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Anatomy & Physiology: Autonomic Nervous System, Endocrine System, and Special Senses

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  • Autonomic Nervous System (ANS)

    Controls involuntary functions such as heart rate, digestion, blood pressure, gland secretion, and smooth muscle activity.

  • Parasympathetic vs Sympathetic Function

    Parasympathetic = Rest and Digest; Sympathetic = Fight or Flight.

  • Origin of Parasympathetic and Sympathetic Divisions

    Parasympathetic originates from craniosacral regions; Sympathetic from thoracolumbar regions of the spinal cord.

  • Neurotransmitters of ANS divisions

    Parasympathetic uses acetylcholine; Sympathetic uses norepinephrine.

  • Effect of Parasympathetic and Sympathetic on Heart Rate

    Parasympathetic decreases heart rate; Sympathetic increases heart rate.

  • Preganglionic vs Postganglionic Neurons

    Preganglionic neuron exits CNS to synapse in autonomic ganglion; Postganglionic neuron extends from ganglion to target organ.

  • Sympathetic Tone

    Baseline sympathetic activity that maintains blood pressure and vessel tone.

  • Vagal Tone

    Parasympathetic influence of the vagus nerve that slows resting heart rate.

  • Somatic vs Autonomic Nervous System

    Somatic controls skeletal muscles voluntarily with one neuron; ANS controls smooth muscle, cardiac muscle, and glands involuntarily with a two-neuron chain.

  • Major Autonomic Plexuses

    Include cardiac, pulmonary, esophageal, celiac (solar), inferior mesenteric, and hypogastric plexuses controlling various organs.

  • Endocrine vs Exocrine Glands

    Endocrine glands secrete hormones into bloodstream without ducts; exocrine glands secrete substances like sweat or enzymes through ducts.

  • Major Hormone Classes

    Steroid hormones (e.g., cortisol), peptide/protein hormones (e.g., insulin), and amine hormones (e.g., epinephrine).

  • Hormone Mechanisms of Action

    Steroid hormones cross membranes and alter gene expression; peptide hormones bind membrane receptors and use second messengers like cAMP.

  • Pituitary Hormones (SeT GAP)

    S: Somatotropin (GH), T: Thyroid Stimulating Hormone (TSH), G: Gonadotropins (FSH/LH), A: Adrenocorticotropic Hormone (ACTH), P: Prolactin (PRL).

  • Posterior Pituitary Hormones

    ADH increases kidney water reabsorption; Oxytocin stimulates uterine contractions and milk ejection.

  • Thyroid Gland Hormones

    Produces T3 and T4 to increase metabolism and calcitonin to decrease blood calcium; iodine is required for synthesis.

  • Parathyroid Hormone (PTH) Function

    Raises blood calcium by stimulating osteoclasts, increasing intestinal absorption, and reducing calcium loss in urine.

  • Adrenal Gland Secretions

    Medulla secretes catecholamines (epinephrine, norepinephrine); cortex secretes corticosteroids including aldosterone and cortisol.

  • Renin-Angiotensin-Aldosterone System (RAAS) Steps

    Low BP → kidney releases renin → renin converts angiotensinogen to angiotensin I → ACE converts to angiotensin II → vasoconstriction and aldosterone release → sodium and water retention.

  • Diabetes Mellitus vs Diabetes Insipidus

    Diabetes mellitus: insulin problems causing hyperglycemia; Diabetes insipidus: ADH deficiency causing excessive urination.

  • Five Special Senses

    Vision, hearing, equilibrium, taste (gustation), and smell (olfaction).

  • Taste Modalities and Cranial Nerves

    Five tastes: sweet, sour, salty, bitter, umami; cranial nerves involved are Facial (VII), Glossopharyngeal (IX), and Vagus (X).

  • Olfaction Receptors and Adaptation

    Located in olfactory epithelium; odorants dissolve in mucus; olfactory adaptation is decreased sensitivity to persistent odors.

  • Photoreceptors in the Eye

    Rods provide night vision; cones provide color vision; fovea centralis has highest cone concentration.

  • Accommodation in Vision

    Lens shape changes to focus on near or far objects.

  • Common Vision Disorders

    Myopia (nearsightedness) corrected with concave lenses; hyperopia (farsightedness) corrected with convex lenses.

  • Visual Pathway

    Cornea → aqueous humor → pupil → lens → vitreous humor → retina → optic nerve → optic chiasm → optic tract → thalamus → visual cortex.

  • Hearing and Balance Receptors

    Mechanoreceptors detect sound and equilibrium; vestibule senses static equilibrium; semicircular canals sense dynamic equilibrium.

  • Sound Pathway

    Auricle → external auditory canal → tympanic membrane → malleus → incus → stapes → oval window → cochlea → organ of Corti → vestibulocochlear nerve → auditory cortex.