Endocrine System, Blood Formed Elements, and Immunohematology

Vocabulary flashcards covering endocrine structures, hormones, blood formed elements, and immunohematology concepts.

Adrenal medulla

The inner region of the adrenal gland containing medullary chromaffin cells that secretes catecholamines, specifically epinephrine and norepinephrine.

Adrenal cortex

The outer region of the adrenal gland consisting of the zona glomerulosa, zona fasciculata, and zona reticularis, which secretes mineralocorticoids, glucocorticoids, and gonadocorticoids.

Zona glomerulosa

The outermost layer of the adrenal cortex responsible for secreting mineralocorticoids, specifically aldosterone.

Zona fasciculata

The middle layer of the adrenal cortex responsible for secreting glucocorticoids, specifically cortisol.

Zona reticularis

The innermost layer of the adrenal cortex responsible for secreting gonadocorticoids, specifically androgens and estrogens.

Thymic (Hassall’s) corpuscles

Microscopic structures located in the medulla of the thymus, an organ that is larger during childhood and involved in T cell development.

Formed Elements

The cellular components of blood, which include red blood cells (erythrocytes), platelets (thrombocytes), and white blood cells (leukocytes).

Plasma

The liquid component of blood consisting of water and proteins.

Granulocytes

A group of white blood cells containing visible granules, comprising neutrophils, eosinophils, and basophils.

Agranulocytes

A group of white blood cells lacking visible granules, comprising lymphocytes and monocytes.

Erythrocytes

Red blood cells that carry antigens (agglutinogens) on their membrane and lack nuclei.

Thrombocytes

Platelets, which are formed elements of the blood.

Leukocytes

White blood cells, divided into granulocytes and agranulocytes, responsible for immune responses.

Neutrophils

The most common leukocyte, making up $50\text{--}70\text{\%}$ of white blood cells, featuring a multi-lobed nucleus and acting as phagocytes to fight bacteria.

Eosinophils

Granulocytes with bi-lobed nuclei that make up $2\text{--}4\text{\%}$ of white blood cells, fighting parasites and decreasing inflammation.

Basophils

Granulocytes with a peanut-like appearance that make up $< 1\text{\%}$ of white blood cells, releasing histamine to increase inflammation during allergic reactions.

Monocytes

The largest type of white blood cell, making up $2\text{--}8\text{\%}$ of leukocytes.

Lymphocytes

Agranulocytes making up $20\text{--}30\text{\%}$ of leukocytes, including T cells and B cells that mediate viral immunity.

Agglutinogens

Antigens located on the red blood cell membrane that determine blood type.

Agglutinins

Antibodies located in the blood plasma that target non-self antigens.

Hypothalamus

An endocrine structure that secretes regulatory hormones, antidiuretic hormone (ADH), and oxytocin.

Adenohypophysis

The anterior pituitary gland, which secretes tropic hormones (FSH, LH, ACTH, TSH) and non-tropic hormones (GH, PRL).

Neurohypophysis

The posterior pituitary gland, which releases oxytocin (OT) and antidiuretic hormone (ADH).

Pineal gland

An endocrine gland responsible for secreting melatonin.

Thyroid gland

An endocrine gland composed of thyroid follicles and parafollicular cells that secretes thyroid hormone (T3 and T4) and calcitonin.

Colloid

The substance inside the thyroid follicle space surrounded by cuboidal follicle cells that secretes thyroid hormone.

Parathyroid glands

Endocrine glands containing chief (principal) cells and oxyphil cells that produce parathyroid hormone (PTH).

Medullary chromaffin cells

Specific cells in the adrenal medulla that secrete epinephrine and norepinephrine.

Pancreatic acini

Exocrine tissue structures in the pancreas surrounding the endocrine islets.

Islet of Langerhans

Microscopic endocrine clusters in the pancreas that secrete insulin and glucagon.