Human Anatomy: Nervous System and Cardiovascular System Review

Schwann cells

Form the protective lipid myelin sheath around axons exclusively in the Peripheral Nervous System (PNS).

Oligodendrocytes

Form the myelin sheath around axons exclusively in the Central Nervous System (CNS).

Astrocytes

Star-shaped CNS cells that support neurons, regulate the chemical environment, and form the blood-brain barrier.

Microglia

Specialized CNS macrophages that act as the active immune defense by clearing debris and pathogens.

Dura mater

The tough, fibrous, outermost protective layer anchoring the brain and spinal cord to the skull and vertebral canal.

Pia mater

The delicate, highly vascular innermost layer that adheres directly to the surface of the brain and spinal cord.

Arachnoid mater

The web-like middle layer that sits between the dura mater and the pia mater.

Subarachnoid space

The actual fluid-filled interval beneath the arachnoid mater containing cerebrospinal fluid (CSF).

Precentral gyrus

Located in the frontal lobe; houses the primary motor cortex responsible for controlling voluntary movements.

Postcentral gyrus

Located in the parietal lobe; houses the primary somatosensory cortex responsible for processing bodily sensations like touch and pain.

Occipital lobe

The posterior region of the brain dedicated primarily to processing visual information.

Temporal lobe

The lateral region of the brain responsible for processing auditory input, memory, and language comprehension.

Corpus callosum

The massive white matter tract of commissural fibers that physically connects and transmits data between the left and right cerebral hemispheres.

Thalamus

The egg-shaped structure deep in the brain serving as the main relay station for sensory impulses traveling to the cerebral cortex.

Pons

The middle region of the brainstem that acts as a bridge connecting the cerebellum to the rest of the brainstem and contains respiratory control centers.

Medulla oblongata

The lowest part of the brainstem, continuous with the spinal cord, controlling vital autonomic centers like heart rate and breathing.

Cranial Nerve I - Olfactory

Transmits sensory data regarding the sense of smell from the nasal cavity.

Cranial Nerve II - Optic

Transmits visual sensory data from the retina of the eye to the visual cortex of the brain.

Cranial Nerve III - Oculomotor

Controls voluntary movements of four extrinsic eye muscles, raises the eyelid, and constricts the pupil.

Cranial Nerve V - Trigeminal

The largest cranial nerve; supplies sensory fibers to the face and motor fibers to the muscles of mastication (chewing).

Ventral horn

The anterior gray matter region containing the cell bodies of somatic motor neurons that project to skeletal muscles.

Dorsal horn

The posterior gray matter region where sensory neurons enter the spinal cord and synapse with interneurons.

Lateral horn

The intermediate gray matter region found only in thoracic and lumbar segments, containing cell bodies of autonomic (sympathetic) motor neurons.

Dorsal root ganglion

A cluster of cell bodies belonging to primary sensory (afferent) neurons located just outside the spinal cord gray matter.

Right atrium

Receives low-oxygen, carbon dioxide-rich systemic blood returning from body tissues via the vena cavae.

Right ventricle

Receives deoxygenated blood from the right atrium and pumps it into the pulmonary circuit toward the lungs.

Left atrium

Receives freshly oxygenated blood returning from the lungs via the pulmonary veins.

Left ventricle

Receives oxygenated blood from the left atrium and pumps it under high pressure out to the entire systemic body circuit.

Bicuspid / Mitral valve

The two-cusp atrioventricular (AV) valve preventing blood backflow from the left ventricle into the left atrium.

Tricuspid valve

The three-cusp AV valve preventing blood backflow from the right ventricle into the right atrium.

Aortic semilunar valve

Prevents blood from backflowing from the ascending aorta into the left ventricle.

Pulmonary semilunar valve

Prevents blood from backflowing from the pulmonary trunk into the right ventricle.

Myocardium

The thick, middle layer composed entirely of cardiac muscle tissue responsible for the pumping action of the heart.

Endocardium

The smooth, innermost endothelial lining of the heart chambers and valves.

Epicardium

The visceral layer of the serous pericardium forming the outermost, slippery protective surface of the heart wall.

Parietal pericardium

The outer serous sac lining that forms the protective cavity surrounding the heart.

Chordae tendineae

Tendinous cords ("heart strings") anchoring AV valve cusps to papillary muscles, preventing them from everting during ventricular contraction.

Pectinate muscles

Prominent muscular ridges found lining the inner walls of the atria.

Trabeculae carneae

Irregular muscular ridges and columns lining the internal walls of the ventricles.

Fossa ovalis

An oval depression in the interatrial septum representing the closed remnant of the fetal foramen ovale.

Pulmonary vein

Carries freshly oxygen-rich blood from the lungs into the left atrium of the heart.

Pulmonary artery

Carries oxygen-depleted blood away from the right ventricle into the lungs for gas exchange.

Superior vena cava

Large vein bringing deoxygenated blood from the head, neck, arms, and upper chest back to the right atrium.

Inferior vena cava

Large vein bringing deoxygenated blood from the lower limbs, abdomen, and pelvis back to the right atrium.

Tunica media

The middle blood vessel layer containing smooth muscle tissue and elastic fibers; responsible for regulating blood pressure via vasoconstriction and vasodilation.

Tunica intima

The innermost layer consisting of a single layer of endothelium and a thin basement membrane.

Tunica externa

The outermost connective tissue layer anchoring vessels to surrounding organs.

Endothelium

The simple squamous epithelial cell layer that forms the smooth internal boundary of all blood vessels.

Coronary artery

Branches immediately off the base of the ascending aorta to deliver oxygenated blood directly to the myocardium.

Brachiocephalic artery

The first major branch off the aortic arch; divides into the right subclavian and right common carotid arteries.

Left common carotid artery

The second branch off the aortic arch; ascends up the left side of the neck to supply the head and brain.

Subclavian artery

Branches off to supply blood to the upper extremities (arms) and parts of the thoracic wall.

Capillaries

Microscopic vessels consisting purely of a single layer of endothelial cells to maximize passive diffusion of gases, nutrients, and wastes.

Arterioles

Small arterial branches featuring smooth muscle walls that feed directly into capillary beds and regulate systemic vascular resistance.

Venules

Minute vessels that collect deoxygenated blood exiting capillary networks and drain it into larger veins.

Elastic arteries

Large, thick-walled conduits near the heart (like the aorta) containing massive amounts of elastin to buffer systolic pressure waves.

Sinoatrial (SA) node

The primary anatomical pacemaker of the heart; sets the intrinsic heart rhythm by regularly initiating self-excitatory action potentials.

Atrioventricular (AV) node

Located in the interatrial septum; delays the depolarization impulse briefly to allow the atria to finish contracting before ventricles fire.

Atrioventricular (AV) bundle

Also called the Bundle of His; electrical pathway running down the interventricular septum to distribute signals down toward the apex.