The Trachea: The trachea, or windpipe, is a rigid tube reinforced with C-shaped cartilage rings that conducts air from the larynx to the bronchi while keeping the airway open.
Aquaporin Water Channel: Aquaporins are membrane proteins that facilitate rapid water transport across cell membranes, essential for maintaining fluid balance in tissues like the kidneys and the brain.
Phases of the Cardiac Cycle: The cardiac cycle includes atrial systole, ventricular systole, and diastole, each phase coordinating contraction and relaxation to maintain continuous blood flow through the heart and circulatory system.
Germ Layers: The three primary germ layersectoderm, mesoderm, and endodermform during gastrulation and give rise to all tissues and organs in the developing embryo.
Goiter: A goiter is an abnormal enlargement of the thyroid gland, often due to iodine deficiency, autoimmune disease, or hormonal imbalance, which can lead to visible swelling in the neck and thyroid dysfunction.
Chordae Tendinae Papillary Muscles: These structures work together to prevent prolapse of the heart valves during ventricular contraction; the chordae tendineae anchor the valve cusps to the papillary muscles in the ventricles.
Capillary Bed: Capillary beds are networks of microscopic vessels where exchange of oxygen, nutrients, and waste occurs between blood and surrounding tissues, regulated by precapillary sphincters that control blood flow.
Major Systematic Veins: Major systemic veins include the superior and inferior vena cava, jugular veins, subclavian veins, and iliac veins, all channeling deoxygenated blood back to the heart.
Large Intestine: The large intestine absorbs water and electrolytes from indigestible food matter and forms and stores feces, while also housing beneficial bacteria that aid in digestion and vitamin production.
Heart Musculature: The heart is composed of specialized cardiac muscle tissue known as myocardium, which contracts rhythmically and involuntarily to pump blood through the circulatory system.
Depolarization in Sinus Rhythm: In normal sinus rhythm, depolarization originates in the SA node and spreads uniformly through the atria and ventricles, resulting in coordinated heartbeats seen as distinct P, QRS, and T waves on an ECG.
The Absorptive Stage: During the absorptive stage, which occurs while nutrients are being digested and absorbed, the body uses glucose as its primary energy source and stores excess nutrients as glycogen and fat under the influence of insulin.
Renin Angiotensin Aldosterone Pathway: This hormonal cascade begins with renin release from the kidneys, leading to the formation of angiotensin II, a potent vasoconstrictor, and the secretion of aldosterone, which promotes sodium and water retention.
Major Systemic Artery: The major systemic artery is the aorta, which distributes oxygenated blood from the left ventricle to the entire body via its ascending, arch, and descending sections.
Human Heart Photo: A detailed photo of the human heart shows its four chambers, major vessels, and coronary arteries, often labeled for anatomical study or medical education.
The Anterior Pituitary Complex: The anterior pituitary produces hormones including ACTH, TSH, GH, FSH, LH, and prolactin, regulated by hypothalamic signals and responsible for growth, metabolism, and reproductive function.
Comparison of Artery and Vein: Arteries have thick, muscular walls to handle high pressure and carry blood away from the heart, while veins have thinner walls, valves, and carry blood back to the heart under lower pressure.
Sewage Treatment Plan: A sewage treatment plant uses a combination of physical, chemical, and biological processes to remove contaminants from wastewater, producing treated water safe for discharge or reuse and minimizing environmental impact.
The Respiratory Zone: The respiratory zone includes respiratory bronchioles, alveolar ducts, and alveoli, where gas exchange occurs between air and pulmonary capillary blood.
Large Medium Vein Venule: Venous return involves small venules merging into medium and large veins; these vessels have thinner walls than arteries and contain valves to prevent backflow.