Sensory Receptors Flashcards
(36 cards)
What is the role of sensory receptors?
They change sensory stimuli (touch/temp) into nerve signals that are then conveyed to and processes in the CNS
Name the 5 basic types of sensory receptors
1) Mechanoreceptors -
2) Thermoreceptors
3) Nociceptors (pain receptors)
4) Electromagnetic receptors
5) Chemoreceptors
Describe the function of mechanoreceptors
1) Mechanoreceptors - detect mechanical compression or stretching of the receptor or tissue adjacent to the receptor
Describe the function of thermoreceptors
Thermoreceptors - Detect changes in temperature with some detecting cold and some warmth.
Describe the function of nociceptors
3) Niciceptors (pain receptors) - detect physical or chemical damage occurring in tissue (free nerve endings)
Describe the function of electromagnetic receptors
4) Electromagnetic receptors - Detect light on the retina of the eye
Describe the function of chemoreceptors
Chemoreceptors - Detect taste in mouth, smell in nose, oxygen levels in arterial blood, osmolality in body fluids and other factors that make up chemistry of the body.
Name the two types of mechanoreceptors
Skin tactile sensibilities (in the dermis and epidermis)
Deep tissue sensibilities
Name the types of endings in skin tactile sensibilities
Free nerve endings, expanded tip endings (eg, merkel’s discs), spray endings (Ruffini’s endings), Encapsulated endings (Meissner’s corpuscles and Krause’s corpuscles) and finally Hair end-organs
Name the types of endings in deep tissue sensibilities
Free nerve tip, expanded tip endings, spray endings (Ruffini’s endings), Encapsulated endings (eg, Pacinian corpuscles) - Same as skin tactile
Others are Muscle endings, Muscle spindles and golgi tendon receptors.
Describe some of the features of the pacinian corpuscles
- Largest mechanoreceptor
- Found in deep layer of the dermis
- Detects high frequency vibrations
- A,beta fibres found in both glabrous and hairy skin
- Rapidly acting due to slick viscous layers
- Low activation threshold meaning it is sensitive
Describe some of the features of Meissner’s corpuscles
- Encapsulated nerve endings similar to pacini’s but are much smaller.
- They have stacks of discs with nerve branches between them
- Found between dermal papillae and detect low frequency vibrations, flutters and touch
- A,Beta fibres found in glabrous skin types
- Low activation threshold so its sensitive
Describe some of the features of Merkel Disks (structure, fibres, adaptation ect)
- Non-encapsulated nerve endings which detect static tough and light pressure
- A,beta fibres found in all skin types
- Slowly adapting
- Found just under the skin and are good for discrimination
- They have multiple branches found in ‘iggo dome
- Work with meissner’s corpuscles
Describe some of the features of Ruffini Corpuscles (Response, location ect)
They respond to skin stretch and are located in deep layers of the skin as well as tendons sand ligaments.
Encapsulated nerve endings found in all skin types. The nerve endings weave between collagen fibres which activate them when pulled longitudinally.
Describe some of the features of skin hair cell receptors
Mechanosensitive receptors wrapped around its follicle. It detects muscular movement of erector muscle and external displacement of hair
Where are other places you can find mechanoreceptors?
- In the ear where they act as sound receptors of the cochlea
- Vestibular receptors which are found in the ear and help balance
- Baroreceptors in coratid sinus and aorta to regulate arterial pressure
Where will you find chemoreceptors and what to they respond to?
- Receptors of taste buds, respond to taste
- Receptors of olfactory epithelium to respond to smell
- Receptors of aortic and carotid bodies that respond to arterial oxygen
- Receptors near/in supraoptic nuclei to respond to osmolality
- Receptors on/in medulla and in the aortic and carotid bodies to respond to blood CO2
- Receptors in hypothalamus to respond to blood glucose, amino acids and fatty acids
Once a receptor is stimulated what is the immediate effect?
A change to the membrane electrical potential, this is called the receptor potential
What is another word for receptor potential?
Generator potential
A receptor/generator potential can be created by?
Mechanical deformation which stretches receptor membrane and opens ion channels
- Application of chemical to membrane which opens ion channels
- Change in membrane temp which changes permeability
- Effects of electromagnetic radiation
What occurs when the receptor potential rises above the threshold?
An action potential occurs in the nerve fibres attached to the receptor
What occurs with a larger receptor potential?
Larger receptor potentials means a greater action potential frequency
Describe the relationship between the stimuli intensity and the action potential
The greater the intensity of a stimuli then the higher the frequency of the action potentials in the sensory nerve which is traveling to the CNS
How does the body know the modality of a stimuli? (whether its pain or touch or light ect) and what is this called?
Because the nerves terminate at a specific point in the CNS and therefore the type of sensation felt is determined by the point in the CNS where the fibre leads. This is called the Labelled Line Principle
