Human Anatomy: Endocrine System

Flashcards testing concepts of the endocrine system including pituitary, thyroid, adrenal, and pancreatic anatomy and physiology based on the lecture notes.

How do endocrine glands release their chemical secretions into the body?

Endocrine glands are ductless; they secrete hormones into tissue fluids and then into the bloodstream.

What are the two major categories of hormones based on chemical structure?

1. Peptide hormones (includes proteins, glycoproteins, and modified amino acids).
2. Steroid hormones (lipids with the same base structure but differing side chains).

How does the hypothalamus regulate the internal environment through the autonomic nervous system?

It regulates heart rate, body temperature, and water balance.

What are the two anatomical subdivisions of the pituitary gland (hypophysis)?

1. Posterior pituitary gland (neurohypophysis).
2. Anterior pituitary gland (adenohypophysis).

What are the three distinct anatomical areas of the anterior pituitary (adenohypophysis)?

Pars distalis, pars intermedia, and pars tuberalis.

Where are antidiuretic hormone (ADH) and oxytocin synthesized, and where are they stored?

They are produced by neurosecretory cells in the hypothalamus and stored in the posterior pituitary gland.

What are the primary physiological actions of antidiuretic hormone (ADH, or vasopressin)?

It increases water reabsorption in the kidneys and raises blood pressure via vasoconstriction when blood salt concentration is high.

What medical condition results from an inability to produce ADH?

Diabetes insipidus.

What are the main functions of oxytocin during childbirth and nursing?

Oxytocin causes uterine contractions during childbirth and milk letdown (ejection) when a baby is nursing.

What pattern defines the portal system connecting the hypothalamus and the anterior pituitary?

Capillaries to vein to capillaries to vein.

Which endocrine gland is stimulated by adrenocorticotropic hormone (ACTH, or corticotropin)?

The adrenal cortex, stimulating it to make and release its hormones.

What hypothalamic and pituitary hormones drive the negative feedback loop for thyroxine production shown in this diagram?

TRH (thyrotropin-releasing hormone, hormone 1) from the hypothalamus and TSH (thyroid-stimulating hormone, hormone 2) from the anterior pituitary.

What are the two gonadotropic hormones released by the anterior pituitary, and what are their target organs?

Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH); they act on the gonads (testes and ovaries).

What growth hormone disorders result from hyposecretion in childhood versus hypersecretion in adulthood?

Hyposecretion in childhood causes pituitary dwarfism; hypersecretion in adulthood causes acromegaly.

What two substances are required by thyroid follicular cells to synthesize $T_3$ and $T_4$?

Iodine and tyrosine.

What is the physiological difference between Triiodothyronine ($T_3$) and Thyroxine ($T_4$)?

Triiodothyronine ($T_3$) contains 3 iodine atoms and is the active form regulating metabolism; Thyroxine ($T_4$) contains 4 iodine atoms and is an inactive precursor converted to $T_3$ in organs like the liver and kidneys.

What medical condition characterized by enlarged thyroid tissue is depicted here?

Simple goiter (endemic goiter), caused by a lack of iodine in the diet.

What is Congenital Hypothyroidism, and what happens if thyroid hormone is not supplemented early?

An under-secretion of thyroid hormone at birth; if thyroid hormone supplement is not provided within the first two months, it results in severe, irreversible developmental delay and short, stocky stature.

What ocular symptom is characteristic of Grave's Disease?

Exophthalmos (protrusion of one or both eyes) due to edema in eye socket tissues and swelling of eye muscles.

How does calcitonin regulate blood calcium levels when calcium is elevated?

Calcitonin is secreted by parafollicular cells to bring about calcium deposition in bones and reduce the activity and number of osteoclasts.

What are the three cortical zones of the adrenal gland, listed from superficial to deep?

1. Zona glomerulosa
2. Zona fasciculata
3. Zona reticularis

Which hormones are secreted by the adrenal medulla during stress?

Epinephrine (adrenaline) and norepinephrine (noradrenaline).

What mineralocorticoid hormone is secreted by the zona glomerulosa, and what is its effect?

Aldosterone; it increases sodium reabsorption by the kidneys, increasing blood sodium levels.

What endocrine hypersecretion causes the clinical manifestations shown in this diagram?

Cushing's Syndrome, caused by hypersecretion of adrenal cortex hormones (excess cortisol leading to diabetes mellitus and trunk fat deposition, excess aldosterone leading to hypertension).

What pancreatic duct joins the common bile duct at the hepatopancreatic ampulla as shown in this diagram?

The pancreatic duct.

What three cell types make up the endocrine pancreatic islets (Islets of Langerhans) and what hormones do they secrete?

1. Alpha cells: secrete glucagon.
2. Beta cells: secrete insulin.
3. Delta cells: secrete somatostatin.