The human brain is capable of unique and complex functions, such as recording history, reasoning, and planning, to a degree unparalleled in the animal kingdom. Many of these functions can only be studied in humans. That is a major reason why much of human brain function remains elusive and why it remains one of the most challenging frontiers of anatomy and physiology.
Sensation, or perception is the conscious awareness of stimuli received by sensory receptors.
Receptors are sensory nerve endings or specialized cells capable of responding to stimuli by developing action potentials.
Receptors include mechanoreceptors, chemoreceptors, photoreceptors, thermoreceptors, and nociceptors.
Free nerve endings detect pain, temperature, itch, and movement (proprioception).
Ascending pathways carry conscious and unconscious sensations. Each pathway carries specific sensory information because each pathway is associated with specific types of receptors.
Sensory Areas of the Cerebral Cortex
1. Sensory pathways project to primary sensory areas (visual, auditory, taste, olfactory, and somatic sensory) in the central cortex.
2. Sensory areas are organized topographically in the somatic sensory cortex.
Association areas of the cerebral cortex process sensory input from the primary sensory areas.
Other Brain Functions
Speech is located only in the left cortex in most people.
Wernicke's area comprehends and formulates speech,
Broca's area receives input from Wernicke's area and sends impulsesto the premotor and motor areas, which causes the muscle movements required for speech.
At least three kinds of memory exist: sensory, short-term, and long-term.
Effects of Aging on the Nervous System
1. There is a general decline in sensory and motor functions as a person ages.
2. Short-term memory is decreased in most older people.
3. Thinking ability does not decrease in most older people.
And that ends our topic about the integration of the nervous system.. Hope you learn something about it..
END of Chapter 12