Kaplan MCAT Behavioral Sciences Review, Chapter 1, Lesson 2. Organization of the Human Nervous System

Kaplan MCAT Behavioral Sciences Review, Chapter 1, Lesson 2. Organization of the Human Nervous System

Over 100 billion

Number of cells in the human nervous system

Sensory neurons / Afferent neurons

Neurons which transmit sensory information from receptors to the spinal cord and brain

Motor neurons / Efferent neurons

Neurons which transmit motor information from the brain and spinal cord to muscles and glands

Interneurons

The most common type of neuron. They are found between other neurons that are located predominantly in the brain and spinal cord, and which are often linked to reflexive behavior.

Reflex arc

An automatic pathway that acts using an interneuron in the spinal cord before sending the sensory information all the way up to the brain.

Central nervous system

The region of the nervous system composed of the brain and the spinal cord

Peripheral nervous system

The region of the nervous system made up of nerve tissue and fibers outside the brain and spinal cord.

Spinal nerves

Nerves emanating from the spinal cord

Cranial nerves

Nerves emanating directly from the brain

31

Number of pairs of spinal nerves

12

Number of pairs of cranial nerves

PNS

Which branch of the nervous system are the spinal nerves and cranial nerves a part of? (Type "PNS" or "CNS")

Somatic nervous system

The part of the peripheral nervous system which consists of sensory and motor neurons distributed throughout the skin, joints, and muscles.

Autonomic nervous system

The part of the peripheral nervous system that regulates heartbeat, respiration, digestion, and glandular secretions.

Parasympathetic nervous system

The role of this branch of the autonomic nervous system is to conserve energy. It is associated with resting and sleeping states, it reduces heart rate, and it constricts the bronchi. It also manages digestion by increasing peristalsis and exocrine secretions.

Acetylcholine

The neurotransmitter responsible for parasympathetic responses in the body.

Sympathetic nervous system

The branch of the autonomic nervous system activated by stress. It increases heart rate, redistributes blood to muscles of locomotion, increases blood glucose concentration, relaxes the bronchi, decreases digestion, and dilates the eyes to maximize light intake.

Epinephrine

What does the sympathetic nervous system release into the bloodstream?