A&P Chapter 10: Endocrine System

What do endocrine glands do?

What do endocrine glands do?

Release hormones into the bloodstream, which circulate through the bloodstream until they reach their target cells.

Each specific hormone binds to what?

A specific receptor that fits it, they fit like a “lock and key”

Each hormone only affects?

Target cells with receptors for that hormone

Steroid hormones are?

Lipid-soluble

Can or cannot steroid hormones pass through the cell membrane of target cells?

They can pass through the cell membrane of target cells

Steroid hormones bind to receptors that are located where?

In the cytoplasm or nucleus of target cells

Non-steroid hormones are?

Not lipid soluble

Can or cannot non steroid hormones pass through the cell membrane of target cells?

They cannot pass through the cell membrane of target cells

Non steroid hormones bind to receptors found where?

In the cell membrane of target cells

Hormonal Stimulus:

A hormone from one endocrine gland can stimulate another endocrine gland to secrete its hormones

Example of hormonal stimulus:

The hypothalamus releases the hormone gonadotropin-releasing hormone (GnRH) which stimulates the pituitary gland to release hormones called gonadotropins that regulate sex organs.

Humoral Stimulus:

(Humor means fluid in blood) Changes in the nutrient levels in the bloods can stimulate the release of certain hormones.

Low levels of glucose in the bloodstream stimulates what organ to release what hormone ?

(humoral stimulus) Stimulates the pancreas to release glucagon

High levels of glucose in the bloodstream stimulates what organ to release what hormone?

(humoral stimulus) Stimulates the pancreas to release insulin

Hormones help maintain?

Homeostasis of nutrient levels

Neural stimulus:

The brain and spinal cord send signals to stimulate the release of certain hormones

The nervous system stimulates what to release what hormone?

(neural stimulus) Stimulates the adrenal glands to release epinephrine

Growth and development processes stimulate:

mitosis (cell division), synthesis of certain proteins, and gene activation: transcription/translation

Growth and development hormones target what receptors?

Receptors in the nucleus

Metabolism hormones have what functions?

Stimulate production and use of ATP, and activation of specific enzymes needed for cell metabolism

Metabolism hormones target what receptors?

Receptors in the mitochondria

Nutrient balance, and water and electrolyte balance hormones have what functions?

Changes membrane permeability of target cells

How do nutrient balance, and water and electrolyte balance hormones affect target cells?

They insert or delete ion channels or glucose transporters in the cell membrane of target cells

Reproductive system hormones have what function?

Stimulate production of sperm cells or egg cells

T or F: If the concentration of a hormone is high enough, every body cells will respond to it.

False, hormones only affect target cells.

What hormone does the pineal gland produce?

Melatonin

What is the stimulus for melatonin release?

Darkness

Melatonin regulates what?

The circadian rhythm

Circadian rhythm:

24-internal clock (reason why you sleep and wake up around the same time each day)

How does light dimness go through to the pineal gland?

Light stimulates retina, retina sends signal to hypothalamus, hypothalamus indirectly sends signals to pineal gland. (decrease in light = more signals are sent to pineal gland)

Antioxidant activity:

Melatonin helps prevent the brain from free radicals.

Various releasing hormones from the hypothalamus stimulate the release of specific hormones from the:

Anterior pituitary gland

Releasing hormones travel through what to get from the hypothalamus to the anterior pituitary gland?

Hypophyseal portal system

How does the hypophyseal portal system help communication between the two organs?

It allows for a fast communication

What are the two hormones that are produced in the hypothalamus and stored in the pituitary gland?

Oxytocin and Antidiuretic Hormone (ADH)

The hypothalamus sends electrical signals to where to release what hormone?

the adrenal glands, epinephrine (E)

Releasing hormones from the hypothalamus are an example of what type of stimulus?

Hormonal stimulus

Electrical signals from the hypothalamus are an example of what?

Neural stimulus

The anterior pituitary gland produces and secretes what type of hormones that stimulate other endocrine glands to do what?

tropic hormones, secrete hormones

Tropic hormones are regulated by what?

Negative feedback

Thyroid Stimulating Hormone (TSH):

From the anterior pituitary gland, stimulates the thyroid gland to produce and release thyroid hormone (T3 and T4)

How is TSH regulated by negative feedback?

Increased (high) levels of thyroid hormones in the bloodstream inhibit TSH release.

Adrenocorticotropic Hormone (ACTH):

From the anterior pituitary gland, stimulates the adrenal glands to produce and release the hormone cortisol

How is ACTH regulated by negative feedback?

Increased (high) levels of cortisol in the bloodstream inhibit ACTH release.

Growth Hormone (GH):

Produced and secreted by the anterior pituitary gland, stimulates growth, protein synthesis, and cell division.

How does GH stimulate protein synthesis?

By stimulating cells to absorb amino acids and by stimulating gene transcription

Where does GH mainly stimulate cell division at?

Bone cartilage and skeletal muscle.

What are GH metabolic effects?

Stimulates the breakdown of stored fats, the fatty acids are used for energy instead of glucose, GH helps increase blood glucose levels.

GH stimulates the breakdown of what?

Fats and glycogen.

Where is glycogen stored?

In the liver and skeletal muscle

When glycogen is broken down what happens?

Glucose is released into the blood, which increases blood glucose levels

Stimulus for ADH release:

Increased blood osmolarity (dehydration), low (decreased) blood volume, low (decreased) blood pressure.

How does ADH work with the renal system?

ADH targets the kidneys and stimulates water reabsorption from the kidneys into the bloodstream.

Does blood pressure and blood volume increase or decrease when water reabsorbs from the kidneys to the bloodstream due to ADH?

Increase (higher)

Does the amount of water lost in urine increase or decrease when water reabsorbs from the kidneys to the bloodstream due to ADH?

Decreases (less)

What would elevated blood levels of cortisol, a hormone from the adrenal gland, have on secretion of ACTH from the pituitary gland?

Decreased (less) ACTH secretion

Thyroid Hormones are made up of what amino acid?

Tyrosine with iodine atoms attatched

What are the two thyroid hormones?

T3 and T4

T3 and T4 increase what in almost all cells of the body?

Metabolism

T3 and T4 stimulate what?

They stimulate the production and use of ATP

What is needed for ATP production, and what is a byproduct of ATP production?

O2, heat

T3 and T4 affect which organelle inside target cells?

Mitochondria

T3 and T4 are necessary for proper what?

Growth and development

T3 and T4 work with what hormone, and what are they specifically needed for?

Growth hormone, bone growth and brain development

How many parathyroid glands are on what side of the thyroid gland?

4, posterior

Stimulus for Parathyroid Hormone (PTH) release:

Low blood Ca+ levels

What does PTH help do overall?

Increase blood Ca2+ levels

How does PTH help increase blood Ca+ levels?

Breaks down bone matrix which causes Ca2+ to be released into the blood.

PTH stimulates Ca2+ reabsorption in kidneys.

PTH helps increase Ca2+ absorption into the blood in the intestines.

If someone is not getting enough iodine in their diet, will their blood levels of TSH likely be high or low?

High, because it will continue to release because the anterior pituitary gland will not get a signal that T2 and T4 are regulated.

Beta cells of the pancreas produce and secrete what hormone?

Insulin

Stimulus for insulin release is?

High blood glucose levels

Insulin helps do what?

lower (decrease) blood glucose

Insulin stimulates skeletal muscle to do what?

To take in glucose and use glucose for energy (ATP production)

After insulin stimulation any glucose not used immediately is stored as what in where?

Stored as glycogen in skeletal muscle cells

Insulin also stimulates cells to take in what, which is used to make what?

amino acids, protein

What organs don’t rely on insulin to take in glucose?

The brain and heart

Insulin also stimulate what organs cells to store unused glucose as _____?

Liver cells, glycogen, where a limited amount can be stored

Insulins message to the body:

“Use glucose for energy and store everything else”

Insulin stimulates adipose tissue to take in what, and store it for ___?

excess glucose, fat

Alpha cells of the pancreas produce and secrete:

Glucagon

Stimulus for glucagon release is:

Low blood glucose levels

Glucagon helps do what to blood glucose levels?

Raises (increases) blood glucose levels

Glucagon stimulates the liver cells to do 2 things, what are they?

Breakdown glycogen to glucose, produce glucose from amino and fatty acids.

When insulin is not secreted, other cells in the body use what for energy instead of glucose?

Fats

Ketones are formed during what?

Fat metabolism

What organ uses ketones for energy when glucose is not available?

The brain

Do ketones decrease or increase blood pH?

Decrease (blood becomes more acidic)

Glucagon’s message to the body:

“Save glucose for the brain, but its not an emergency”

Secretion from the pancreas is regulated by what feedback loop?

Negative feedback loop

As blood glucose levels decline will more or less insulin be secreted from the pancreas?

Less

The outer cortex region of the adrenal glands produce and secrete what 2 hormones?

Aldosterone and cortisol

Stimuli’s for aldosterone release:

Low blood Na+ levels

High blood K+ levels

Low blood volume or low blood pressure

Aldosterone targets what organ? What 2 things does that stimulate?

Kidneys, Na+ reabsorption from the kidneys into the bloodstream and K+ secretion out of the bloodstream and into kidney tubules.

_____ follows Na+ into the bloodstream by _____ which helps _____ blood volume and pressure.

Water, osmosis, increase

Aldosterone works with what other hormone to increase water reabsorption and therefore helps increase blood pressure?

Antidiuretic Hormone (ADH)

How do ADH and Aldosterone affect urine volume?

Decreases urine volume

When K+ secretes out of blood into kidney tubules K+ blood levels do what?

Decrease (More K+ is excreted in urine

Adrenocorticotropic Hormone (ACTH) from the anterior pituitary gland stimulates the adrenal cortex to produce and release:

Cortisol during periods of stress

Cortisol stimulates what 3 different breakdowns?

Tissue breakdown to help prevent hypoglycemia (low blood sugar) and to ensure the body has fuel during stress

Fat breakdown in adipose tissue and release of fatty acids into the blood

Protein breakdown in muscle/connective tissue and release of amino acids into the blood

Cortisol stimulates the liver to do what?

To produce glucose from amino and fatty acids