Unit III Endocrine System Exam Review

Synergism

More than one hormone produces the same effects on target cell.

Lipid-derived hormones

Must travel to their target cell bound to a transport protein due to blood being water-based.

Half-life of steroid hormones

Much longer than that of hormones derived from amino acids.

Binding of lipid soluble hormones

Lipid soluble hormone diffuses through plasma membrane, binds with receptor in cytoplasm, forming a receptor-hormone complex that enters the nucleus and triggers gene transcription.

Steroid hormone action

A steroid hormone directly initiates the production of proteins within a target cell.

Binding of water-soluble hormones

Water soluble hormones are membrane insoluble and bind to membrane receptors.

G protein activation

Binding of water-soluble hormones activates a G protein.

Adenylyl cyclase

Activated by G protein, it catalyzes the conversion of ATP to cAMP, the secondary messenger.

cAMP function

Activates protein-kinases.

Protein kinases

Phosphorylate proteins in the cytoplasm, activating them to alter cell activity.

Erythropoietin (EPO)

A hormone produced by the kidneys in response to low oxygen levels, stimulating the production of red blood cells.

Osmoreceptors

Specialized cells within the hypothalamus that monitor blood osmolarity.

ADH release

Triggered by osmoreceptors in response to high blood osmolarity.

Melatonin production

Varies according to the level of light received from the environment.

Pineal gland

Contains pinealocyte cells that produce and secrete the hormone melatonin.

Melatonin origin

Derived from serotonin.

Water-soluble hormones action

Must bind to a surface cell-membrane receptor to initiate a cell-signaling pathway.

Cell-signaling pathway components

Involves G proteins, adenylyl cyclase, cyclic AMP (cAMP), and protein kinases.

Effect of high blood osmolarity

Can occur during dehydration or following a very salty meal.

Response to low oxygen levels

EPO stimulates the production of red blood cells in the bone marrow.

Osmoreceptors response to blood osmolarity decrease

Prompt a corresponding decrease in the secretion of ADH.

Function of protein phosphorylation

Activates proteins in the cell that carry out changes specified by the hormone.

Melatonin

A hormone whose production is inhibited by increased light levels, promoting wakefulness, and increases in response to declining light levels, causing drowsiness.

Glucagon

A hormone produced by alpha cells in the pancreas that increases blood sugar levels and targets the liver.

Estrogen

A hormone responsible for thickening the endometrial lining during the proliferative phase of the menstrual cycle.

Progesterone

A hormone produced by the corpus luteum that maintains the thickness of the endometrial lining during the secretory phase.

Corpus Luteum

A structure that secretes progesterone and degrades in the absence of fertilization, ceasing progesterone production.

Luteinizing Hormone (LH)

A hormone that triggers ovulation and stimulates the production of estrogens and progesterone by the ovaries.

Pancreas

An organ that has both endocrine and exocrine functions, located in the crook of the duodenum.

Exocrine Cells

Cells in the pancreas (acini cells) that secrete alkaline digestive enzymes into ducts.

Endocrine Cells

Cells in the pancreas (pancreatic islets) that secrete hormones like glucagon, insulin, somatostatin, and pancreatic polypeptide.

Alpha Cells

Cells in the pancreatic islets that produce glucagon and make up approximately 20 percent of each islet.

Beta Cells

Cells in the pancreatic islets that produce insulin and make up approximately 75 percent of each islet.

Delta Cells

Cells in the pancreatic islets that secrete somatostatin, accounting for four percent of the islet cells.

PP Cells

Cells in the pancreatic islets that secrete pancreatic polypeptide and account for about one percent of islet cells.

Somatostatin

A peptide hormone secreted by delta cells that inhibits the release of both glucagon and insulin.

Pancreatic Polypeptide

A hormone thought to play a role in appetite regulation and pancreatic secretions, released following a meal and during fasting.

Aldosterone

A hormone important in regulating sodium and potassium ions in urine, released in response to elevated blood K+, low blood Na+, low blood pressure, or low blood volume.

Negative Feedback Loop

A regulatory mechanism in which the activity of glucagon is controlled to maintain blood glucose levels.

Proliferative Phase

The phase of the menstrual cycle during which estrogen thickens the endometrial lining.

Secretory Phase

The phase of the menstrual cycle during which progesterone maintains the thickened endometrial lining.

Insulin

A hormone produced by beta cells that decreases blood sugar levels and stimulates glucose transport into cells.

Blood Glucose Regulation

The process by which hormones like glucagon and insulin maintain stable blood sugar levels.

Elevated Blood K+

A condition that triggers the release of aldosterone to increase potassium excretion and sodium retention.

Low Blood Na+

A condition that stimulates aldosterone release to retain sodium and increase blood volume.

CRH

Corticotropin-releasing hormone from the hypothalamus that triggers ACTH release from the anterior pituitary.

ACTH

Adrenocorticotropic hormone released from the anterior pituitary that signals the adrenal cortex to secrete aldosterone.

Cortisol

Hormone produced by the adrenal cortex, specifically from the zona fasciculata, important for glucose metabolism.

Zona Fasciculata

Layer of the adrenal cortex that produces glucocorticoids, including cortisol.

Glucocorticoids

Hormones produced by the adrenal cortex that play a role in glucose metabolism.

Cortisone

A substance that cortisol is converted to by the liver.

Skeletal Muscle Cells

Primary target cells for insulin that facilitate glucose uptake.

Adipose Cells

Another primary target for insulin that facilitates glucose uptake.

Glucose-dependent Insulinotropic Peptide

Gastrointestinal hormone that triggers insulin production and secretion by pancreatic beta cells.

Tyrosine Kinase Receptor

Receptor activated by insulin that triggers phosphorylation of substrates within the cell.

Neurohypophysis

Posterior pituitary that is neural tissue and does not produce hormones but stores them.

Adenohypophysis

Anterior pituitary that is glandular tissue and produces hormones.

Hypophyseal Portal System

Network of capillaries connecting the hypothalamus to the anterior pituitary, allowing hormone transport without systemic circulation.

Superior Hypophyseal Artery

Artery that branches off the carotid arteries and transports blood to the hypothalamus.

Pars Distalis

Largest part of the adenohypophysis.

Pars Intermedia

Slender part of the adenohypophysis.

Pars Tuberalis

Part of the adenohypophysis that wraps around the infundibulum.

Releasing Hormones

Hormones secreted by the hypothalamus that stimulate the secretion of hormones from the anterior pituitary.

Inhibiting Hormones

Hormones secreted by the hypothalamus that inhibit the secretion of hormones from the anterior pituitary.

Infundibulum

Structure that connects the hypothalamus to the anterior pituitary and contains the hypophyseal portal system.

Anterior Pituitary

Gland that originates from the digestive tract in the embryo and manufactures hormones regulated by hypothalamic hormones.

Adenohypophysis hormones

Includes TSH, ACTH, FSH, LH, ICSH, prolactin, GH, and MSH.

ADH

Antidiuretic hormone stored in the posterior pituitary.

Oxytocin (OT)

Hormone released by neurosecretory cells in the hypothalamus into the posterior pituitary.

Posterior pituitary

An extension of the neurons of the paraventricular and supraoptic nuclei of the hypothalamus.

Paraventricular nuclei

Produce the hormone oxytocin.

Supraoptic nuclei

Produce ADH.

Progesterone decline

Triggers the shedding of the stratum functionalis of the endometrium.

Granulosa cells

Surround the oocyte and transition from a flat shape to a rounded, cuboidal shape as they proliferate.

Theca cells

Work with granulosa cells to produce estrogens.

Estradiol

A type of estrogen produced by granulosa and theca cells in response to LH stimulation.

Zygote

The single-cell organism formed immediately after the fusion of a sperm cell and an egg cell during fertilization.

Ductus venosus

A fetal circulatory shortcut that connects the umbilical vein to the inferior vena cava.

Ductus arteriosus

A fetal circulatory shortcut that connects the pulmonary artery to the aorta.

Foramen ovale

A fetal circulatory shortcut that allows blood to bypass the right ventricle.

Umbilical arteries

Carry deoxygenated blood from the fetus to the placenta.

Umbilical veins

Carry oxygenated blood from the placenta to the fetus.

Fetal circulatory system

Integrated with the placenta via the umbilical cord to receive oxygen and nutrients.

Menstrual cycle end

Triggered by a drop in progesterone leading to the shedding of the endometrial lining.

Follicle development

Granulosa and theca cells increase in number and size, producing more estrogen in response to LH.

Capillary plexus

A network of capillaries involved in the transport of hormones to and from the anterior pituitary.

Shunt

An anatomical (or sometimes surgical) diversion that allows blood flow to bypass immature organs such as the lungs and liver until childbirth.

Umbilical vein

The vein that provides the fetus with necessary oxygen and nutrients from the placenta.

Ductus venosus shunt

A shunt that allows oxygenated blood from the umbilical vein to flow toward the inferior vena cava, bypassing the immature liver.

Colostrum

A thick, yellowish substance high in protein but containing less fat and glucose than mature breast milk, produced in the final weeks of pregnancy.

Gastrulation

The process during the third week of development where the two-layered disc of cells becomes a three-layered disc.

Totipotent cells

Cells that have the potential to differentiate into any cell type in the human body, lasting for only a few days.

Multipotent cells

Cells that can develop into multiple, but limited types of cells within a specific tissue or organ system, such as hematopoietic stem cells.

Descending aorta

Carries partially oxygenated and partially deoxygenated blood into the lower regions of the body.

Placenta

An organ that filters wastes from fetal blood and allows oxygen and nutrients from the mother to diffuse into the fetal blood.

Myocardium

The muscular tissue of the heart that receives oxygenated blood from the coronary arteries.

Carotid arteries

Arteries that carry oxygenated blood to the brain.

Pulmonary trunk

The vessel that splits into pulmonary arteries, carrying blood from the right ventricle to the lungs.

Inferior vena cava

The vein that carries deoxygenated blood from the lower body to the right atrium of the heart.

Right atrium

The chamber of the heart that receives deoxygenated blood from the inferior vena cava and mixes it with fetal venous blood.