Autonomic Nervous System and Endocrine System Review Notes

Autonomic Nervous System (ANS) and Endocrine System Review

Autonomic Nervous System Functions

• The autonomic nervous system (ANS) controls respiratory functions during rest and activity.

Somatic vs. Autonomic Nervous System

• Somatic Nervous System: Lower motor neurons exert direct control over skeletal muscles.
• Autonomic Nervous System:
  • Features a synapse between the CNS and the peripheral effector.
  • Involves indirect control.

Parasympathetic Nervous System Functions

• Functions Include:
  • Changes in blood flow and glandular activity associated with sexual arousal.
  • Constriction of respiratory passages.
  • Increased secretion of hormones promoting nutrient absorption and utilization by peripheral cells.
• Does NOT include:
  • Mobilization of energy reserves through accelerated breakdown of glycogen and release of lipids.

System Coordination

• The autonomic nervous system (ANS) coordinates cardiovascular, respiratory, digestive, urinary, and reproductive functions.

Divisions of the Nervous System

• Sympathetic Division: "Kicks in" during periods of exertion, stress, or emergency.

Sympathetic Chain Ganglion

• White Ramus: Nerve bundle that carries preganglionic fibers to a nearby sympathetic chain ganglion.

Autonomic Nerves in the Thoracic Cavity

• Functions of postganglionic fibers:
  • Dilating the respiratory passageways.
  • Accelerating the heart rate.
  • Increasing the force of cardiac contractions.

Modified Neurons in the Sympathetic Division

• The effects of neurotransmitters secreted last longer than those produced by direct sympathetic stimulation.
• Serve to dilate blood vessels and elevate blood pressure

Neurotransmitter Effects

• Stimulation or inhibition of activity depends on the response of the membrane receptor to the presence of the neurotransmitter.

Cholinergic Postganglionic Sympathetic Fibers

• During exercise, stimulation of these fibers innervating sweat glands and blood vessels of skeletal muscles helps to keep the body cool and provide oxygen/nutrients to active muscles.

Sympathetic Nervous System Synapses

• Postsynaptic cells synapse with innervated cells through structures called varicosities.

Parasympathetic Division Neurons

• Second-order neurons originate in intramural ganglia or ganglia associated with the target organs.

Parasympathetic Neurotransmitter

• Acetylcholine (ACh) is released by all parasympathetic neurons.

Parasympathetic Receptors

• The two types of parasympathetic receptors on postsynaptic membranes are nicotinic and muscarinic.

Pelvic Nerves

• Carry parasympathetic neurons innervating the urinary bladder.

Major Effects of Parasympathetic Division

• Secretion by digestive glands.
• Constriction of the respiratory passageway.
• Increased smooth muscle activity along the digestive tract.

Autonomic Nervous System Divisions

• The parasympathetic division innervates only visceral structures serviced by the cranial nerves or nerves within the abdominopelvic cavity.

Dual Innervation

• Where dual innervation exists, the two divisions of the ANS commonly have opposing effects.

Autonomic Tone

• Important because it allows for an increase or decrease of activity, providing a greater range of control.

Coordination and Regulation of Sympathetic Function

• Generally occur in centers in the medulla oblongata and spinal cord.

Autonomic Reflexes

• Simple reflexes providing rapid automatic responses are based in the spinal cord.

Visceral Reflex Processing Center

• The processing center of a visceral reflex is the interneuron.

Long Reflexes

• FALSE statement: They bypass the central nervous system (CNS).

Visceral Reflexes Provide

• Automatic motor responses.

Limbic System Components for Memory Consolidation

• The amygdaloid body and hippocampus.

Consciousness

• A state of awareness of and attention to external events and stimuli.

Reticular Activating System (RAS)

• Increasing stimulation to the RAS makes an individual more alert to sensory information.

Neurotransmitter Disturbance in Parkinson's Disease

• Disturbance of dopamine produces motor problems.

Aging and the Nervous System

• Plaques are an accumulation of extracellular fibrillar proteins and abnormal dendrites and axons.

Postganglionic Fiber

• The axon of a ganglionic neuron is called a postganglionic fiber because:
  • It carries impulses away from the ganglion
  • It carries impulses to the target organ.

Effects of Sympathetic Postganglionic Fibers in Spinal Nerves

• Acceleration of blood flow to skeletal muscles.
• Stimulation of secretion by sweat glands.
• Dilation of the pupils and focusing of the eyes.

Collateral Ganglia Summary Effects

• Redirection of blood flow and energy use by visceral organs and release of stored energy.

Alpha-1 Receptor Stimulation

• Triggers a depolarization that has an excitatory effect.

Structural Difference Between Sympathetic Fibers

• Preganglionic fibers are short, and postganglionic fibers are long.

Adrenergic Receptors Producing Stimulatory Effects

• Beta-1 stimulates metabolism and energy consumption.

Effects of Parasympathetic Stimulation

• Brief in duration and restricted to specific organs and sites.

Beta Receptor Blockers and Blood Pressure

• Beta-1 receptors in the heart do not stimulate an increase in the force and rate of heart contractions.

Crisis Response

• Sympathetic activation is necessary to cope with stressful situations.

Classes of Sympathetic Receptors

• Alpha and beta receptors.

Intramural Ganglia Location

• Inside the tissues of visceral organs.

Vagus Nerve and Abdominopelvic Cavity

• Parasympathetic preganglionic fibers of the vagus nerve entering the abdominopelvic cavity join the celiac plexus.

Sensory Nerve Information Delivery

• Delivers information to the CNS along spinal nerves, cranial nerves, and autonomic nerves that innervate peripheral effectors.

Sympathetic Reflexes

• Cardioacceleratory, vasomotor, pupillary, and ejaculation reflexes.

Endocrine System Review

Endocrine System Response Patterns

• Particularly effective in coordinating cell tissue and organ activities on a sustained long-term basis.

Endocrine-Controlled Processes

• NOT an endocrine-controlled process:
  • The constriction of the iris muscles when a bright light is shined on the eye

Hormone Release Effects

• Alters the metabolic activities of many tissues and organs simultaneously.

Biogenic Amino Hormones

• E, NE, dopamine, melatonin, and thyroid hormones

Non-Amino Acid Derivative Hormone

• Eicosanoids

Hormone Action

• A hormone that stimulates the opening of calcium channels and interaction with calmodulin will trigger the activation of cytoplasmic enzymes.

Melanocyte-Stimulating Hormone

• Secreted in the pituitary gland and controls melanin production during fetal development, in young children, in pregnant women, and in some disease states.

Hypothalamus as a Control Center

• Initiates endocrine and neural reflexes
• Contains autonomic centers and acts as an endocrine organ.

Pituitary Gland Location

• Encased in the sella turcica.

Pituitary Gland Connection to Hypothalamus

• Connected via the infundibulum.

Low Gonadotropin Production

• Produces a condition called hypogonadism.

Thyroid Gland Location

• Curves across the anterior surface of the trachea just inferior to the thyroid cartilage.

Effects of Thyroid Hormones on Peripheral Tissues

• Elevating levels of oxygen consumption and energy consumption.
• Maturation of lymphocytes
• Increasing heart rate and force of contraction.
• Stimulation of the formation of red blood cells.

Causes of Hypothyroidism

• Inadequate dietary iodide.

Location of Parathyroid Glands

• Embedded in the posterior surfaces of the thyroid glands.

Adrenal Gland Secretions

• Endocrine secretions from the zona glomerulosa would increase levels of sodium ions retained at the kidney.

Hormones Released by Adrenal Medulla

• Epinephrine and norepinephrine.

Abnormal Glucocorticoid Production

• Results in Addison disease and Cushing disease.

Pancreas Location

• Lies in the J-shaped loop between the stomach and the small intestine in the abdominopelvic cavity.

Pancreatic Hormones

• Insulin and glucagon regulate blood glucose concentrations.

ANP Effects

• Decreases thirst.

Hormone Released From Adipose Tissue

• Leptin causes a sense of fullness and satiety.

Hormone Effects

• The additive effects of growth hormone (GH) and glucocorticoids illustrate the synergistic effect.
• The differing but complementary effects of calcitriol and parathyroid hormone on tissues involved in calcium metabolism illustrate the integrative effect.

Insulin's Importance to Normal Growth

• Providing adequate amounts of energy and nutrients to growing cells.

Pancreatic Cell Producing Glucagon

• Alpha cell.

Thyroid Hormone with Four Iodine Ions

• Thyroxine.

Parathyroid Gland Cells Secreting Parathormone

• Chief cells (aka principal cells).

Hormones Important for Normal Growth

• GH, thyroid hormones, insulin, PTH, and reproductive hormones.

Hormone Secretions

• All the hormones secreted by the hypothalamus, pituitary gland, heart, kidneys, adipose, digestive tract, and pancreas are peptide hormones.

Peptide Hormone Action

• The binding of a peptide hormone to its receptor starts a biochemical chain of events that changes the pattern of enzymatic activity within the cell.

Hypothalamus and Endocrine Functions

• The hypothalamus has a profound effect on endocrine functions through the secretion of releasing and inhibiting hormones.

Pituitary Endocrine Cell Stimulation

• A pituitary endocrine cell that is stimulated by a releasing hormone is usually inhibited by the peripheral hormone it controls.

Pancreatic Acini Function

• Secrete large quantities of an alkaline, enzyme-rich fluid used to digest materials in the duodenum.

Renin Release

• Does NOT Stimulate renin release from kidneys:
  • parasympathetic stimulation

FSH in Males

• Maturation of germinative cells in the gonads.

Prolactin's Involvement

• Production of milk.

Epinephrine's Effects

• Increased cardiac activity.
• Glycogen breakdown.
• Release of lipids by adipose tissues.

Cushing Disease Cause

• Secretions from the zona fasciculata of the adrenal cortex.

Glucocorticoid Production

• Produced and secreted by the cortex of the adrenal glands.

Kidney and Heart Endocrine Functions

• Erythropoietin and atrial natriuretic peptide.

Male Reproductive System Hormones

• Inhibin and testosterone.

Female Reproductive System Hormones

• Estrogens, inhibin, and progesterone.

Non-Growth Hormone Disorder

• Cushing's disease.

Effects of Hormones on the CNS

• Changes in the mixtures of hormones reaching the CNS can have significant effects on:
  • Intellectual capabilities
  • Emotional states
  • Memory and learning