Ch 9 Endocrine Lecture Flashcards

Vocabulary flashcards covering key endocrine system terms, glands, hormones, mechanisms, and feedback processes from the notes.

Endocrine system

System that uses hormones circulated through the bloodstream to regulate growth, development, aging, and homeostasis; slower signals than the nervous system and often works with it.

Hypothalamus

Brain region that links the nervous and endocrine systems; produces releasing and inhibiting hormones; has portal circulation to the anterior pituitary and stores oxytocin and ADH in the posterior pituitary.

Hypothalamic-pituitary portal circulation

Direct circulatory link from hypothalamus to the anterior pituitary; allows releasing/inhibiting hormones to control pituitary secretions.

Pituitary gland

Master gland that secretes many hormones; has an anterior lobe (adenohypophysis) and a posterior lobe (neurohypophysis).

Adenohypophysis (anterior pituitary)

Anterior lobe that releases hormones such as TSH, ACTH, LH, FSH, GH, prolactin, and MSH.

Neurohypophysis (posterior pituitary)

Posterior lobe that stores and releases oxytocin and ADH, produced by the hypothalamus.

Thyrotropin-releasing hormone (TRH)

Hypothalamic hormone that stimulates the anterior pituitary to secrete thyroid-stimulating hormone (TSH).

Thyroid-stimulating hormone (TSH)

Anterior pituitary hormone that stimulates the thyroid to produce T3 and T4.

Adrenocorticotropic hormone (ACTH)

Anterior pituitary hormone that stimulates the adrenal cortex to produce glucocorticoids.

Luteinizing hormone (LH)

Anterior pituitary hormone that stimulates gonads; in females triggers ovulation and estrogen/progesterone production; in males stimulates testosterone.

Follicle-stimulating hormone (FSH)

Anterior pituitary hormone that promotes maturation of eggs and sperm; gonadotropic.

Growth hormone (GH, somatotropin)

Anterior pituitary hormone that regulates growth and metabolism; influences protein synthesis and tissue growth.

Prolactin

Anterior pituitary hormone that initiates milk production after birth.

Melanocyte-stimulating hormone (MSH)

Anterior pituitary hormone associated with skin pigmentation.

Oxytocin

Posterior pituitary hormone that stimulates uterine contractions and milk ejection; also involved in bonding.

Antidiuretic hormone (ADH, vasopressin)

Posterior pituitary hormone that increases water reabsorption in kidneys, concentrating urine.

Pineal gland

Gland in the brain that stores and secretes melatonin, influencing sleep-wake cycles.

Melatonin

Hormone from the pineal gland that regulates the circadian rhythm and sleep–wake cycle.

Thyroid gland

Endocrine gland in the neck; produces thyroid hormones (T3 and T4) and calcitonin.

Thyroid hormones (T3 and T4)

T3 (triiodothyronine) and T4 (thyroxine); regulate cellular metabolism; T3 is the active form; T4 is the storage form converted to T3; iodine is essential.

Calcitonin

Thyroid hormone that lowers blood calcium by inhibiting bone resorption and promoting calcium storage in bone.

Parathyroid glands

Four small glands on the posterior thyroid; secrete parathyroid hormone to increase blood calcium when needed.

Parathyroid hormone (PTH)

Raises blood calcium by increasing bone resorption, increasing renal calcium reabsorption, and promoting calcitriol formation.

Calcitriol

Active form of vitamin D; increases calcium absorption from the gut and works with PTH to raise blood calcium.

Islets of Langerhans

Endocrine cell clusters in the pancreas that secrete insulin and glucagon to regulate blood glucose.

Pancreas (endocrine vs exocrine)

Gland with exocrine function (ducted digestive juices) and endocrine function (islets of Langerhans) releasing hormones into the blood.

Basal metabolic rate (BMR)

Rate of oxygen consumption at rest; influenced by thyroid hormones (e.g., T3).

Calcitonin vs PTH

Calcitonin lowers blood calcium (bone storage) while PTH raises blood calcium (bone resorption, kidney activation, and intestinal absorption via calcitriol).

Sella turcica

Bony saddle in the skull where the pituitary sits; nickname for the Turkish saddle surrounding the pituitary.

Pituitary stalk

The connecting stalk between the hypothalamus and the pituitary; contains vessels and nerves linking the two.

Isthmus (thyroid isthmus)

The narrow part of the thyroid that connects the two lobes; lies over the voice box.

Parathyroid hormone action sites

PTH increases osteoclast activity, increases renal calcium reabsorption, and promotes calcitriol formation to raise blood calcium.

Osteoclast

Bone-resorbing cells activated by PTH to release calcium into the blood.

Osteoblast

Bone-forming cells (mentioned in contrast to osteoclasts in calcium regulation).

Water-soluble hormones

Hormones that dissolve in water; cannot cross the plasma membrane; use surface receptors and second messenger systems (e.g., cAMP).

Lipid-soluble hormones

Hormones that require carrier proteins in the blood; cross the plasma membrane and bind intracellular receptors to affect gene transcription.

Carrier proteins

Blood carriers for lipid-soluble hormones; help transport fats and steroid hormones through the bloodstream.

Second messenger system

Pathway where a water-soluble hormone binds a membrane receptor (first messenger) and triggers intracellular messengers (e.g., cAMP) to produce a response.

G protein

Intracellular protein activated by a membrane receptor; contributing to the production of cAMP and downstream effects.

Receptors

Proteins on target cells that bind to specific hormones; receptor density can range from 2,000 to 100,000 per cell and can be up- or down-regulated.

Synergistic effect

Two or more hormones work together to enhance a target cell response.

Antagonistic effect

Hormones with opposite effects (e.g., insulin lowers blood glucose, glucagon raises it).

Permissive effect

One hormone increases a target cell’s sensitivity to another hormone.

Negative feedback loop

A loop in which rising levels of a hormone inhibit further release; maintains homeostasis (e.g., blood glucose regulation).

Positive feedback loop

A loop in which a hormone release stimulates more release until a final event occurs (e.g., oxytocin during childbirth).

Hormones

Specialized chemical messengers that act on target cells to initiate and regulate multiple physiologic responses

Circulating hormones

Majority that are secreted into the bloodstream and circulated throughout the body

Target cells

When a hormone is circulated through the body, only it's______ ______ have the appropriate receptors to bond with the hormone to produce a physiologic response.

Small

Some hormones have a_____ number of target cells and produce more specific types of responses.

Cellular responses

Can include protein synthesis, increased cellular transport, changes in plasma membrane permeability, and changes in metabolic reactions and rates

Water soluble and lipid soluble

Two broad categories of hormones

Water soluble hormones

Most hormones

made up of amino acids

Peptides

Very simple molecules, while others are made of chains of between 3 and 49 amino acids

Proteins

Longer water soluble hormones, chains of 50 to 200 amino acids

Lipid soluble hormones

Include steroid hormones, which are made up from cholesterol and thyroid hormones, which are composed of a specific amino acid and iodine

Easily, phospholipid

Water soluble hormones are ____ transported through the blood, they cannot pass through the plasma membrane of target cells due to the______ structure of the membrane.

Integral membrane proteins (IMPs)

Receptors on the surface of water soluble hormones the recognize them

G protein

The connection between hormone and receptor activates an intracellular protein called

ATP, cyclic adenosine mono phosphate aka cyclicAMP (cAMP)

G protein initiates the conversion of___ in the cytoplasm into ________

cAMP

The presence of ____ intern activates proteins within the cell that produce a designated physiologic change.

Second messenger mechanism

The sequence of events within the cell that produce a designated physiologic change are called

Synergistic effect

Two or more hormones may act together to enhance or intensify a target cells response

Antagonistic effect

Other hormones oppose the actions of one another having an ______ ______ on the target cells (ie insulin and glucagen)

Insulin

Decreases the amount of glucose in the bloodstream

Glucogon

Increases blood glucose

Permissive effect

Increases a target cells sensitivity to another hormone

Thyroid hormone does this for adrenaline

Negative feedback mechanism

The frequency of quick bursts of hormone to increase blood level of hormone is regulated through….

Positive feedback mechanism

The physiologic response reinforces the original stimulus to continue the release of the hormone

3 ways endocrine glands may be stimulated to release their hormones yeah better

Hormonal stimulus

Changes in blood concentrations

Neurologic stimulus

Hormonal stimulus

Many glands are stimulated by hormones from other endocrine glands or tissues

Hypothalamus, pituitary

A prime demonstration of hormonal stimulus is the relationship between the ________ and ______

Stimulating, inhibiting

Hypothalamus releases_______ and _______ hormones that control the function of the pituitary

Changes in blood concentrations

It change in the level of a specific ion or nutrient in the blood stimulates hormone secretion

Changes in blood concentrations

Calcitonin release from the thyroid gland is an example of the sort of stimulus

Neurologic stimulus

In few cases, neurons stimulate specific glands to release hormones

Neurologic stimulus

Relationship between the hypothalamus, posterior pituitary and the sympathetic stimulation of the adrenal glands are an example of this type of endocrine gland activation

Major endocrine glands

Pituitary, pineal, thyroid, parathyroids, thymus, adrenal gonads (ovaries & tested), and pancreas.

Not

Endocrine oregons are____ structurally linked

together

The systems individual glands and specialized tissues function_____ to secrete hormones directly into blood and lymph

ductless

Endocrine glands

Exocrine glands

Have ducts that deliver their secretions to specific locations ie sebaceous glands in the skin and salivary glands

pancreas and gonads

Have dual functions as both endocrine and exocrine glands

Only Endocrine glands (not Exocrine)

Pituitary, pineal, thyroid, parathyroids, thymus, and adrenals

Hypothalamus

A structural component of the brain that functions as the control center for autonomic functions and as a key link between the nervous and endocrine system

Dual lobed pituitary gland

The inferior aspect of the hypothalamus is structurally and functionally attached to the…..

Portal circulation

Hypothalamus has a direct circulatory link to the anterior pituitary called…..

Releasing, inhibiting

Hypothalamus produces several_____ hormones and______ hormones, which it releases into portal circulation

Anterior

The hypothalamus controls and regulates all_______ pituitary secretions

Posterior

The hypothalamus has a neuronal link with the_____ lobe of the pituitary

Neurosecretory cells

Where oxytocin and antidiuretic hormone are transported to the posterior pituitary lobe along special neurons known as

Posterior

Neurosecretory cells are stored in the _____ pituitary until the hypothalamus signals their release by a nerve impulses

Pituitary gland

size of a pee, considered the keystone, or master gland of the endocrine system because the hormones it releases stimulate other endocrine glands

Hypothalamus

Pituitary is directed by the…..

Pituitary stall

Pituitary gland is suspended from the inferior aspect of the hypothalamus by the

Pituitary gland

Rests in the small depression of the sphenoid bone aka sella turica

Neurohypophysis

Pituitary gland-what mostly nerve tissue, posterior lobe

Groth, homeostatic

The anterior pituitary produces and secretes a variety of hormones that influence_____ and ______ process.

Tropic hormones

Hormones that stimulate other endocrine glands

Adenohypophysis

Pituitary gland -Composed of glandular tissue anterior lobe

4 tropic hormones

Thyroid stimulating hormone (TSH)

Adrenocorticotropic hormone (ACTH)

Luteinizing hormone (LH)

Follicle stimulating hormone (FSH)