External Nose: The external nose is composed of cartilage and bone, covered by skin, and includes the nostrils and nasal bridge, providing a passage for airflow and supporting olfaction.
Blood Flow Relaxed Ventricles: When the ventricles relax during diastole, blood flows passively from the atria into the ventricles through the open AV valves, preparing the heart for the next contraction.
Kaposis Sarcoma Lesions: Kaposis sarcoma lesions are vascular tumors caused by human herpesvirus 8, often seen in immunocompromised individuals and appearing as purple or dark skin patches.
Catabolic Reactions: Catabolic reactions break down complex molecules into simpler ones, releasing energy often stored as ATP and used for cellular activities.
Embryonic Development of Heart: The heart begins as a simple tube and folds into a four-chambered organ through a series of stages, with beating beginning around week 4 of development.
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.
