Anatomy & Physiology ~ Endocrine System

What does endocrine mean?

To secrete within

What does the endocrine system influence?

Metabolic activities of cells by means of hormones

What is the function of the endocrine system?

integrates body systems (homeostasis) by using chemical messengers (hormones) communication.

What are the effectors of the endocrine system?

responsive body parts - autonomic nervous system

What are the major endocrine glands?

Hypothalamus, pituitary gland, pineal gland, thyroid gland, parathyroid gland, thymus, adrenal gland, pancreas, sex organs.

One cell is capable of more than one activity.

True

How does a hormone find its target tissue?

The cell must have a protein identifier and receptor.

What are the glandular functions?

endocrine and exocrine

What are endocrine glands?

ductless glands that release hormones that control metabolic processes.

What are exocrine glands?

Glands with ducts that release to the outside of the body, such as sweat and sebaceous glands.

What is a hormone?

substance secreted by an endocrine gland into the blood stream that acts on a specific target tissue to produce a given response.

What is the function of hormones?

To alter metabolic activity. They are target specifc and have a predictable response.

What can influence hormone levels?

Stress, infection, changes in balance of fluid and minerals in blood. (example: calcium levels)

Are large or small amounts of hormones needed to get desired response?

Small amounts. Hormones are very potent and have long-lasting effects in target cells.

Are hormones regulated by positive or negative feedback?

Negative feed back

What are tropic hormones?

Hormones that target other endocrine glands to stimulate their growth/secretions. Cause a series of reactions to achieve ultimate goal, domino affect.

Which hormones target reproductive tissues/glands?

Sex hormones

Anabolic hormones stimulate what?

Anabolism (building up) in target cells.

What are local hormones?

hormones that are not transported through the bloodstream

What do paracrine secretions do?

act on neighboring cells

What do autocrine secretions do?

act on the source cell itself

What are prostaglandins?

group of compounds, paracrine substances, that mimic hormones. Produced by tissues for a particular organ. Regulate cellular response to hormones, wide variety of functions. Act locally. Very potent,

What are 2 hormone classifications?

Steroid and nonsteroid

What are steroids produced from?

Cholesterol

What is a steroid made of?

Structural lipids.

How does a steroid enter a cell?

Enter the cell by diffusion because both the hormone and cell wall are fats, lipids.

Where is the receptor for a steroid located?

in the nucleus.

Steroid hormones are insoluble in what?

water

What does the hormone do to the cell?

Alters the chemical process of the cell

nonsteroids are produced from what?

Amino acids, protein based

How does a nonsteroid enter a cell?

Facilitated diffusion. Requires a receptor on the target cell membrane.

What is the process by which a nonsteroid enters a cell?

Hormone binds to receptor on cell membrane. Hormone passes message on to 2nd receptor inside the cell which carries out the cellular changes.

What changes take place in a cell when a hormone causes the opening or closing of ion channels?

Alters plasma membrane permeability and/or changes membrane potential.

Hormone action can stimulate what kind of synthesis inside the cell?

Protein synthesis (speed up)

What are some cell changes that take place as result of hormone action?

Activate/deactivate enzyme systems. Induce secretory activity. Stimulate mitosis.

Hormones activate which cells?

Target cells which are identified by specific receptors for the hormone to bind to.

What are the 3 factors that target cell activation depends on?

Blood levels of the hormones. Number of receptors on the target cells. MOre receptors = greater response. The affinity of those receptors for the hormone.

*number of receptors on target cells may change.

What is up-regulation?

increase in number of receptors on target cell due to prolonged decrease in the level of a hormone.

What is down-regulation?

Decrease in number of receptors on a target cell due to prolonged increase in the level of hormone.

What is the hypothalamus?

Collection of specialized cells located in the lower central part of the brain.

Not a gland, part of the brain.

What does the hypothalamus connect?

The endocrine and nervous system.

What does the hypothalamus control?

The pituitary gland by producing chemicals that either stimulate or supress hormone secretions from the pituitary.

How does the hypothalamus control the pituitary gland?

Hypothalamic releasing hormones stimulate cells of anterior pituitary to release hormones.

Nerve impulses from the hypothalamus stimulate nerve endings in the posterior pituitary gland to release hormones.

What is another name for the pituitary gland?

Hypophysis

What is the pituitary gland?

A two-lobed organ (front and back) that secretes major hormones.

Where is the pituitary gland located?

At the base of the brain in the sella turcica. (saddle in the sphenoid). Attached to the hypothalamus by infundibulum.

The pituitary is divided into how many sections?

2 sections. The anterior and the posterior.

What is the anterior pituitary?

Adenohyphophysis. Upward projection of pharynx. Made of glandular tissue. Produces and releases hormones.

What is the posterior pituitary?

Neurohypophysis. Downward projection of brain. Made of neural tissue. Stores hormones.

What hormones do the anterior pituitary secrete?

Growth Hormone (GH), Thyroid Stimulating Hormone (TSH), Adrenocorticotropic hormone (ACTH), Follicle Stimulating Hormone (FSH), Luteneinizing Hormone (LH), Prolactin (PRL)

What hormones do the posterior pituitary secrete?

Oxytocin (OT), Antidiuretic Hormone (ADH)

The hypothalamus stimulates the anterior pituitary by?

Sending out hormones

What do releasing hormones do?

Stimulate the synthesis and release of hormones

What do inhibiting hormones do?

shut off the synthesis/release of hormones

What is another name for the growth hormone?

Somattropin (STH)

What is the GH?

Anabolic, tissue building, hormone

What does the growth hormone do?

Stimulates increase in size and rate of body cells (mitosis). Controls growth of the body. Promotes growth of long bones , muscles, and other tissues.

What stimulates secretion of the growth hormone?

Growth hormone releasing hormone (GHRH)

What inhibits the secretion of growth hormone?

Somatostatin (SS)

What is caused by decreased levels of GH?

dwarfism

What is gigantism?

Increased levels of GH during the growth years.

What acromegaly?

Increased levels of GH after growth years.

What is prolactin (PRL)

hormone found in males and females. Promotes milk production in females. Decreases testosterone levels in males if too high.

Prolactin is inhibited by what hormone?

Prolactin release inhibiting hormone (PRIH)

What is Thyroid Stimulating Hormone (TSH)?

Controls secretions of hormones from the thyroid gland. COntroled by thyrotropin releasing hormone

What is another name for Thyroid Stimulating Hormone?

Thyrotropin

What is another name for adrenocorticotropic hormone (ACTH)?

Corticotropin

What does ACTH control

Some secretions of adrenal cortex of te adrenal glands

What is ACTH controlled by?

Corticotropin -releasing hormone

What is Follicle -Stimulating Hormone also known as?

gonadotropic hormone

What does the FSH stimulate?

Development (maturation) of egg containing follicles in ovaries. Follicular cells to secrete estrogen. production/maturation of sperm cells.

When is FSH not present?

In prepubertal girls/boys

What is FSH controlled by?

Gonadotropin-releasing hormone (GnRH)

What is luteinizing hormone (LH) also known as?

gonadotropins

What does LH promote?

secretions of sex hormones

What does LH stimulate?

release of egg (ovulation) from ovary. stimulates seretion of testosterone.

What is LH controlled by?

gonadotropin releasing hormone (GnRH)

Does the Posterior Pituitary release hormones?

No

What does the Posterior Pituitary contain?

Nerve fibers and neuroglial cells called pituicytes.

What is stored in the posterior pituitary?

hormones that are produced by the hypothalamus. (ADH/OT)

Secretory cells of the hypothalamus are called?

neurosecretory cells

What is the antidiuretic hormone? (ADH)

Helps to help avoid dehydration or water overload

What does the ADH target?

Distal convoluted tubules

What does ADH prevent?

urine formation

What does ADH cause to happen?

Causes kidneys to reduce water excretion keeping water in the bloodstream. In high concentrations it raises blood pressure.

What does Oxytocin (OT) stimulate?

Stimulates uterine contractions (smooth muscle), and milk ejection reflex.

Oxytocin is produced by?

Hypothalmus in response to uterine and vaginal wall stretching and stimulation of breasts.

What is the thyroid gland?

Largest endocrine gland. Located on the anterior neck, wrapping the anterior portion of the trachea, below the larynx. Vascular with two large lateral lobes, connected by the isthmus.

thryoxine (T4) and Triiodothyronine (T3) are

2 iodine containing compounds released by the thyroid.

What do T4 and T3 do?

regulate rate of metabolism of carbohydrates, lipids, and proteins. INcrease metabolic rate, regulates tissue growth. T4 is in greater amounts. T3 is more potent. Released from carbohydrates.

What controls T4 and T3

Thyroid stimulating hormone (TSH)

What does calcitonin lower?

Blood calcium and phosphate ion concentrations by inhibiting release of calcium and phosphate from bones.

What does calcitonin increase?

The rat at which calcium and phosphate are deposited in the bones. (osteoblasts)

What is the order of operations for the thyroid?

Hypothalamus, thyrotropin releasing hormone (TRH), anterior pituitary, Thyroid stimulating hormone (TSH), Thyroid

What is the parathyroid gland?

four, small, yellowish, bean-shaped, encapsulated glands located on the posterior surface of the thyroid.

What does the parathyroid hormone (PTH) increase?

blood calcium levels by stimulating osteoclast production and inhibiting osteoblast production.

WHat does PTH decrease?

blood phosphate levels.

What does PTH stmulate?

kidneys to retain calcium and excrete phosphate. Promotes calcium absorption by intestines. Calcium is used in muscle contractions.

What are the Adrenal glands?

Pyramid-shaped glands located on top of each kidney.

What are the adrenal glands divided up into?

Two sections. The adrenal cortex, the outer region; and the adrenal medulla, the inner region.