
General and Special
General Senses
- Receptors that are widely distributed throughout the body
- Skin, various organs, and joints
Special Senses
- Specialized receptors confined to structures in the head
- Eyes, ears, nose, and mouth
What are Sensory Receptors
- Collect information from the environment, and relay it to the CNS on
sensory neurons - Link nervous system to internal and external changes or events
- Can be specialized cells or multicellular structures
Sensory receptors facts
- Respond to specific stimuli
- Particularly sensitive to a certain type of environmental
change, and less sensitive to other stimuli - Allow body to interpret sensory events
What are the 5 types of sensory receptors in the body?
- Chemoreceptors
- Pain receptors (nociceptors):
- Thermoreceptors
- Mechanoreceptors
- Photoreceptors
what are Chemoreceptors
- Respond to changes in chemical concentrations
- Smell, taste, oxygen concentration
what are Pain receptors (nociceptors):
- Respond to tissue damage
- Mechanical, electrical, thermal energy
what are Thermoreceptors
- Respond to moderate changes in temperature
what are Mechanoreceptors
- Respond to mechanical forces that distort receptor
- Touch, tension, blood pressure, stretch
what are Photoreceptors
- respond to light
- eyes
Sensation facts
- Occurs when action potentials make the brain aware of a
sensory event - Example: Awareness of pain
Perception facts
- Occurs when brain interprets sensory impulses
- Example: Realizing that pain is a result of stepping on a tack
Projection facts
- Process in which cerebral cortex interprets sensation as being
derived from certain receptors - Brain projects the sensation back to the apparent source
- It allows a person to locate the region of stimulation
Sensory Adaptation:
- Ability to ignore unimportant (or continuous) stimuli
- Involves a decreased response to a particular stimulus
from the receptors (peripheral adaptation) or along the
CNS pathways leading to the cerebral cortex (central
adaptation) - When sensory adaptation occurs, sensory impulses
become less frequent and may cease - Stronger stimulus is then required to trigger impulses
- Best accomplished by thermoreceptors and olfactory
receptors
What are General Senses?
- Senses with small, widespread sensory receptors, associated
with skin, muscles, joints, and viscera
- General Senses are divided into what 3 groups:
- Exteroceptive
- Interoceptive (visceroceptive)
- Proprioceptive
Exteroceptive senses
- Senses associated with body surface
- Examples: Touch, pressure, temperature, and pain
Interoceptive (visceroceptive) senses
- Senses associated with changes in the viscera
- Examples: Blood pressure stretching blood vessels
Proprioceptive senses
- Senses associated with changes in muscles, tendons, and joints, body
position - Examples: Stimulated when changing position or exercising
What are the 3 types of mechanoreceptors that respond to touch and pressure?
- Free nerve endings
- Tactile (Meissner’s) corpuscles
- Lamellated (Pacinian) corpuscles
Free nerve endings
- Common in epithelial tissues
- Simplest receptors
- Sense itching and other sensations
- Tactile (Meissner’s) corpuscles:
- Abundant in hairless portions of skin and lips
- Detect fine touch and texture
- Distinguish between 2 points
- Lamellated (Pacinian) corpuscles:
- Nerve endings encased in large ellipsoidal structures
- Common in deeper subcutaneous tissues, tendons, and ligaments
- Detect heavy pressure and vibrations
Temperature receptors (thermoreceptors):
- Free nerve endings in skin
what are the 2 types of thermoreceptors?
- Warm receptors
- Cold receptors
Warm receptors
- Sensitive to temperatures above 25°C (77°F)
- Unresponsive to temperature above 45°C (113°F)
Cold receptors
- Sensitive to temperatures between 10°
(50°F) and 20°C (68°F)
Pain receptors
- Respond to temperatures below 10°C; produce freezing sensation
- Respond to temperatures above 45°C; produce burning sensation
Pain receptors/nociceptors facts
- Consist of free nerve endings
- Widely distributed
- Nervous tissue of brain lacks pain receptors
- Stimulated by tissue damage, chemicals, mechanical
forces, or extremes in temperature, oxygen deficiency - Adapt very little, if at all
Visceral Pain is…?
- Pain receptors are the only receptors in viscera whose
stimulation produces sensations - Pain receptors in viscera respond differently to stimulation
than those of surface tissues
Visceral pain may feel as if coming from some other part of
the body; this is called…?
Referred Pain
Example of referred pain…?
Heart pain often feels like it is
coming from the left shoulder or medial portion of left arm
Referred pain results from ______ _____ ________, in which sensory impulses from the visceral organ and a certain area of the skin synapse with the same neuron in the CNS
Common Nerve Pathways
Thalamus
begins sensation of pain
Cerebral Cortex
- Judges intensity of pain
- Locates source of pain
- Produces emotional and motor responses to pain
- The emotional response to pain involves the limbic system
Gray matter in brainstem
- Regulates flow of impulses from spinal cord
Pain-inhibiting substances produced in the body are…?
- Enkephalins
- Serotonin
- Endorphins
Proprioceptors
Mechanoreceptors that send information to CNS about body
position, and length and tension of skeletal muscles
What are the 3 main types of proprioceptors?
- Lamellated (Pacinian) corpuscles:
- Muscle spindles:
- Golgi tendon organs:
- Lamellated (Pacinian) corpuscles:
- Pressure receptors in joints
- Muscle spindles:
- Stretch receptors in skeletal muscles
- Initiate stretch reflexes, in which spindle stretch causes muscle
contraction
- Golgi tendon organs:
- Stretch receptors in tendons
- Stimulate reflexes that oppose stretch reflexes
- Help maintain posture, and protects muscle attachments from being
pulled loose
Visceral senses:
- Have receptors in internal organs
- Examples: Lamellated corpuscles, free nerve endings
- Convey information that includes the sense of fullness
after eating a meal as well as the discomfort of intestinal
gas and the pain that signals a heart attack
Special Senses
- Senses that have sensory receptors are within large,
complex sensory organs in the head
What are the types of special senses and their organs?
- Smell: Olfactory organs in nasal cavity
- Taste: Taste buds in oral cavity
- Hearing and equilibrium: Inner ears
- Sight: Eyes
Olfaction
the sense of smell
- Olfactory receptors:
- Olfactory receptor cells are chemoreceptors
- Respond to chemicals dissolved in liquids
- Sense of smell provides 75 to 80% of sense of taste
Olfactory organs
- Contain olfactory receptor cells (bipolar neurons) and supporting epithelial
cells - Olfactory neurons have knobs at the distal ends of their dendrites covered
with cilia - Cover upper parts of nasal cavity, superior nasal conchae, and a portion of
the nasal septum - Odorants may bind to any of almost 400 types of olfactory membrane
receptors, resulting in depolarization and action potentials
Olfactory Pathways
- Once olfactory receptors are stimulated, nerve impulses
travel through openings in cribriform plates of ethmoid
bone - Olfactory nerves → olfactory bulbs → olfactory tracts →
limbic system (for emotions) and olfactory cortex (for
interpretation) - Olfactory bulbs process sensory impulses
- Limbic system, center for memory and emotion, provides
emotional responses to certain odorant molecules
Gustation
sense of taste
Taste buds
- Organs of taste
- Located on papillae of tongue, roof of mouth, linings of cheeks, and walls of
pharynx - About 10,000 taste buds, each with 50 to 150 taste cells
taste receptors
- Chemoreceptors
- Taste cells: modified epithelial cells that function as receptors
- Taste hairs: microvilli that protrude from taste cells through pores of taste
buds; sensitive parts of taste cells - Taste cells are replaced every 3 days
What are the 5 Primary Taste Sensations?
- Sweet: Stimulated by carbohydrates
- Sour: Stimulated by acids (H+
) - Salty: Stimulated by salts (Na+ or K+
) - Bitter: Stimulated by many organic compounds, Mg and Ca
salts - Umami: Stimulated by some amino acids, MSG
Taste Sensations
- Each flavor results from 1 primary taste sensation or a
combination - Spicy foods may stimulate a class of pain receptors
- Taste receptors undergo rapid adaptation
Ear
organ of hearing and equilibrium
what are the 3 sections of the ear?
- outer/external ear
- middle ear
- inner/internal ear
What are the Parts of the Outer Ear?
T.E.A.
- Auricle (pinna)
- External acoustic meatus
- tympanic membrane (eardrum)
Auricle (pinna)
- funnel-shaped
- collects sounds waves
external acoustic meatus
- S-shaped tube
- Lined with ceruminous glands
- Carries sound to tympanic membrane
- Terminates at tympanic membrane
- Tympanic membrane (Eardrum):
vibrates in response to sound waves
What are the 3 parts of the Middle Ear
- tympanic cavity
- auditory ossicles
- oval window
Tympanic cavity
air-filled space in temporal bone
Auditory ossicles
- 3 tiny bones
- Vibrate in response to tympanic membrane vibrations; amplify force
- Malleus, incus, and stapes (hammer, anvil, and stirrup)
Oval Window
- Opening in wall of tympanic cavity
- Stapes vibrates against it to move fluids in inner ear
Auditory (eustachian) tube:
- Connects middle ear to throat
- Helps maintain equal air pressure on both sides of
tympanic membrane - Usually closed by valve-like flaps in throat
Inner ear is a complex system of _________?
Labyrinth
- Osseous (bony) labyrinth:
- Bony canal in temporal bone
- Filled with fluid called perilymph
- Membranous labyrinth:
- Tube of similar shape that lies within osseous labyrinth
- Filled with fluid called endolymph
what are the Three portions of labyrinths?
- Cochlea functions in hearing
- Semicircular canals function in dynamic equilibrium
- Vestibule functions in static equilibrium
There are 2 membrane-covered “windows” in the wall of the bony labyrinth which are?
- Oval window:
-Opening in the wall of the tympanic cavity, through which the stapes
transfers vibrations to the fluid of the inner ear
-Vibrations stimulate hearing receptors - Round window:
-Window in the wall of the inner ear facing the tympanic cavity
-Dissipates excess vibrations into the tympanic cavity
Cochlea
- Spiral, snail-shaped tube, widest at its base, becomes narrower
toward tip - Coiled around bony core, the modiolus
- Spiral lamina is a bony shelf that coils around cochlea
Auditory Pathways are (from top to bottom)
cochlear branch of vestibulocochlear nerve > medulla oblongate > midbrain > thalamus > auditory in temporal lobe of cerebrum
Feeling of equilibrium/balance is derived from what 2 senses?
static equilibrium
&
dynamic equilibrium
Static Equilibrium
- Senses position of head when body is not moving
- Receptors are found in vestibule of inner ear
Dynamic Equilibrium
- Senses rotation and movement of head and body
- Receptors are found in semicircular canals
Visual receptors are found in the…?
Eye
Accessory organs for sense of sight
- Upper and lower eyelids (palpebrae, protection)
- Eyelashes (protection)
- Lacrimal apparatus (tear production)
- Extrinsic eye muscles (eye movement)
Eyelids (Palpebrae):
is composed of what 4 layers?
- Skin: Thinnest in body
- Muscle: Orbicularis oculi closes eyelid, Levator palpebrae
superioris muscle opens it - Connective tissue: Contains tarsal glands, which secrete oil onto
eyelashes - Conjunctiva: Mucous membrane that lines eyelid and covers
portion of eyeball
Conjunctiva
Mucous membrane that lines eyelid and covers
portion of eyeball
What makes up the Lacrimal Apparatus?
- lacrimial gland
- canaliculi
- lacrimal sac
- nasolacrimal duct
- lysozyme
Lacrimal gland
- in orbit, lateral to eye
- secretes tears
canaliculi
- 2 ducts that collect tears
lacrimal sac
- collects tears from canaliculi
- lies in groove in lacrimal bone
nasolacrimal duct
- collects from lacrimal sac
- empties tears into nasal cavity
lysozyme
- antibacterial component of tears
what are the Six Extrinsic Eye Muscles for eye movement and their functions?
- Superior rectus:
- Rotates eye up and media
- Inferior rectus:
- Rotates eye down and medially
- Medial rectus:
- Rotates eye medially
- Lateral rectus:
- Rotates eye laterally
- Superior oblique:
- Rotates eye down and laterally
- Inferior oblique:
- Rotates eye up and laterally
The eye:
Hollow, sperical organ of sight
the wall of eye has 3 layers which are?
- Outer (fibrous) tunic
- Middle (vascular) tunic
- Inner (nervous) tunic
Outer (fibrous) tunic:
- Consists of cornea and sclera
- Portions of outer tunic:
Cornea
- Anterior one-sixth
- Transparent window of eye
- Helps focus light rays
- Transmits and refracts light
Sclera
- Posterior five sixths
- White, opaque, tough
- Protects eye, attaches muscles
- Pierced by optic nerve and blood vessels
Middle (vascular) tunic:
- Consists of choroid coat , ciliary body, iris
- Portions of middle tunic
Choroid coat:
- Posterior five-sixths
- Provides blood supply
- Contains melanocytes; melanin absorbs extra light
Ciliary Body
- Anterior portion
- Thickest portion, pigmented
- Forms ring to hold lens; changes lens shape for focusing
- Contains ciliary muscles to move lens, and radiating folds (processes)
Iris
- Anterior to ciliary body, in front of lens
- Pigmented
- Controls light entering eye
Anterior cavity of eye:
- Cavity between cornea and lens
- Filled with a watery fluid, aqueous humor
Lens
- Transparent, biconvex, lies behind iris, elastic
- Held in place by suspensory ligaments of ciliary body
- Helps focus light ray
Accommodation
- A change in the shape of the lens, to view close objects
- Lens thickens and becomes more convex when focusing on close object
- Lens thins and becomes flatter when focusing on distant objects
- The ciliary muscle relaxes the suspensory ligaments during
accommodation
The Iris facts
- Controls amount of light entering the eye
- Consists of connective tissue and smooth muscle (colored portion of
eye) - Pupil is window or opening in center of iris
- Dim light stimulates radial muscles and pupil dilates
- Bright light stimulates circular muscles and pupil constricts
- Amount and distribution of melanin determines eye color
the Pupil is…?
the window or opening in center of iris
Aqueous Humor:
- Fluid in anterior cavity of eye
- Fills both anterior and posterior chambers of anterior cavity; circulates
through pupil - Secreted by epithelium on inner surface of the ciliary body
- Provides nutrients and maintains shape of anterior portion of eye
- Leaves cavity through scleral venous sinus
Posterior cavity
- Space enclosed by lens, ciliary body, and retina
- Contains vitreous humor
- Vitreous body: Vitreous body + collagen fibers
Vitreous humor
thick gel that holds retina flat
against choroid coat, and helps maintain the shape of the
eye
Inner tunic consists of retina:
- Retina contains visual receptors (photoreceptors)
- Continuous with optic nerve in back of eye
- Ends just behind margin of the ciliary body toward front of eye
- Macula lutea: yellowish spot in retina
- Fovea centralis: center of macula lutea; produces sharpest vision
- Optic disc: blind spot; contains no photoreceptors; found where nerve
fibers from retina leave eye to become optic nerve
Macula Lutea
yellowish spot in retina
Fovea Centralis
center of macula lutea, produces sharpest vision
Optic disc
blind spot; contains no photoreceptors; found where nerve
fibers from retina leave eye to become optic nerve
Photoreceptors are
modified neurons of retina that sense light:
the inner tunic consists of retina is composed of several layers
- From innermost layer, they are photoreceptor cells, horizontal cells, bipolar cells,
amacrine cells, and ganglion cells - Photoreceptor cells, bipolar cells, and ganglion cells provide pathway for impulses
triggered by photoreceptors to reach the optic nerve - Horizontal cells and amacrine cells modify, integrate impulses
Photoreceptors are composed of…?
rods and cones
Rods
- Long, thin projections (rod-shaped)
- Contain light sensitive pigment, called rhodopsin
- Hundreds of times more sensitive to light than cones
- Provide vision in dim light
- Produce vision without color in shades of gray
- Produce outlines of objectsC
Cones
- Short, blunt projections (cone-shaped)
- Contain light sensitive pigments, called erythrolabe, chlorolabe, and cyanolabe
- Provide vision in bright light
- Produce sharp images
- Produce color vision
- Fovea centralis contains only cones
rods and cones contain…?
light-sensitive pigments that decompose upon light absorption
Rhodopsin (Visual purple, light-sensitive pigment in discs of
rods)
- In presence of light, decomposes into Opsin and Retinal
- Triggers a complex series of reactions that initiates nerve impulses
- Impulses travel along optic nerve
- Iodopsins (light-sensitive pigments in discs of cones):
- Each type of cone contains different light-sensitive pigment
- Each type of cone is sensitive to different wavelengths
- Color perceived depends on which types of cones are stimulated
- Erythrolabe: responds to red light
- Chlorolabe: responds to green light
- Cyanolabe: responds to blue light
Erythrolabe
responds to red light
Chlorolabe
responds to green light
Cyanolabe
responds to blue light
Stereoscopic Vision
- Provides perception of distance, depth, height, and width of objects
- Possible because of distance between pupils
- Results from formation of two slightly different retinal images from
eyes - Overlapping images from the two eyes combine in visual cortex to
form a single 3-dimensional image of object
Age-related hearing loss due to:
- Damage to hair cells in spiral organ
- Degeneration of neural pathways to the brain
- Tinnitus
Age-related visual problems include:
- Dry eyes
- Floaters (crystals in vitreous humor)
- Loss of elasticity of lens, decreasing accommodation (presbyopia)
- Glaucoma
- Cataracts
- Macular degeneration
Age-related smell and taste problems due to:
- Loss of olfactory receptors (anosmia)
