LAB PRACTICAL 1

Endocrine System

A system that releases hormones into the bloodstream to regulate physiological events throughout the body.

Hormones

Chemical messengers released by ductless endocrine glands.

Neuroendocrine Organs

Endocrine organs made of nervous tissue that release neurohormones.

Humoral Control

Hormones are released in response to the concentration of certain substances in the blood.

Neural Control

Hormones are released in response to electrical impulses.

Hormonal Control

Hormones are released in response to other hormones.

Hormone Imbalance

Condition that arises when a gland produces too little or too much of a hormone.

Feedback Mechanisms

Processes that correct hormone imbalances.

Hypothalamus

Major homeostatic organ that regulates blood pressure, hunger, thirst, body temperature, and reproductive functions.

Anterior Pituitary Gland

Part of the pituitary gland composed of epithelial tissue, releases hormones like FSH and LH.

Melatonin

Hormone secreted by the pineal gland that controls the sleep/wake cycle.

Thymosin and Thymopoietin

Hormones produced by the thymus that contribute to the maturation of T-lymphocytes.

Thyroid Hormones

Hormones, including T3 and T4, regulate metabolic rate and thermoregulation.

Parathyroid Hormone (PTH)

Hormone that increases blood calcium levels by targeting bones, kidneys, and small intestine.

Adrenal Cortex

Outer region of the adrenal glands that produces steroid hormones.

Glucocorticoids

Steroid hormones that regulate glucose metabolism.

Insulin

Hormone secreted by Beta cells in the pancreas that lowers blood glucose levels.

Gametes

Sex cells produced by testes (sperm) and ovaries (oocytes).

Formed Elements

Components of blood, including red blood cells, white blood cells, and platelets.

Hemodynamics

The physiology of blood flow.

Erythrocytes

Mature red blood cells that transport oxygen and carbon dioxide.

Leukocytes

White blood cells that play a role in the immune response.

Platelets

Cell fragments that mediate blood clotting during hemostasis.

Coagulation

The process that leads to blood clotting.

Hematocrit

Percentage of erythrocytes in a volume of blood.

Pericardium

Double-layered membrane surrounding the heart.

Atria

The superior thin-walled chambers of the heart that receive blood.

Ventricles

The inferior thick-walled chambers of the heart that pump blood.

Tricuspid Valve

Valve that prevents backflow of blood from the right ventricle to the right atrium.

Mitral Valve

Valve that prevents backflow of blood from the left ventricle to the left atrium.

Great Vessels

The largest blood vessels of the body that carry blood to and from the heart.

Systemic Circuit

Pathway through which oxygenated blood is pumped from the left ventricle to the body.

Coronary Circulation

Supplies oxygen and nutrients to the heart muscle.

Coronary Sinus

Vein that drains the myocardium into the right atrium.

Neuroendocrine Organs

Endocrine organs made of nervous tissue whose primary function is to release neurohormones into the bloodstream.

Humoral Control

Hormone release stimulated in response to changing blood concentrations of specific substances, such as glucose or calcium ions.

Neural Control

Hormone release stimulated in direct response to electrical impulses.

Hormonal Control

Hormone release stimulated in response to other hormones.

Hypothalamus

Major homeostatic organ in the diencephalon that regulates blood pressure, body temperature, hunger, thirst, and releases hypothalamic hormones.

Pituitary Gland

Gland sitting in the sphenoid bone consisting of an anterior epithelial lobe (adenohypophysis) and a posterior nervous lobe (neurohypophysis).

Melatonin

Hormone secreted by the pineal gland that controls sleep-wake cycles (circadian rhythms).

Calcitonin

Hormone secreted by parafollicular cells of the thyroid gland that lowers blood calcium levels.

Parathyroid Hormone (PTH)

Hormone that elevates blood calcium levels by targeting bones, kidneys, and the small intestine, stimulating osteoclasts to break down bone.

Zona Glomerulosa

Outer layer of the adrenal cortex that produces mineralocorticoids (mainly aldosterone) to regulate mineral balance and blood pressure.

Zona Fasciculata

Middle layer of the adrenal cortex producing glucocorticoids (mainly cortisol) to regulate glucose metabolism.

Zona Reticularis

Inner layer of the adrenal cortex producing glucocorticoids and androgenic steroids.

Pancreatic Islets

Hormone-producing endocrine clusters in the pancreas containing Alpha cells (glucagon), Beta cells (insulin), and Delta cells (somatostatin).

Erythrocytes

Anucleate, biconcave red blood cells filled with hemoglobin for gas transport.

Granulocytes

White blood cells containing cytoplasmic granules; includes neutrophils, eosinophils, and basophils.

Agranulocytes

White blood cells lacking brightly staining granules; includes lymphocytes and monocytes.

Platelets (Thrombocytes)

Cell fragments of megakaryocytes in red bone marrow that mediate blood clotting (coagulation).

Hematocrit

The percentage of total blood volume occupied by erythrocytes.

Type O- Blood

Blood type lacking A, B, and Rh antigens, making it the universal donor.

Type AB+ Blood

Blood type expressing A, B, and Rh antigens, making it the universal recipient.

Pericardium

Double-layered membrane surrounding the heart consisting of an outer fibrous layer and an inner serous layer.

Myocardium

Middle layer of the heart wall composed primarily of cardiac muscle tissue.

Sinoatrial (SA) Node

The pacemaker of the heart located in the right atrium that initiates action potentials.

QRS Complex

Deflection on an ECG representing ventricular depolarization (which masks atrial repolarization).

Tunica Media

Middle layer of a blood vessel wall composed of smooth muscle and elastic fibers, regulated by the sympathetic nervous system.