1. Sensory, Motor, and Integrative Systems
BIO 137 ANTOMY & PHYSIOLOGY I

2. General Sensations
In this chapter we explore the levels and components of pathways that convey sensory nerve impulses from the body to the brain, and the general sensations (somatic and visceral) that result. We will
also examine the activation of
motor pathways and movements
In chapter 17 we will look at
the special senses of sight,
hearing, taste, and smell

3. Special Senses Comparing the general senses and the special senses
Include somatic sensations (tactile, thermal, pain, and proprioceptive) and visceral sensations
Are scattered throughout the body
Are relatively simple structures
Special Senses
Include smell, taste, vision, hearing and equilibrium
Are concentrated in specific locations in the head
Are anatomically distinct structures
Form complex neural pathways

4. Sensory Receptors Receptors detect a stimulus inside or outside a cell
They transmit a sensory impulse (action potentials) to the appropriate area of the cerebral cortex
Each piece of incoming information is combined with other arriving and previously stored information in a process called integration
What is the relay station for this information????

5. Sensations and Perception
A sensation is the initial awareness of a stimulus (sensory impulse)
Smell something sweet
Perception is the way the brain interprets a sensation
Smell of a banana
Your perception is your reality
Projection occurs when the cortex projects the sensation back towards the sensory receptor
You smell the banana with your nose

6. Sensory Adaptation
Adjustment of sensory receptors to continuous stimulation
Sensory Receptor becomes less responsive to continuous stimulation
A stronger stimulus is required to activate receptors
i.e. entering a very ‘smelly’ location and adapting

7. Sensory Receptor Types
Receptors can be classified by the type of stimulus they detect
Chemoreceptors
Photoreceptors
Mechanoreceptors
Thermoreceptors
Pain receptors
Proprioceptors

8. Sense Receptors Chemoreceptors
Respond to changes in concentrations of chemicals
O2 or CO2 levels in blood
Odorants
Ions
Dissolved Food

9. Receptor Types Photoreceptors Pain receptors (nociceptors)
respond to light
cones and rods in retina of eye
Pain receptors (nociceptors)
respond to tissue damage
distributed along with all receptors above, except in the brain
Mechanoreceptors
Sense mechanical forces (pressure, touch)

10. Thermoreceptors Heat receptors
sensitive to temperatures above 25oC (77o F)
unresponsive to temperature above 45oC (113oF)
Produce burning sensation near that temperature (PAIN)
Cold receptors
sensitive to temperatures between 10oC (50oF) and 20oC (68oF)
Produce freezing sensation near that temperature (PAIN)
Thermoreceptors undergo sensory adaptation

11. Tactile System: Sense of Touch
1st sensory system to develop in the womb and the largest sensory system in the body
Touch affects development and expansion of our brains into adulthood
Studies show infants deprived of touch show developmental delays, stunted growth and abnormal cortisol levels
Tactile receptor locations
Skin, lining of mouth & throat, digestive system, ear canal, covering organs…..

12. Types of Touch Light Touch Deep Pressure Vibration Temperature Pain
Meissner’s Corpuscles
Feel of sand, washing your hair or face
Deep Pressure
Pacinian Corpuscles
Bear hugs, massage
Vibration
Temperature
Pain

13. Sense of Pain Detected by nociceptors (DO NOT ADAPT)
Widely distributed throughout skin and internal tissues (except nervous tissue of brain)
Stimulated by tissue damage, chemicals, low blood volume or O2 or extremes in temperature
Function is to protect tissues from further damage

14. Abnormality of Perception
Visceral pain results from stimulation of nociceptors in visceral organs
Visceral Pain may present as considered referred pain
The pain is felt in or just deep to the skin that overlies the stimulated organ, or in a surface area far from the stimulated organ.
Pain is felt in an area of the body that is different than where the actual stimulus is
Occurs because of shared common sensory nerve pathways to the spinal cord from the skin and internal organs

15. Referred Pain
may occur due to sensory impulses from two regions following a common nerve pathway to spinal cord
12-11

16. Nociception
Common patterns of referred visceral pain are shown in this graphic

17. Proprioception
Sense associated with awareness of position of body parts in space
Proprioceptors are mechanoreceptors located within joints, tendons, ligaments, connective tissue and muscles that monitor joint movement
Transmit information about muscle contraction, position of joints and location of the head to the brain

18. Proprioception No conscious awareness of this sense
While performing a task, you are not always aware of where your body parts are (or at least not thinking about them)

19. Somatic Sensory Pathways
Somatic sensory neurons (and their axons that convey somatic sensations) are not distributed evenly in the body
The peripheral areas with the highest density
are represented in the brain with the largest
amount of gray matter cortex.
The most sensitive areas in the body are
therefore the tip of the tongue, lips, and
Fingertips.

20. Somatic Motor Pathways
Motor activity begins in the primary motor areas of the precentral gyrus and other cerebral integrative centers
The basal nuclei and cerebellum influence movement through their effects on upper motor neurons.

21. Sensory Integration or Processing
All sensory input is processed together in the brain in many of the same structures
SI is the neurological process of organizing sensations for use in everyday life
refers to how people use this sensory info
Because the senses are integrated, we assign meaning to sensory experiences and know how to respond and behave accordingly

22. Sensory Integration
SI usually occurs without conscious thought or effort
That is, you can multitask while conversing
Ironing while talking, cleaning while talking
You can normally tune out unimportant stimuli

23. Normal Sensory Processing
As sensory processing skills mature, neural pathways become stronger and more myelinated
Can filter out what is not important at a given time so you can focus on what is needed

24. Impairments in Sensory Processing
The senses do not integrate efficiently
Interferes with learning and development, social interaction, everyday activities
Estimated to affect 10-15% of children
People with SID do not have accurate information about their senses and may react inappropriately

25. SI Dysfunction
Do not have this discriminative ability to filter out senses
The brain inefficiently processes sensory information
Sensory Neural pathways are not as developed

26. ‘Seek out a sensation or avoid a sensation’

27. Limbic System and SI
Limbic system must be involved in processing sensory info
Controls emotional response to a stimulus
If can not normally process sensory info, limbic system shuts down and you can not process ANY more sensory info
‘Hands over the ears’

28. Proprioception Abnormalities
Difficulty with motor planning
What do I do?
Difficulty with motor control
How do I do it?
Poor proprioception in fingers
Difficulty with fine motor skills
Manipulation with the wrist and fingers
Writing, buttoning
Poor muscle tone

29. Tactile Abnormalities
Avoids sticky substances
Avoids sand, dirt, getting dirty
Does not like tags in clothing
Won’t eat certain foods because of the texture

30. Plasticity Capacity for the brain to change at any age
Decreases with age
We learn through strengthening or weakening synapses

31. Sensory Integration Therapy
Provide different types of sensory stimulation
Through plasticity, strengthen neural pathways for each of the senses
Allows individuals with SID to process sensory stimuli effectively