Chapter 23 Flashcards
What makes it possible for the body to respond to stimuli caused by changes occuring in our internal or external environment
Sensory receptors
Sensory receptors are crucial for
Survival and homeostasis
The general function of receptors is to
Respond to stimuli by converting them to nerve impulses
Different types of receptors respond to
Diferent stimuli
A ________ is a local potential that develops in a receptors membrane when an adequate stimulus acts on a receptor
Receptor potential
A receptor potential is a ____ response
Graded
When a receptor potential reaches a certain threshold it triggers a
Action potential
The action potentials/impulses travel over sensory pathways to the brain and spinal cord where
T hey are either interpreted as a particular sensation or initiate some type of reflex action (e.g. pulling your hand away from a flame
________ is a functional characteristic of receptors
Adaptation
Adaptation really refers to
The process that causes the receptor potential to decrease over time in response to a continuous stimulus, which leads to a decreased rate of impulse conduction and a decreased intensity of sensation
Special sense
Receptors for special senses of smell, taste, vision, hearing, and equilibrium are grouped into localized areas (e.g. taste buds on the tongue) or into complex organs (e.g. eyes)
General sense organs
microscopic receptors widely distributed throughout the body in the skin, mucosa, connective tissue, muscles, tendons, joints, and viscera
3 classification by location
Exteroceptors
Interoceptors/ visceroceptors
Proprioceptors (special type of visceroceptor)
Exteroceptors
On or near body surface
Often called cutaneous receptors;
Example: pressure, touch, pain, temperature
Interoceptors/ visceroceptors
Located internally- often within the bodys organs/viscera
Provide body w/ info about internal environment such as pressure, stretch, chemical changes, hunger, thirst
Proprioceptors
A special type of interoceptor/ visceroceptor
Location limited to skeletal muscle, joint capsules and tendons
Provide info on body movement, orientation in space and muscle stretch
Two types of proprioceptors and what they do
Tonic and phasic
Provide positional info on body or body parts while at rest (tonic) or during movement (phasic)
Classification by stimulus detected (6)
Mechanoreceptor Chemoreceptors Thermoceptors Nociceptors Phoreceptore Osmoreceptors
Mechanorreceptors
Actived when deformed
Chemoreceptors activated by
Certain chemicals eg smell or taste
Thermoreceptors activated by
Changes in temperature
Nociceptors activated by
Intense stimuli that may damage tissue (sensation produced is pain)
Photoreceptors respond to ____ and only found in _____
Respond to light stimuli
Eyes
Osmoreceptors are concentrated in ______ activated by _________.
Involved in ____ mechanism
Concentrated in the hypothalamus
Activated by changes in concentration of electrolytes (osmolarity) in extracellular fluids
Involved in thirst mechanism
Free nerve endings
Simplest, most common, and most widely distributed sensory receptor
Located on surface of body (exteroceptors) and deep in visceral organs (interoceptors/visceroceptors)
Detect pain, temperature, and tactile sensation
Classification of receptors by structure
Free nerve ending
Capsulated
Encapsulated nerve endings
Structure includes some type of connective tissue capsule that surrounds dendritic end of receptor
Most often activated by a mechanical (deforming) type of stimulus
Vary in size, structure, numbers, and distribution
6 types subdivided into 2 main ‘categories’:
Touch and pressure receptors
Stretch receptors
Four general senses are
Pain
Temperature
Touch
Proprioception
Two types of pain
Acute (fast)
Chronic (slow)
