Module 3.1- Afferent System Flashcards
Discuss the receptors and processes involved in olfaction, gustation and vision. Describe the parts of the ear and their roles in the process of hearing. Identify the parts of the eye and their functions. Discuss how the central nervous system processes information related to all of the senses
What are afferent nerves?
Nerves that relay information from periphery nervous system to the central nervous system.
What is another name for the afferent nerves?
Sensory nerves
What are efferent nerves?
Nerves that send information from the Central nervous system to the peripheral effector cells.
What is another name for efferent nerves?
Motor nerves
What are the two components of the efferent nervous system?
Somatic nervous system and autonomic nervous system
What is the somatic nervous system?
Fibres of motor neurons that supply skeletal muscles and regulate its contractions
What is the autonomic nervous system?
Innervates and regulates non-motor organs such as smooth and cardiac muscle, glands, blood vessels and other internal organs.
What is exteroception?
Means by which the nervous system receives information about the external environment
What is interoception?
Means by which the nervous system receives information about the internal environment.
What is propeioception?
Means by which nervous system receives information about the position and movement of the body.
How does the body subconsciously use sensory information, without the participation of the conscious parts of the brain?
To generate reflex actions
Is all sensory information used in conscious perception?
Not all, but most.
Where is sensory information directed for conscious perception?
The cerebral cortex.
What is sensation?
Conscious perception of sensory stimuli
How can one figure out what an animal sees/feels/hears/smells?
Impossible to know exactly but inferences can be made by observing the animals reaction to selected stimuli.
Are receptors capable of detecting both internal and external environments?
Yes
What kinds of stimuli can receptors respond to?
Sound waves, Light waves, Pressure, Temperature, Chemicals.
Where are sensors found?
Scattered throughout the body
What are sensory receptors?
Specialised neuronal structures.
What do sensory receptors do?
Convert detected stimuli into electrical energy for transduction.
Sensory neurons may be specialised how?
Ending of an afferent neuron (eg pain receptors).
Separate cells (retina photoreceptors).
Closely associated with ending or a peripheral neuron.
What organs are sensory receptors found in?
Sense organs
Are sensory receptors specialised to receive one or more stimuli?
Only one stimuli, eg photoreceptors interpret light waves
Do receptors interpret stimuli?
No, They are transducers that receive stimuli and generate nerve impulses
How do receptors receive stimuli?
They have a low threshold to respond to one particular stimulus, they receive that stimuli acting as a transducer and generate a nerve impulse for the brain to interpret.
What organ/s interpret stimuli?
The brain
Can the whole brain interpret stimuli?
Only specific regions of the brain can process information from specific receptors.
What does the brain interpret the nerve impulsed generated by sensory receptors into?
Sensation/s
What does a Mechanoreceptor respond to?
Physical deformation
What does a Thermoreceptor respond to?
Both heat and cold (temperature)
What does a Nociceptor respond to?
Stimuli potentially injurious to tissue (noxious stimuli)
What do Photoreceptors respond to?
Light waves.
What do Chemoreceptors respond to?
Chemical changes associated with:
taste (chemicals dissolved in saliva)
Smell (chemicals dissolved in mucus)
Pain (chemicals in ECF)
Blood O2 (O2 dissolved in plasma)
Blood PH and CO2 (Free H ions and CO2 in plasma)
Satiety (Chemical content of digestive tract)
Thirst (osmotic concentration of key fluid molecules)
What does somatosensation encompass?
Pain, stoicism, proprioception
Describe somatosensation of pain
It’s the conscious perception of noxious stimuli (one capable of producing tissue damage). It can be thermal, chemical or mechanical stimuli. The ability of the stimulus to produce the sensation of pain is a highly mutable property that can be modified in the periphery, spinal cord and brainstem.
Describe somatosensation of stoicism
Apparent indifference to pain. It’s largely determined by personality and training e.g. Highly strung animals often exhibit exaggerated reactions to stimuli
Describe somatosensation of proprioception
Non-visual perception of body position. Complex sensation made up of responses of a variety of specialised receptors (Joint receptors, muscle spindles, golgi tendon organs and skin mechanoreceptors)
What do joint receptors do?
Receive information on tension and pressure within joints
What do muscle spindles do?
Signal changes in muscle length
What do golgi tendon organs do?
Signal tension in tendons
What do skin mechanoreceptors do?
Report contact between the skin and surrounding environment
What are visceral sensations?
Involve structures within body cavities. Most information interpreted by visceral afferent system not interpreted consciously but is used in directing autonomic activity in viscera.
What receptors are found in the viscera?
Mechanoreceptos and chemoreceptors
What stimuli is the viscera especially sensitive to?
Crushing, cutting and thermal injury.
Also responds vigerously to stretch, dilation, tension and ischaemia (decreased blood flow)
What is referred pain?
Occurs when noxious stimuli found in the viscera is perceived as originating from the somatic region (body wall or skin)
What is a common example of referred pain in humans?
Ischaemia (reduced blood flow) of the heart muscle is usually perceived as radiating across left shoulder and down left arm
What is a common example of referred pain in animals?
Hardware disease; Cattle may exhibit a high degree of sensitivity around the sternum, with traumatic gastritis caused by a wire or nail perforating the wall of the forestomach
What are two types of senses that detect chemicals from the external environment to interpret them as sensations?
Gustation (taste) and Olfaction (smell)
Which animals have chemoreceptors?
Most, it is thought to be the most primitive sense.
Where are chemoreceptors found in crustacea?
On antennae and appendages
Where are chemoreceptors found in insects (eg houseflies)?
Gustation (taste) sensors found on feet
Where are chemoreceptors found in amphibians?
In the mouth and all over skin
Where are chemoreceptors found in mammals?
Gustation (taste) receptors in mouth, Olfactory (smell) receptors in nose
