Integration and Control of Autonomic Functions

Autonomic (Visceral) Reflexes

An automatic motor response, which occur when nerve impulses pass through an autonomic reflex arc, playing an essential role in regulating controlled conditions

Autonomic (Visceral) Reflexes: Blood Pressure

These reflexes help regulate blood pressure by controlling heart rate, ventricular contraction strength, and blood vessel diameter.

Autonomic (Visceral) Reflexes: Blood Pressure

These reflexes help regulate digestion by controlling digestive tract movement and muscle tone.

Autonomic (Visceral) Reflexes: Defecation and Urination

These reflexes help regulate defecation and urination by controlling the opening and closing of sphincters.

Autonomic (Visceral) Reflexes: Sensory Receptor

The receptor in an autonomic reflex arc can be found in the distal end of a sensory neuron, which responds to a stimulus and produce an impulse, similar to receptors in a somatic reflex arc

Autonomic (Visceral) Reflexes: Sensory Receptor: Association

These sensory receptors are associated with interoceptors (which respond to internal stimuli such as stretching of a visceral wall or the chemical composition of a body fluid)

Autonomic (Visceral) Reflexes: Sensory Neurons

Sensory neurons detect internal stimuli like stretch, chemical changes, and pain in organs and transmit these signals from receptors to the CNS

Autonomic (Visceral) Reflexes: Integrating Center

Interneurons relay signals from sensory neurons to motor neurons, with the hypothalamus and brainstem as the main control centers and the spinal cord controlling some autonomic reflexes, such as urination and defecation.

Autonomic (Visceral) Reflexes: Motor Neurons

These reflexes rely on a two-step motor pathway containing a preganglionic neuron and a postganglionic neuron to regulate an effector

Autonomic (Visceral) Reflexes: Motor Neurons: Pathway

The preganglionic neuron conducts motor impulses from the CNS to an autonomic ganglion, and the postganglionic neuron conducts motor impulses from an autonomic ganglion to an effector

Autonomic Nervous System: Skeletal System: Pain

Pain receptors in bone tissue warn of bone trauma or damage.

Autonomic Nervous System: Muscular System: Movement

Somatic motor neurons receive instructions from motor areas of the brain and stimulate skeletal muscle contraction to produce body movements.

Autonomic Nervous System: Muscular System: Muscle Tone

The corpus striatum and reticular formation help set the level of muscle tone.

Autonomic Nervous System: Muscular System: cerebellum

The cerebellum coordinates skilled movements.

Autonomic Nervous System: Endocrine System: Hypothalamus

The hypothalamus regulates the secretion of hormones from the anterior and posterior pituitary.

Autonomic Nervous System: Endocrine System: Suprarenal Medullae

The ANS regulates secretion of hormones from the suprarenal medullae and pancreas.

Autonomic Nervous System: Cardiovascular System: Heart Rate

The cardiovascular center in the medulla oblongata sends nerve impulses to the ANS that regulate heart rate and the forcefulness of the heartbeat.

Autonomic Nervous System: Cardiovascular System: Blood Pressure

The ANS regulates blood pressure and blood flow through blood vessels.

Autonomic Nervous System: Lymphatic System: Immunity

Certain neurotransmitters help regulate immune responses, and nervous system activity may increase or decrease immune responses.

Autonomic Nervous System: Respiratory System: Respiratory Rate

Respiratory areas in the brainstem control breathing rate and depth, while the ANS helps regulate airway diameter.

Autonomic Nervous System: Digestive System: Digestion

Enteric plexuses of the ANS help regulate digestion, and the parasympathetic division stimulates many digestive processes.

Autonomic Nervous System: Urinary System: Kidneys

The ANS helps regulate blood flow to the kidneys and thereby influences urine formation, while brain and spinal cord centers govern emptying of the urinary bladder.

Autonomic Nervous System: Reproductive System: Sexual Behaviors

The hypothalamus and limbic system govern various sexual behaviors, while the ANS produces erection and ejaculation responses.

Autonomic Nervous System: Reproductive System: Genital Regulation

The hypothalamus regulates release of anterior pituitary hormones that control the ovaries and testes.

Autonomic Nervous System: Reproductive System: Lactation

Nerve impulses caused by touch during infant suckling cause oxytocin release and milk ejection in nursing mothers.

Autonomic Nervous System: Integumentary System: Hair and Sweat

Sympathetic nerves control contraction of arrector muscles of the hair and secretion of perspiration from sweat glands.

Hypothalamus: ANS Control

The hypothalamus is the major control and integration center of the autonomic nervous system.

Hypothalamus: Sensory Input

The hypothalamus receives sensory information (smell, taste, temperature, osmolarity, and levels of various substances in the blood) and emotions from the limbic system

Hypothalamus: Autonomic Output

Output from the hypothalamus influences autonomic centers in the brainstem (such as the cardiovascular, salivation, swallowing, and vomiting centers) and the spinal cord (such as the defecation and urination reflex centers)

Hypothalamus: ANS Connections

The hypothalamus is connected to both the sympathetic and parasympathetic divisions by axons from neurons in various hypothalamic nuclei.

Hypothalamus: Reticular Formation

Axons from the hypothalamus reach sympathetic and parasympathetic nuclei in the brainstem and spinal cord through relays in the reticular formation.

Hypothalamus: Sympathetic Control

The posterior and lateral hypothalamic regions control the sympathetic division, where stimulation of these areas increases heart rate, force of contraction, blood pressure, body temperature, dilates pupils, and inhibits the digestive canal.

Hypothalamus: Parasympathetic Control

The anterior and medial hypothalamic regions control the parasympathetic division, where stimulation of these areas decreases heart rate and blood pressure, constricts pupils, and increase secretion and motility of the gastrointestinal tract.

Hypothalamus: Sympathetic vs. Parasympathetic

The posterior and lateral hypothalamus promote sympathetic activity, while the anterior and medial hypothalamus promote parasympathetic activity.