HEENT Anatomy Flashcards
The Special Senses Include?
Smell, Taste, Vision, Hearing, and Balance
The General Senses include?
Somatic Senses
Visceral Senses
Somatic Senses include?
- Tactile Sensations (Touch, Pressure, and Vibration.
- Thermal Sensations (Warm and Cold)
- Pain Sensation
- Proprioceptive sensations (Joint and Muscle Position sense and movements of the limbs and head)
Visceral Senses provide?
Information about conditions within internal organs
The Conscious or subconscious awareness of change in the external or internal environment is?
Sensation
Four conditions for Sensation to occur?
- Stimulus
- Sensory Receptor
- Conduction of nerve impulses
- Integration from the Brain
What is a Stimulus?
A change in the environment, capable of activating certain sensory neurons.
- Ex: Light, heat, pressure, mechanical energy, or chemical energy
What is the job of a Sensory Receptor during a Sensation?
Must convert the stimulus to an electrical signal which ultimately produces one or more nerve impulses if it large enough.
How does Conduction work during a Sensation?
Nerve impulses must be conducted along a neural pathway from the sensory receptor to the brain.
How does Integration play a role during a Sensation?
A region of the brain must receive and integrate the nerve impulses into a sensation.
What characteristic do most sensory receptors share?
Adaptation
Adaptation is?
A decrease in strength of a sensation during a prolonged stimulus
What is an important result of Adaptation?
the perception of a sensation may fade or disappear even though the stimulus persists.
Ex: first stepping in to a hot shower, and over time the sensation becomes more comfortable.
Which types sensations where receptors Adapt rapidly?
Pressure, Touch, and Smell
Which types of sensations receptors Adapt slowly?
- Pain
- Body Position
- Chemical Composition of the Blood
How are Sensory Receptors grouped into different classes?
Structure and Function
Structural Groups of Receptors
Free nerve endings
Encapsulated Nerve Endings
Separate Cells
Free Nerve Endings
Bare dendrites associated with pain, tickle, itch, some touch sensation
Receptors for pain, temperature, tickle, itch and some touch sensations are?
Free nerve endings
Dendrites enclosed in a connective tissue capsule for pressure, vibration, touch.
Encapsulated Nerve Endings
Which receptors have Separate Cells and how do Separate Cells work?
- Receptor cell synapses with first order neuron
- Located in retina (photoreceptors), inner ear (hair cells), and taste buds
Functional groups of Receptors
Mechanoreceptors Nociceptors Photoreceptors Chemoreceptors Osmoreceptors
Detect mechanical pressure; provide sensations of touch, pressure, vibration, proprioception, and hearing and equilibrium.
- Also monitor stretching of blood vessels and internal organs
Mechanoreceptors
Respond to painful stimuli resulting from physical or chemical damage to tissue
Nociceptors
Detect light that strikes the retina of the eye
Photoreceptors
Detect chemicals in mouth (taste), nose (smell), and body fluids
Chemoreceptors
Sense the osmotic pressure of body fluids
Osmoreceptors
What do the Tactile sensations include?
- Touch
- Pressure
- Vibration
- Itch
- Tickle
Within the tactile sensations, what type of receptors detect touch, pressure, and vibration?
Encapsulated Mechanoreceptors (Encapsulated need more of a robust stimulus)
Tactile sensations such as itch and tickle are detected by?
Free Nerve endings (more sensitive to lighter stimulus)
Tactile receptors in the skin or subcutaneous layer include ?
Meissner corpuscles, hair root plexuses, Merkel discs, Ruffini corpuscles, pacinian corpuscles, and free nerve endings
What are the two touch receptors?
Meissner Corpuscles and Hair Root Plexuses
* Rapidly adapting*
What is a Corpuscle?
An egg-shaped mass of dendrites enclosed by a capsule of connective tissue
Where are Meissner Corpuscles located and most abundant?
Located in dermal papillae or hairless skin
Most abundant:
Finger tips, hands, eyelids, tip of the tongue, lips, nipples, soles, clitoris, and tip of penis
What do Hair Root Plexuses consist of?
Free nerve endings wrapped around their hair follicles
What is the main job of a Hair Root Plexus and an example of that action?
Detect movements on the skin surface that disturb hairs
Ex: an insect landing on a hair causes movement of the hair shaft that stimulates free nerve endings
What are the two types of Slowly adapting touch receptors?
- Merkel discs (aka Tactile discs or type I cutaneous mechanoreceptors)
- Ruffini corpuscles (type II cutaneous mechanoreceptors)
A sustained sensation that is felt over a larger area and occurs in deeper tissues than touch, occurs with deformation of deeper tissues?
Pressure
Receptors that contribute to sensations of pressure include?
- Meissner corpuscles
- Merkel discs
- Pacinian or Lamellated Corpuscle
What are some characteristics of Pacinian Corpuscles?
- Adapt rapidly
- Widely distributed throughout the body:
- Dermis and subcutaneous layer
- Tissues underlying mucous and serous membrane
- around Joints, Tendons, and Muscles
- Periosteum
- Mammary Glands, external genitalia
- Pancreas and Urinary bladder
In vibration sensation, how do the Meissner corpuscles and pacinian corpuscles detect vibrations differently?
Meissner - lower frequency vibrations
Pacinian - higher frequency vibrations
What results from stimulation of free nerve endings by certain chemicals or because of a local inflammatory response?
Itch sensation
What chemical stimulates an Itch sensation
Bradykinin
PT’s who have had a limb amputated may still experience sensations such as itch, tingling, or pain as if the limb was still there. What is the name of this phenomenon?
Phantom Limb Sensation
Thermoreceptors have what type of receptors?
Free nerve endings
What temperatures activate Cold Receptors and where are they located?
Temps between 10 deg to 40 deg C (50-105F)
- Epidermis
What temperatures activate Warm Receptors and where are they located?
Temps between 32 and 48 deg C (90-118F)
- Dermis and Epidermis
What happens to cold and warm receptors throughout a stimulus?
They both adapt RAPIDLY at the onset of a stimulus but continue to generate nerve impulses more SLOWLY through prolonged stimulus
Temperatures below 10deg C and above 48deg C stimulate?
Nociceptors producing a painful sensation to extremes
What type of receptors do Nociceptors have and where are they found?
- Free nerve endings
Found in every tissue BESIDES THE BRAIN
The lack of adaptation of Nociceptors is important because?
It serves a protective function
- If adaptation occurred, irreparable tissue damage could occur
What are the two types of Pain?
Fast and Slow
Fast Pain
- Known as acute, sharp, or prickling (Knife cut or needle puncture)
The perception of fast pain occurs very rapidly
- within 0.1 sec after stimulus
T/F Fast Pain is felt in deeper tissues of the body
False. Slow pain is
Slow Pain
Felt a second or more after stimulus
- Gradually increases intensity over time
- Referred to as Chronic pain
- Can be burning, aching, or throbbing pain (toothache)
Where is Slow Pain felt?
Skin, Deeper tissues, and internal organs
How is the localization of Fast and Slow pain different?
Fast pain - precisely localized to the stimulated area
Slow pain - somewhat localized but more DIFFUSE
What is Referred Pain?
Pain felt in or just deep to the skin that overlies the stimulated organ.
- Or in a surface area far from the stimulated organ
What causes Referred pain to be felt in a surface area far from the site of stimulation?
The same segment of the spinal cord usually serves the visceral organ involved and the area of pain
What is pain that persists for longer than two or three months?
Chronic Pain
What allows us to know where our head and limbs are located and how they are moving even if we are not looking at them?
Proprioceptive Sensations
Kinesthesia
Perception of body movements
Where are proprioceptors located?
- Skeletal Muscles (Muscle spindles)
- Tendons (Tendon Organs)
- Synovial Joints (joint kinesthetic receptors)
- Inner Ear (hair cells)
What proprioceptors monitor the orientation of the head relative to the ground and positioning during movements?
Hair Cells in the inner ear
Where do nerve impulses for conscious proprioception travel?
Through tracts in the spinal cord and brain stem then relayed to:
PRIMARY SOMATOSENSORY AREA
(Post central Gyrus)
The study that deals with the eye and its disorders?
Ophthalmology
The science that deals with the Ears, Nose, and Throat and their disorders
Otorhinolaryngology
What is the term for smell and how many receptors are involved?
Olfaction
10-100 million receptors in the nose
What occupies the upper portion of the nasal cavity?
Olfactory Epithelium
What are the 3 types of cells in the Olfactory Epithelium?
- Olfactory Receptors
- Supporting Cells
- Nasal Stem Cells
What are the first-order neurons of the Olfactory pathway?
Olfactory Receptors
What projects from a knob-shaped tip on each olfactory receptor?
Olfactory hairs
Chemicals that have an odor and can therefore stimulate the olfactory hairs?
Odorants
The axons of the olfactory receptors extend from the olfactory Epithelium to the?
Olfactory Bulb
Columnar Epithelial Cells of the mucous membrane lining the nose
Supporting Cells
What do the Supporting Cells do?
Provide physical support, nourishment, and electrical insulation for the olfactory receptors and help detoxify chemicals that come in contact with the olfactory epithelium
Stem cells located between the bases of supporting cells and continually undergo cell division to produce new olfactory Receptors
Basal Cells
Why is the process of Basal cells producing olfactory receptors significant?
Olfactory Receptors are neurons and in general, mature neurons are not replaced
What produces mucus that moistens the surface of the olfactory epithelium and serves as a solvent for inhaled odorants?
Olfactory glands
How does adaptation occur to odors by olfactory receptors?
Adaptation (decreasing sensitivity) to odors rapidly.
Olfactory receptors adapt by 50% in the first second or so after stimulation and very slowly after that.
Which types of cells for the Olfactory Nerves (I)?
40 bundles of UNMYELINATED axons of olfactory receptors that extend through the cribiform plate of the ethmoid bone.
Where do the Olfactory Nerves terminate?
The olfactory bulbs (paired masses of gray matter), located below the frontal lobes of the cerebrum
How do neurons connect within the olfactory bulbs?
The axon terminals of olfactory receptors (1st Order neurons) form synapses with the dendrites and cell bodies of 2nd order neurons in the olfactory pathway
What forms the Olfactory tract?
The axons of the neurons extending from the olfactory bulb
At what location does the conscious awareness of smell begin?
The Primary Olfactory area
- Temporal Lobe of Cerebral Cortex
What two locations does the olfactory tract project to?
- Primary Olfactory Area
- Limbic System and Hypothalamus
What is Hyposmia?
Reduced ability to smell
- Affects half of those over 65 yo, and 75% of 80yo
What are the 5 primary tastes?
- Sour
- Sweet
- Bitter
- Salty
- Umami
How do odors of food affect taste?
Olfaction can be stimulated thousands of time more strongly than gustation.
- When you have a cold or allergies, and cannot taste food, it is olfaction that is blocked not gustation
Where are the receptors for taste sensation found in?
Taste buds
T/f: The number of taste buds declines with age
True
Elevations of the tongue where taste buds are found, and provide a rough texture to the tongue?
Papillae
Inverted V-shaped row of papillae at the back of the tongue
Vallate papillae
Mushroom shaped elevations scattered over the entire surface of the tongue
Fungi-form papillae
Threadlike papillae found in the entire surface of the tongue that contain touch receptors, but no taste buds
Filiform papillae
Three types of Epithelial cells in Taste Buds
- Supporting Cells
- Gustatory Receptor Cells (50)
- Basal Cells