General And Special Senses - Chapter 18 - Human Anatomy - Incomplete

Front 1

Sensory receptor

Back 1

Specialized cell or cell process that monitors the conditions in the body or the external environment. Stimulation of receptor directly or indirectly alters the action potential in the sensory neuron.

Front 2

Sensation vs perception

Back 2

Sensation: sensory information arriving at the CNS
Perception: conscious awareness of a sensation

Front 3

General senses

Back 3

sensations of:
temperature
pain
touch
pressure
vibration
proprioception (body position)

Front 4

Special Senses

Back 4

Smell (olfaction)
taste (gustation)
balance (equilibrium)
hearing
vision

Front 5

Special sense receptors vs general sense receptors

Back 5

Special sense receptors are structurally more complex than general sense receptors and localized in special sense organs.

General sense receptors are scattered throughout the body.

Front 6

Receptor specificity

Back 6

Each receptor has a characteristic sensitivity to some stimuli but not to others.

Front 7

What are the simplest receptors

Back 7

Free nerve endings (dendrites of sensory neurons)

Front 8

Receptive field

Back 8

area monitored by a single receptor cell

Front 9

How does stimuli arrive in CNS?

Back 9

As action potentials regardless of the form of the stimuli e.g. pressure vs light

Front 10

How is sensory information interpreted in CNS?

Back 10

Labeled line: connection between sensory neuron and cortical neuron; provides information about location and nature of stimulus

Sensory coding: pattern of action potentials; provide information about strength, duration, variation and movement of stimulus

Front 11

Tonic receptors

Back 11

Sensory neurons that are always active e.g photoreceptors of the eye

Front 12

Phasic receptors

Back 12

Normally inactive; become active when there is a change in conditions they are monitoring; provide information about intensity and rate of change of stimulus

Front 13

What receptors convey extremely complicated sensory information?

Back 13

Receptors that provide phasic and tonic coding e.g receptors that monitor position and movement of joints

Front 14

Adaptation (define and types)

Back 14

Reduction in sensitivity in presence of a constant stimulus.

Types: Peripheral (sensory) adaptation and central adaptation

Front 15

Peripheral (Sensory) adaptation

Back 15

Occurs when receptors of sensory neurons alter their level of activity; respond strongly at first but then activity declines due to synaptic fatigue.

Fast-adapting receptors: phasic receptors
Slow-adapting receptors: tonic receptors

Front 16

Central adaptation

Back 16

Occurs in the CNS along sensory pathways; conscious awareness of stimulus disappears even though sensory neurons are still active; involves inhibition of nuclei along sensory pathways

Front 17

What percent of sensory information reaches the cerebral cortex and conscious awareness?

Where is the rest processed?

Back 17

1%

The remaining is processed in spinal cord and brain stem.

Front 18

What are the sensory limitations of humans?

Back 18

1. Humans do not have receptors for every possible stimulus.
2. Our receptors have characteristic range of sensitivity.
3. A stimulus must be interpreted by CNS and that interpretation is not always a reality.

Front 19

The General Senses Receptors (detailed classification)

Back 19

Nocireceptors: pain
Thermoreceptors: pressure changes
Mechanoreceptors: touch and pressure
Chemoreceptors: changes in chemical composition of body fluids

Front 20

Nocireceptors

Back 20

Pain receptors
Three types: extreme temperature sensitive, mechanical damage sensitive, dissolved chemicals (from injured cells) sensitive
Structure: Free nerve endings

Front 21

Types of Pain

Back 21

Fast Pain
Slow Pain
Referred Pain

Front 22

Referred pain

Back 22

Pain sensations from visceral organs perceived as originating in a superficial regions that are innervated by the same spinal nerves

Front 23

Thermoreceptors

Back 23

Stimuli: changes in temperature
Structure: Free nerve endings
Types: Cold (three times as numerous) and warm receptors
Fast adapting

Front 24

Types of Mechanoreceptors

Back 24

Tactile Receptors (touch, pressure, vibration)
Baroreceptors (stretch or pressure within organ or blood vessel)
Proprioreceptors (position of joints and muscles, most complex general sensory receptor)

Front 25

Tactile Receptors

Back 25

Stimuli: touch, pressure, vibration
Types: Encapsulated and unencapsulted

Front 26

Unencapsulated tactile receptors

Back 26

Fine touch
Free nerve endings: light contact with skin
Tactile discs: light contact with skin and tonic
Hair root plexus: initial contact with hair shaft

Front 27

Encapsulated tactile receptors

Back 27

Tactile corpuscles: initial contact and low frequency vibrations
Lamellated corpuscle: initial contact (deep) and high frequency vibrations
Ruffini corpuscle: deep pressure, stretching and distortion of dermis, tonic

Front 28

Proprioreceptors

Back 28

Stimuli: position of joints, tension in tendons and ligaments and muscular contraction
Examples: muscle spindles, Golgi tendon organs

Front 29

Chemoreceptors

Back 29

Stimuli: small changes in chemical composition of body fluids e.g. pH, CO2 and O2
Location: Carotid and Aortic blood vessels and respiratory centers of medulla oblangata

Front 30

Olfactory organs (structure)

Back 30

Olfactory epithelium (olfactory receptors, supporting cells and basal cells

plus

Underlying connective tissue with olfactory (mucus) glands, blood vessels and nerves

Front 31

Olfactory receptors (structure)

Back 31

Highly modified neurons with cilia that project beyond the olfactory epithelium into the mucus layer for greater exposure to odorous substances.

Front 32

Olfactory pathways

Back 32

Axons from olfactory epithelium penetrate cibriform plate in bundles of twenty to synapse with secondary neurons in the olfactory bulb. The axons of second neurons travel through the olfactory tract to olfactory cortex, hypothalamus and limbic system

Front 33

Olfactory discrimination

Back 33

Despite no apparent structural difference, olfactory receptor populations have different sensitivities to different stimuli.

Front 34

Affect of aging on olfactory receptors

Back 34

Number of olfactory receptors decline with age and the remaining become less sensitive.