TOPIC V: Nervous System III – Integration & Control (Brain + Spinal Cord) Flashcards
What are the two main components of the central nervous
The brain and spinal cord.
What are the roles of the sensory (afferent) and motor (efferent) divisions in relation to the brain and spinal cord?
The sensory division inputs information to the brain and spinal cord, while the motor division controls effectors based on the integrated information.
What are the two main functions of the spinal cord?
To transmit signals to and from the brain and to integrate and execute somatic and autonomic reflexes.
What is a reflex?
A rapid, automatic response to a stimulus that always causes the same motor response and usually serves a protective function.
What are the three ways reflexes are categorized?
By effector (somatic or visceral), location of sensory and motor neurons (ipsilateral or contralateral), and number of synapses in the reflex arc (monosynaptic or polysynaptic).
What is a somatic reflex?
A reflex where the effector is skeletal muscle.
What is a visceral (autonomic) reflex?
A reflex where the effector is smooth muscle, cardiac muscle, or a gland.
What is an ipsilateral reflex?
A reflex where the sensory and motor neurons are on the same side of the body.
What is a contralateral reflex?
A reflex where the sensory and motor neurons are on opposite sides of the body.
What is a monosynaptic reflex?
A reflex arc with one synapse between one sensory and one motor neuron.
What is a polysynaptic reflex?
A reflex arc with two or more synapses between three or more neurons
Describe the stretch reflex.
An automatic muscle contraction in response to sudden stretching that helps maintain muscle tone, stabilize posture and balance, and prevent injury. It is ipsilateral and monosynaptic. Example: knee-jerk reflex.
Describe the flexor (withdrawal) reflex.
Automatic contraction of flexor muscles that moves a body part away from a painful stimulus. Example: Stepping on a nail. It is ipsilateral and polysynaptic.
Describe the crossed extensor reflex.
Automatic contraction of extensor muscles in the opposite limb during a withdrawal reflex. It helps maintain balance. Example: Keeps you from falling when you step on a nail. It is contralateral and polysynaptic.
Describe the micturition reflex.
An autonomic spinal reflex where the stimulus is the stretch of the bladder, leading to contraction of the detrusor muscle and opening of the internal urethral sphincter.
What is reciprocal inhibition?
The inhibition of somatic lower motor neurons to antagonist muscles during contraction of an agonist muscle, ensuring smooth and coordinated movements.
What are the main functions of the cerebrum?
Interpreting sensory information, initiating and controlling skeletal muscle movement, and higher functions like memory, intellect, language, and emotional regulation.
What are the main functions of the brain stem?
Controlling life-sustaining processes such as breathing and circulation.
What are the parts of the brain stem?
Midbrain, pons, and medulla oblongata.
What are the functions of the midbrain?
Auditory and visual reflexes, such as movement of eyes, head, and neck in response to visual/auditory stimuli.
What are the functions of the pons?
Works with the medulla to regulate breathing.
What are the functional regions of the medulla oblongata?
Decussation of sensory and motor tracts, autonomic vital reflex centers (respiratory and cardiovascular), and non-vital areas (swallowing, coughing, sneezing, vomiting).
What are the major functions of the hypothalamus?
Regulates ANS, parts of the endocrine system, temperature, food and water intake, and is part of the limbic system (emotional brain) and reticular activating system (RAS).
