Exam 2 Study Guide: Nervous System, Special Senses, and Endocrine System

Chapter 7: The Nervous System

Overview of the Nervous System

The nervous system is the body's primary communication and control center, responsible for integrating sensory input and coordinating motor output. It is divided into the central nervous system (CNS) and peripheral nervous system (PNS).

• Central Nervous System (CNS): Consists of the brain and spinal cord; processes information and determines responses.

• Peripheral Nervous System (PNS): Composed of nerves outside the CNS; transmits signals between the CNS and the rest of the body.

Somatic vs. Autonomic Nervous Systems

• Somatic Nervous System (SNS): Controls voluntary movements of skeletal muscles.

• Autonomic Nervous System (ANS): Regulates involuntary functions (e.g., heart rate, digestion).

Comparison Table:

Feature	Somatic NS	Autonomic NS
Control	Voluntary	Involuntary
Effector Organs	Skeletal muscles	Cardiac/smooth muscle, glands
Neurotransmitter	Acetylcholine	Acetylcholine, norepinephrine

Sympathetic vs. Parasympathetic Divisions of the ANS

• Sympathetic Division: Prepares the body for 'fight or flight' (increases heart rate, dilates pupils, inhibits digestion).

• Parasympathetic Division: Promotes 'rest and digest' (slows heart rate, stimulates digestion, constricts pupils).

Meninges and Cerebrospinal Fluid (CSF)

• Meninges: Three protective membranes surrounding the CNS:

  • Dura mater: Tough, outermost layer.

  • Arachnoid mater: Web-like middle layer.

  • Pia mater: Thin, inner layer adhering to the brain and spinal cord.

• Cerebrospinal Fluid (CSF): Cushions the brain, removes waste, and circulates nutrients.

Major Parts of the Brain and Their Functions

• Cerebrum: Higher brain functions (thought, memory, voluntary movement).

• Cerebellum: Coordination and balance.

• Brainstem: Controls vital functions (breathing, heart rate).

• Diencephalon: Includes thalamus (sensory relay) and hypothalamus (homeostasis, hormone regulation).

Neuroglia (Glial Cells) of the CNS

• Astrocytes: Support neurons, maintain blood-brain barrier.

• Oligodendrocytes: Produce myelin in the CNS.

• Microglia: Act as immune cells, remove debris.

• Ependymal Cells: Line ventricles, produce and circulate CSF.

Pathway of Sensory and Motor Nerve Impulses

• Sensory Pathway: Free nerve endings detect stimulus → sensory neuron → CNS.

• Motor Pathway: CNS → motor neuron → effector (muscle/gland).

Myelinated vs. Unmyelinated Nerves

• Myelinated Nerves: Have a myelin sheath, allowing faster impulse conduction via nodes of Ranvier (saltatory conduction).

• Unmyelinated Nerves: Lack myelin, conduct impulses more slowly.

• Myelin-Producing Cells: Oligodendrocytes (CNS), Schwann cells (PNS).

Neurotransmitters and Nerve Transmission

• Neurotransmitters: Chemical messengers released from neurons to transmit signals across synapses.

• Function: Bind to receptors on the postsynaptic cell, initiating or inhibiting an action potential.

Cranial Nerves

There are 12 pairs of cranial nerves, each with a specific number, name, classification, and general function.

Number	Name	Type	General Function
I	Olfactory	Sensory	Smell
II	Optic	Sensory	Vision
III	Oculomotor	Motor	Eye movement, pupil constriction
IV	Trochlear	Motor	Eye movement
V	Trigeminal	Both	Facial sensation, chewing
VI	Abducens	Motor	Eye movement
VII	Facial	Both	Facial expression, taste
VIII	Vestibulocochlear	Sensory	Hearing, balance
IX	Glossopharyngeal	Both	Taste, swallowing
X	Vagus	Both	Viscera control, taste
XI	Accessory	Motor	Head/shoulder movement
XII	Hypoglossal	Motor	Tongue movement

Chapter 8: Special Senses

Anatomy of the Eye

• External Structures: Eyelids, eyelashes, conjunctiva, lacrimal apparatus.

• Internal Structures: Sclera, cornea, choroid, retina, lens, iris, pupil.

Layers of the Eyeball

• Fibrous Layer: Sclera (white), cornea (transparent front).

• Vascular Layer: Choroid (blood supply), ciliary body, iris.

• Sensory Layer: Retina (contains photoreceptors).

Pathway of Light Through the Eye

• Light passes through: cornea → aqueous humor → pupil → lens → vitreous humor → retina.

• Function: Each structure refracts or focuses light to form a clear image on the retina.

Anatomy of the Ear

• External Ear: Auricle (pinna), external auditory canal.

• Middle Ear: Tympanic membrane (eardrum), ossicles (malleus, incus, stapes), auditory tube.

• Inner Ear: Cochlea (hearing), vestibule and semicircular canals (balance).

Glaucoma vs. Cataracts

Condition	Description
Glaucoma	Increased intraocular pressure damages optic nerve; can lead to vision loss.
Cataracts	Clouding of the lens, causing blurred vision.

Chapter 9: The Endocrine System

Endocrine Organs and Glands

• Major Glands: Pituitary, thyroid, parathyroid, adrenal, pancreas, pineal, thymus, gonads.

• Location: Scattered throughout the body; each gland secretes specific hormones into the bloodstream.

Stimuli for Hormone Release

• Humoral Stimulus: Changes in blood levels of ions/nutrients trigger hormone release (e.g., blood calcium).

• Hormonal Stimulus: Hormones stimulate other glands to release hormones (e.g., pituitary hormones).

• Neural Stimulus: Nerve fibers stimulate hormone release (e.g., adrenal medulla).

Pancreatic Hormones: Insulin and Glucagon

• Insulin: Lowers blood glucose by promoting cellular uptake and storage as glycogen.

• Glucagon: Raises blood glucose by stimulating glycogen breakdown in the liver.

The Stress Response

• General Adaptation Syndrome: Body's response to stress involves the hypothalamus, pituitary, and adrenal glands (HPA axis).

• Hormones Involved: Cortisol, epinephrine, norepinephrine.

Hormones of Major Endocrine Glands

Gland	Hormone	Function
Adrenal Cortex	Glucocorticoids (cortisol/cortisone)	Regulate metabolism, stress response
Adrenal Cortex	Mineralocorticoids (aldosterone)	Regulate sodium and potassium balance
Adrenal Medulla	Epinephrine, Norepinephrine	Fight or flight response
Hypothalamus	Releasing/inhibiting hormones	Regulate pituitary gland
Pancreas	Insulin, Glucagon	Regulate blood glucose
Parathyroid	Parathyroid hormone (PTH)	Increases blood calcium
Pituitary (anterior)	ACTH, TSH	Stimulate adrenal cortex, thyroid gland
Pituitary (posterior)	ADH	Water retention by kidneys
Thyroid	Thyroxine (T4), Triiodothyronine (T3), Calcitonin	Regulate metabolism, lower blood calcium

Key Hormones: Location, Role, and Function

• ACTH (Adrenocorticotropic Hormone): Anterior pituitary; stimulates adrenal cortex to release cortisol.

• TSH (Thyroid Stimulating Hormone): Anterior pituitary; stimulates thyroid gland to produce T3 and T4.

• Glucocorticoids (Cortisol/Cortisone): Adrenal cortex; regulate metabolism, stress response.

• Mineralocorticoids (Aldosterone): Adrenal cortex; regulate sodium and potassium balance.

• ADH (Antidiuretic Hormone): Posterior pituitary; promotes water reabsorption in kidneys.

• PTH (Parathyroid Hormone): Parathyroid; increases blood calcium levels.

• Thyroxine (T4) & Triiodothyronine (T3): Thyroid; regulate metabolism.

• Calcitonin: Thyroid; lowers blood calcium levels.

• Epinephrine & Norepinephrine: Adrenal medulla; mediate fight or flight response.

• Insulin & Glucagon: Pancreas; regulate blood glucose levels.

Additional info: For exam preparation, focus on understanding the structure, function, and interrelationships of these systems, as well as the mechanisms of hormone action and neural signaling.