Chapter 12 - Special Senses Flashcards
(43 cards)
1
Q
Senses
A
maintain homeostasis by providing information about the outside world and environment
2
Q
2 Categories of Senses
A
- General: receptors widely distributed throughout the body
○ e.g. skin, various organs, joints- Special: specialized receptors confined to structures in the head
○ E.g. ears, nose, mouth
- Special: specialized receptors confined to structures in the head
3
Q
Pathway of Sensory Information
A
- The stimulus stimulates sensory receptors
- Transduction occurs where the stimulus is converted into receptor potentials
- Transmission occurs where the receptor potentials trigger action potentials and are conducted along sensory neurons to the CNS
- Interpretation occurs in the CNS
4
Q
5 Types of Sensory Receptors
A
- Chemoreceptors: respond to changes in chemical concentrations
○ E.g. smell, taste, oxygen concentration- Pain(nociceptors) receptors: respond to tissue damage
- Thermoreceptors: respond to moderate changes in temperature
- Mechanoreceptors: respond to mechanical forces distorting receptors
○ E.g. touch, stretch, tension - Photoreceptors: respond to light
5
Q
Sensation V Perception
A
Sensation: when action potentials make the brain aware of an event
- Awareness of pain
Perception: when the brain interprets sensory impulses
- e.g. realizing pain is due to stepping on a tack
6
Q
Sensory Projection
A
when the cerebral cortex interprets sensation as being derived/originating from certain receptors
- Allows a person to locate the region of stimulation due to feeling it at that location
7
Q
Sensory Adaptation
A
is done to help ignore unimportant or continuous stimuli leading to stronger stimuli required to trigger impulses
- Best done by thermo or olfactory receptors
8
Q
Types of General Senses
A
- Exteroceptive Senses: senses associated with body surface like touch, pressure, temperature and pain
- Interoceptive senses: senses associated with changes in the viscera like BP stretching blood vessels
- Proprioceptive senses: associated with changes in muscles, tendons and joints
- Interoceptive senses: senses associated with changes in the viscera like BP stretching blood vessels
9
Q
Types of Mechanoreceptors
A
- Free nerve endings: common in epithelial tissues and sense itching
- Tactile corpuscles: detect fine touch and texture and help distinguish between 2 points
- Lamellated corpuscles: detect heavy pressure and vibrations
10
Q
Thermoreceptors
A
free nerve endings in the skin
- Warm receptors are sensitive to temperatures above 77F
- Cold receptors are sensitive to temperatures between 50-60F
11
Q
Pain Receptors(Nociceptors)
A
- Consist of free nerve endings and are widely distributed
- No adaptation
12
Q
Referred pain
A
visceral pain that can be felt in different areas of the body due to common nerve pathways
13
Q
Pain Pathways
A
- Fast Pain: myelinated fibers which conduct impulses rapidly and stop as soon as the stimulus stops
- Slow pain: unmyelinated which conduct impulses slowly and often create aching pain even after the stimulus stops
14
Q
Types of Proprioceptors
A
- Lamellated corpuscles: detect pressure in joints
- Muscle spindles: stretch receptors in skeletal muscles and initiate stretch reflexes
- Golgi tendon organs: stretch receptors in tendons that oppose stretch reflexes and help maintain posture
- Muscle spindles: stretch receptors in skeletal muscles and initiate stretch reflexes
15
Q
Visceral Senses
A
lamellated corpuscles and free nerve endings which convey information such as feelings of fullness after a meal or discomfort of intestinal gas
16
Q
Synesthesia
A
where the brain interprets a stimulus for one sense as coming from another
- e.g. the paint smelled blue
Can be caused by genetic mutations/TBI
17
Q
Olfactory Nerves
A
- Olfactory receptor cells are chemoreceptors and provide 75-80% of sense of taste
- Olfactory neurons have knobs covered in cilia found in the upper part of the nasal cavity
- 400 different types which result in unique action potentials(allows for different smells/tastes)
○ Each receptor cell contains 1 type of membrane protein which codes for a certain odorant
- Undergo sensory adaptation quickly losing 50% of smell within 1 second of stimulation
18
Q
Olfactory athways
A
Once olfactory receptors are stimulated, nerve impulses travel through openings in cribriform plates to the olfactory cortex for interpretation and through the limbic system for emotions and memory
19
Q
Gustation
A
- From organs of taste; papillae of tongue, roof of mouth and lining of cheeks
- Chemoreceptors that are modified epithelial cells which microvilli protruding out of pores
20
Q
5 Types of Taste, what they are stimulated by, and where the organs they stimulate are
A
- Sweet is on the tip stimulated by carbs
- Sour is on the side of tongue stimulated by acids
- Salty is on the sides of the tongue stimulated by salts
- Bitter is the back of the tongue(stimulates gag reflex) stimulated by mg, Ca salts
- Umami: all over the tongue stimulated by AA and MSG
21
Q
Taste Pathway
A
- Travel through the facial, glossopharyngeal nerve and vagus nerve to the medulla oblongata
- From there they are processed in the thalamus and interpreted in the gustatory cortex
22
Q
Ear Structure
A
External Ear:
- Auricle
- External acoustic meatus
- tympanic membrane
Middle Ear: - Tympanic cavity - Auditory ossicles(malleus, Incas, stapes): vibrate in response to noise - Oval window Inner Ear: - Auditory eustachian tube: helps maintain equal air pressure through valve like flaps which are closed - Round window: on the inner wall of the tympanic cavity dissipates excess vibrations - Osseous labyrinth - Membranous labyrinth ○ Cochlea ○ Semicircular canals ○ Vestibule
23
Q
Cochlea and the 3 membranes
A
the spiral snail shaped tube composed of the scala vestibuli, the scala tympani and the cochlear duct
Membranes of the Cochlea:
- Vestibular membrane
- Basilar membrane
- Tectorial membrane
24
Q
Middle Ear Infection
A
bacteria that is caught in the mucous membranes and middle ear tube
25
Auditory Pathway
1. Cochlear branch of vestibulocochlear nerve
2. Medulla oblongata
3. Midbrain
4. Thalamus
Auditory cortex in temporal lobe of cerebrum
26
2 types of Hearing Loss
- Conductive deafness: interference with conduction of sound vibrations to inner ear caused by injury to the tympanic membrane, ossicles or accumulation of ear wax
- Sensorineural deafness: damage to the cochlea, vestibulocochlear nerve or nerve pathways due to long term exposure to loud sounds
27
2 Types of Equilibrium
- Static equilibrium: senses position of head when body is not moving due to receptors found in the vestibule of inner ear
- Dynamic Equilibrium: senses rotation and movement of head and body due to receptors in semicircular canals.
28
Static Equilibrium organs
- Organs Locate in vestibule between cochlea and semicircular canals
- Utricle and Saccule are expanded chambers of the membranous labyrinth
- Bending of hairs in Malacula results in generation of nerve impulses in the vestibular branch of vestibulocochlear nerve
29
Dynamic Equilibrium Organs
receptors are found in the 3 semicircular canals which sight at right angles to each other
Each canal contains an ampulla which is a membranous labyrinth contains crista ampullaris that has hair cells which when stimulated send nerve impulses over the vestibular branch of the vestibulocochlear nerve
30
Sense of Vision
visual receptors are found in the eye
- Accessory organs include
○ Upper and lower eyelids
○ Eyelashes
○ Lacrimal apparatus
○ Extrinsic eye muscles
31
Eye lid: structure
composed of 4 layers:
- Skin
- Muscle: orbicularis oculi
- Connective tissue: tarsal glands which secrete oil
Conjunctiva: mucous membrane that lines eyelid and covers portions of the eyeball
32
Lacrimal Apparatus
- Lateral and superior to the eye which secretes tears into the eyes obliquely, collecting in canaliculi
- Tears contain lysozyme which breaks down bacterial cell walls
33
Eye: Structure
hollow, spheric organ of sight which has 3 layers:
- Outer fibrous tunic:
○ Cornea: window of eye which focuses light rays and refracts light
○ Sclera: outer layer which protects eye and attaches muscles
- Middle vascular tunic:
○ Iris: controls light entering eye
○ ciliary body: forms ring to hold lens, changes lens shape
○ choroid coat: contains melanocytes which absorb light
- Inner nervous tunic:
○ Retina: contains photoreceptors that are continuous with the optic nerve
34
Anterior Portion of Eye
contains the anterior cavity which is between the cornea and lens and filled with aqueous humor
- Helps focus light rays
- Aqueous humor provides nutrients and helps maintain shape of anterior portion
35
Ciliary Body
forms internal ring around front of the eye
- Ciliary processes are the radiating folds
- Ciliary muscles contract to relax and move lens
- Suspensory ligaments hold the lens in place
36
Accommodation:
the process of the lens changing in shape to view objects due to the ciliary muscles relaxing or tightening the suspensory ligaments
- Lens thickens and becomes more convex when focusing on close objects
- Lens thins and becomes flatter when focusing on distant objects
37
Iris
controls the amount of light entering the eye and is composed of connective tissue and smooth muscle
- Pupil is the window in center of iris
- Dim light causes pupil to dilate, while bright light stimulates pupil to constrict
38
Posterior Cavity
space enclosed by the lens, ciliary body and retina which contains the vitreous body
- Vitreous body is composed of collagen fibers and vitreous humor which is a thick gel holding the retina flat against the choroid
39
Light Refraction
the bending of light which occurs when light waves pass at an angle between mediums of difference densities so the image falls on the fovea centralis
- Convex lense: causes light waves to converge
- Concave lenses: cause light waves to diverge
- This occurs in the eye as it passes through the cornea and lens, making the image upside down and reversed, and then in our visual cortex we correct the reversals of the image
40
Vision/refraction Disorders
- Presbyopia(farsightedness by age): accommodation becomes impossible due to loss of elasticity in lens
- Myopia(nearsightedness): light focuses in front of retina, creating blurry images for distant objects
○ Corrected by concave lens
- Farsightedness(hyperopia): light focuses in back of retina, creating blurry images for close objects
○ Corrected by convex lens
- Astigmatism: defect in curvature of cornea or lens resulting in some parts of the image being in focus while others are blurry
41
Photoreceptors and the 2 types
modified neurons of retina that sense light
Types:
- Rods: long thin projections which are more sensitive to light and provide vision in dim light as well as produce vision in shades of gray and the outlines of objects
- Cones: short, blunt projections which provide vision in bright light, sharp images, color vision
42
Stereoscopic Vision
our eyes can see height, depth and width due to distance between our pupils which allows overlapping images to be combined in the visual cortex
43
Visual Pathway
- Proceeds from the ganglion cells of the retina to the optic nerve
- Goes through the optic nerve to the chiasma, tracts and to the thalamus and visual cortex in occipital lobe of cerebrum
- Few fibers branch off before reaching the thalamus and enter nuclei for visual reflexes and head/eye tracking movements
