Chapter 14 : Integration of Nervous sys functions

Question 1

stimulus

Answer 1

environmental event that excites sensory receptors

Question 2

sensation

Answer 2

what is perceived in the brain when sensory receptors are stimulated
• may be conscious or unconscious
• differ in modality (the energy form associated with the stimulus), quality and quantity

Question 3

senses

Answer 3

the means by which the brain receives information about the environment and the body.

Question 4

Senses are divided into 2 groups

Answer 4

1) general senses : have receptors distributed over a large part of the body.
also divided into 2 groups: the somatic sense and the visceral senses.

2) o Special Senses
– modified neurons localized in sensory organs of head
• vision, hearing, taste, smell, rotational and linear acceleration of head

Question 5

Somatic sense

Answer 5

Provides sensory information about the body and the environment . This includes touch, pressure , itch, vibration, temp, and pain.

Question 6

Visceral sense

Answer 6

provide information about internal organs
• pain, stretch, chemoreceptors, baroreceptors, osmoreceptors

• consist primarily of pain and pressure.

Question 7

mechanoreceptors

Answer 7

respond to mechanical stimuli such as o compression, bending, stretching of cells.
The sense of touch , tickle , itch , vibration , pressure, hearing and balance all depend on a variety of mechanical receptors.

Question 8

chemoreceptors

Answer 8

respond to chemicals

o ex : taste, smell, plasma pH and concentrations of carbon dioxide and oxygen

Question 9

Thermoreceptors

Answer 9

detect changes in temperature

o cold receptor – increase rate of action potentials as skin is cooled (35o→12oC)
• 10-15 times more numerous than warm receptors
• also activated by menthol
o warm receptor – increase rate of action potential as skin is warmed (25o→47oC)
o comfortable temperature between 25o-35oC → both cold and warm receptors stimulated

Question 10

photoreceptors

Answer 10

detect light

are necessary for vision

Question 11

nociceptors

Answer 11

pain receptors – free naked nerve endings that respond to physical or chemical damage of tissues

Question 12

cutaneous receptors

Answer 12

are associated with the skin

Question 13

free nerve endings

Answer 13

unspecialized neuronal branches similar to dendrites.
• most common and distributed throughout most parts of the body
- These receptors are responsible for a number of sensations, including pain , temp, itch and movement.

Question 14

proprioceptors

Answer 14

information regarding body’s position and movement of parts in space, weight differences, and the extent of stretch or the force of muscular contractions.

Question 15

merkel discs

Answer 15

detect light touch and superficial pressure

Question 16

Hair follicle receptors

Answer 16

detect light touch due to very slight bending of the hair (breeze, bug)

Question 17

Pacinian corpuscles

Answer 17

– deep cutaneous pressure, vibration, proprioception (in joint capsule) = relay information about joint location.

Question 18

Meissner corpuscles

Answer 18

they are distributed throughout the dermal papillae (check it out)
and are involved in 2 points discrimination.

= (fine touch) is the ability to detect simultaneous stimulation of Meissner corpuscles in 2 distinct receptor fields by touching at 2 points on the skin.

• indicates distance between receptive field of two sensory neurons and varies in different areas of the body

ex: They are numerous and close together in the tongue and fingertips but are less numerous and more widely separated in the back.

Question 19

o Ruffini end organs

Answer 19

– detect continuous touch or pressure and responds to depression or stretch of skin
- important in responding to continuous touch or pressure.

Question 20

Muscle spindle

Answer 20

o muscle spindle (Fig 14.4) = 3-10 specialized muscle cells in skeletal muscle innervated with nerve endings
- provide information about length of the muscle.
• detect muscle stretch and rate of stretch
• important in control and tone of skeletal muscle

Question 21

o Golgi tendon organ

Answer 21

afferent associated with the fibres of the tendon near the junction between skeletal muscle and tendon
• respond to increased tendon tension caused either by contraction of the muscle or by passive stretch of the tendon.