Chapter 10 test

What is the endocrine system

• the endocrine system helps maintain homeostasis by releasing chemical hormones from various tissues of glands into the bloodstream, where they produce a specific effect on target cells

What is the endocrine gland

• ductless gland that secretes hormones into the bloodstream

What are hormones

• chemical messenger released by a tissue or gland in one part of the body that affects target cells in another part of the body

What are exocrine glands

• glands that release secretions into ducts that lead outside the body or into cavities

• in other words They pump fluids through tubes onto body surfaces or into body spaces.

• ex: sweat glands, salivary glands, glands of the pancreas

What are the differences between the endocrine vs nervous system

• endocrine:

  • primarily chemical in nature

  • slower and longer acting effects

  • affects a broader range of cell types

• Nervous:

  • electrochemical in nature

  • rapid and short-lived effects (ex: heart rate)

  • specific cell types affected per pathway

What are some similarities between the endocrine and nervous system

• aid in cellular communication and control

• help regulate homeostasis for multiple variables

• some overlaps in structure (I.e. cells in hypothalamus are nervous system structures that secrete hormones too)

• several chemicals can function as both hormones and neurotransmitters (I.e. epinephrine)

• both are regulated by feedback loops

name endocrine glands

Describe the steps in hormone action on target cells

1. Hormones released from tissue/gland into bloodstream

2. hormones exit bloodstream and attach to specific receptor proteins on or within target cells

• (like a lock and key); non-target cells will not possess receptor proteins for the hormone

3. target cells respond to the chemical message sent by the hormone

ex: human growth hormone is secreted by the anterior pituitary and interacts with muscle and bone cells for growth and cell division

What are the two types of hormones? how do they differ

1. Steroid / lipid-soluble hormones

2. Protein/ water-soluble hormones

• these different types of hormones differ in how they bind their receptor proteins and how they affect their target cells

Describe the way steroid hormones do their hormone action on target cells

1. Easily diffuse through lipid-bilayer of cell membranes

2. bind to receptor proteins inside nucleus of cell

3. hormone-receptor complex activates (or deactivates) a specific gene and the synthesis (or cessation) of a specific RNA molecule

4. RNA transported out of nucleus to ribosomes where protein synthesis occurs

common ex:testosterone, estrogen, aldosterone

name a few examples of steroid hormones

• testosterone

• estrogen

• aldosterone

Describe the way protein hormones do their hormone action on target cells

1. bind to a receptor protein on the surface of the target cell

2. leads to activation of a special enzyme that changes ATP to cAMP, which is often referred to as a second messenger

3. cAMP activates a cascade of reactions, whereby each reaction that occurs, triggers many more reactions

4. thus, the impact of the hormone is amplified

• (I.e. one molecule of epinephrine can trigger the breakdown of many glycogen molecules to glucose

ex: epinephrine, hGH, thydroxide (T4) , insulin

name a few examples of protein hormones

• epinephrine

• human growth hormone (hGH)

• thyroxine (T4)

• insulin

What are the 5 major features of hormones

1. only cells that contain surface or internal receptors for the hormones will respond to those hormones

2. once bound to their receptors, hormones produce a response by turning cellular processes on or off; this is done by altering the function or production of proteins in the cell

3. hormones are effective in very small concentrations because of their amplifying effects

4. the response to a hormone differs based on the target organ and even among species

5. hormones are cleared from the body by enzymatic breakdown when they are finished; the broken down products can be reused or excreted

Instead of directly affecting a target cell, what else do some hormones do instead?

• instead of directly affecting a target cell, some hormones stimulate endocrine glands to release other hormones

• these are called tropic hormones

  • many of the hormones released from the hypothalamus and anterior pituitary are tropic hormones

WHat are tropic hormones?

• hormones that stimulate endocrine glands to release other hormones instead of directly affecting a target cell

  • many of the hormones released from the hypothalamus and anterior pituitary are tropic hormones

WHat are the 4 typical mechanisms of tropic hormones

1. hypothalamus secrets the first tropic hormone, called a releasing hormone, into the anterior pituitary

2. the anterior pituitary releases the second tropic hormone, called a stimulating hormone, into the target gland

3. the target gland is stimulated to produce the third hormone that will finally produce and effect on a target tissue

4. the third hormone can operate via negative feedback loops, by preventing the release of either the first or second tropic hormones

• chemical messenger released by a tissue or gland in one part of the body that affects target cells in another part of the body

• certain hormones can only attach to specific receptor proteins on or within their target cells

• non-target cells will not possess receptor proteins for that hormone

• Differences:

  • Endocrine system is primarily in chemical nature while nervous system is electrochemical in nature

  • endocrine is slower and has longer acting effects while nervous system is rapid and short-lived effects

  • endocrine system affects a broader range of cell types while nervous system only affects specific cell types per pathway

• Similarities

  • aid in cellular communication and control

  • help regulate homeostasis for multiple variables

  • some overlaps in structure (i.e. cells in hypothalamus are nervous system structures that secrete hormones too)

  • several chemicals can function as both hormones and neurotransmitters (I.e. epinephrine)

  • both are regulated by feedback loops

• testosterone is a steroid hormone so the following steps would occur:

1. testosterone would easily diffuse through lipid-bilayer of cell membranes

2. binds to receptor proteins inside nucleus of cell

3. hormone-receptor complex activates or deactivates a specific gene and the synthesis oor cessation of a specific RNA molecule

4. RNA transported out of the nucleus to ribosomes where protein synthesis can occur

• Hormones act as the body’s master chemical messengers. Because they travel through the bloodstream to regulate virtually every tissue, organ, and cellular process, an imbalance can trigger widespread, seemingly unrelated symptoms across your entire body

• hormones are very effective even in very small concentrations because of their amplifying effects

• Steroid hormones can easily diffuse through the cell's plasma membrane because they are lipid-soluble (lipophilic) and non-polar.

• Protein hormones are water-soluble (hydrophilic) and therefore cannot pass through the membrane's core, requiring them to bind to receptors on the outside of the cell.

a) steroid hormones easily diffuse through lipid-bilayer if cell membranes

• while protein hormones bind to the receptor protein on the surface of the cell membrane

b) steroid hormone Enters the cell personally and binds to receptor proteins in the nucleus.

• while protein hormones remains outside of the cell membrane and binds to a receptor protein on the surface of the target cell

• leading to an activation if a special enzyme that changes ATP to cAMP (second messenger)

c) steroid hormones: The hormone-receptor complex activates or deactivates a specific gene and the synthesis or cessation of a specific RNA molecule

• while protein hormones: cAMP activates a cascade of reactions, whereby each reaction that occurs, triggers many more reactions

d) Steroid hormones: RNA gets transported out of nucleus to ribosomes where protein synthesis occurs

• protein hormones: when cAMP activates the cascade of reactions, whereby each reaction that occurs triggers many more reactions, the impact of the hormones is amplified

• (i.e. one molecule of epinephrine can trigger the breakdown of many glycogen molecules to glucose

label endocrine glands

How many hormones or hormone-like chemicals are in the human body? what are hormones functions in the human body?

• over 200 hormones or hormone-like chemicals in the human body

• functions include:

  • regulating growth and development,

  • speeding up or slowing down metabolism

  • regulating blood pressure and blood glucose

  • regulating the body’s immune response

What are the glands that function exclusively as endocrine glands

• pituitary

• pineal

• thyroid

• parathyroid

• adrenal

WHat are the tissues and organs that can secrete hormones but do not function exclusively as endocrine glands

• hypothalamus

• thymus

• pancreas

• testes/ovaries

What does the pituitary gland and the thyroid gland regulate

• your body’s growth, development and rate of metabolism are controlled by hormones released by the pituitary gland and thyroid gland

• the hypothalamus is important as well, as it controls the pituitary gland via releasing (tropic) hormones

WHat are the two lobes of the pituitary gland

• posterior pituitary

• anterior pituitary

Describe the posterior pituitary lobe of the pituitary gland

• technically part of the nervous system

• does not produce hormones, only stores and releases (ADH) and oxytocin

• the above hormones are produced by the hypothalamus and transferred to the posterior pituitary via special hormone carrying neurons called neurosecretory cells

Describe the anterior pituitary lobe of the pituitary gland

• true hormone synthesizing gland

• produces six major hormones:

  • TSH

  • ACTH

  • PRL

  • hGH

  • FSH

  • LH

• releasing (tropic) hormones from the hypothalamus can both stimulate or inhibit the release of the above hormones

• many of the hormones from the anterior pituitary are themselves, tropic hormones

Label posterior and anterior pituitary gland

Describe the human growth hormone (hGH)

• the hormone produced by the anterior pituitary that regulates growth, development and metabolism

• affects almost every tissue in the body

  • some tissues affected directly

  • majority of effects are tropic, especially on the liver, which is stimulated by hGH to produce insulin-like growth factor-1 (IGF-1) that affects many other cells in the body

What are the major physiological processes affected by hGH and its associated growth factors?

• protein synthesis

• cell division and growth

  • especially growth of muscle, bone and cartilage

• metabolic breakdown and release of fats’ stores in adipose (fat) tissue

What are some causes of hGH-related disorders?

• genetic mutation of hGH gene

• lesions in hypothalamus or anterior pituitary

• problems with receptor proteins on target cells

• benign tumors in the pituitary gland

Describe how hGH can cause a disorder in pituitary dwarfism

• insufficient hGH production during childhood results in pituitary dwarfism

• individual will be extremely small stature, but with typical body proportions

• hGH can stimulate the growth plates at the end of long bones, like arms and legs, causing elongation

Describe gigantism and how its caused

• excessive hGH production during childhood can lead to a condition called gigantism

  • extremely rare disorder

  • famous case: Robert Wadlow weighed 490 pounds and was 8’11 at 22 years old

Describe acromegaly and how its caused

• excessive hGH during adulthood (after skeletal growth is complete)

  • since skeletal growth is complete, excess hGH cannot lead to further increase in height, so bones and soft tissues widen

  • visible symptoms include:

    • widening of the face,

    • thickening of ribs,

    • enlargement of extremities

  • other clinical symptoms inlude:

    • enlarged organs (heart, liver, kidneys)

    • debilitating headaches

    • fatigue

    • breathing difficulties

    • cardiovascular disease

    • diabetes onset (hyperglycemia)

    • muscle weakness

What 2 hormones does the posterior pituitary store and release?

1. Antidiuretic hormone (ADH)

2. Oxytocin

Describe ADH hormone

• released by posterior pituitary when receptor cells in the hypothalamus detect increase in sodium concentration in the blood or when the body is dehydrated

• target: distal tubule and collecting duct in nephrons

• result: more permeable to water, so water can get reabsorbed via osmosis

  • also results in blood vessel constriction

• ADH production inhibited by caffeine and ethanol

• ADH production increased by nicotine, stress and any event leading to a severe drop in blood pressure

When is ADH hormone released from the posterior pituitary?

• when receptor cells in the hypothalamus detect increase in sodium concentration in the blood or when the body is dehydrated

WHat is the target of ADH hormones from the posterior pituitary? what does it result in?

• target is distal tubule and collecting duct in nephrons

• results:

  • more permeable to water, so water can get reabsorbed via osmosis

  • also results in blood vessel constriction

What stuff inhibit ADH production and increase ADH production?

• ADH production inhibited by caffeine and ethanol

• ADH production increased by nicotine, stress, and any event leading to a severe drop in blood pressure

Describe oxytocin hormone

• released from posterior pituitary when receptor cells in the female nipples stimulated or when uterus is contracting, which sends signals to the hypothalamus

• target : mammary glands or uterus

• result: mammary glands produce more milk and uterine contractions increase

• governed by a positive feedback mechanism

When is oxytocin released from the posterior pituitary

• when receptor cells in the female nipples stimulated

• or when uterus is contracting

• which sends signals to the hypothalamus

What is the target and results of oxytocin when released from the posterior pituitary

• Target is mammary glands or uterus

• results:

  • mammary glands produce more milk

  • and uterine contractions increase

  • governed by a positive feedback mechanism

Describe the thyroid gland

• primary gland responsible for regulating metabolism in the body

• butterfly-shaped gland (two lobes, one on either side of the trachea) located directly below the larynx (voice box)

• two hormones produced:

  • thyroxine (T4)

  • calcitonin

WHat are the 2 hormones produced by the thyroid gland

• thyroxine (T4)

• calcitonin

Describe the parathyroid gland

• primary gland responsible for raising calcium levels in the blood

• four small glands attached to the posterior side of the thyroid

• hormone produced:

  • parathyroid hormone (PTH)

What hormone is produced by the parathyroid gland

• the parathyroid hormone (PTH)

Describe thyroxine (T4)

• hormone secreted by the thyroid gland that regulates metabolism

  • does so by increasing the rate at which the body metabolizes fats’, proteins, and carbs for energy

  • no specific target organs; stimulates cells of

    • the heart,

    • skeletal muscles,

    • liver

    • and kidneys

    • to increase the rate of cellular respiration

• Thyroxine also plays an important role in the growth and development of children by influencing the proper organization and differentiation of various cells into tissues and organs

How does thyroxine (T4) ,secreted by the thyroid gland, regulate metabolism?

• by increasing the rate at which the body metabolizes fats’, proteins, and carbs for energy

What are the targets for thyroxine (T4)

• no specific target organs

• stimulates cells of:

  • the heart

  • skeletal muscles

  • liver

  • and kidneys

  • to increase the rate of cellular respiration

Does thyroxine produce a negative or positive feedback loop?

• negative

Describe thyroxine’s (T4) negative feedback loop

1. Hypothalamus secretes the first tropic hormone, called thyroxine releasing hormone (TRH), into the anterior pituitary

2. the anterior pituitary releases the second tropic hormone, called thyroid stimulating hormone (TSH), into the thyroid gland

3. the thyroid gland is stimulated to produce thyroxine

4. high levels of thyroxine cause negative feedback by preventing the release of either TRH (at the hypothalamus) or TSH (at the anterior pituitary)

What is hypothyroidism

• having low quantities of thyroxine

Describe cretinism and how its caused

• low quantities of thyroxine produced during childhood (hypothyroidism) results in a condition called cretinism

• due to improper development of the thyroid gland

• physical symptoms include:

  • stocky and shorter than average stature

  • enlarged facial features

  • mental development delays\

• sufferers must receive regular hormonal injections early on in life

What happens when you have hypothyroidism during adulthood?

• hypothyroidism during adulthood results in multiple symptoms including:

  • constant fatigue

  • slow pulse rate

  • puffy skin

  • hair loss

  • easy weight gain

  • joint or muscle pain

  • increased sensitivity to cold

FOr thyroxine, what does the 4 mean in T4

• the synthesis of thyroxine requires iodine (The ‘4’ in T4 refers to the four iodine molecules in the hormones)

Relating to thyroxine (T4) what happens when you don’t consume enough iodine?

• insufficient dietary iodine means that thyroxine cannot be made

  • this means that there can be no feedback signal on the anterior pituitary to stop the synthesis of TSH

  • thus TSH will be constantly synthesized and continually stimulate the thyroid gland (even though no thyroxine made)

• this causes an enlargement of the thyroid gland called goitre

  • other than large swelling in the throat, additional symptoms may include:

    • difficulty breathing

    • difficulty swallowing

    • constant coughing

  • remission is possible with iodine supplements

What is hyperthyroidism

• overproduction of thyroxine is called hyperthyroidism

What happens when you get hyperthyroidism

• overproduction of thyroxine is called hyperthyroidism

• because metabolism is increased, symptoms may include:

  • anxiety

  • insomnia

  • difficulty concentrating

  • heat intolerance

  • irregular heartbeat

  • high blood pressure

  • excessive weight loss

• severe hyperthyroidism is a condition called graves’ disease

  • whereby sufferers display a characteristic protrusion of their eyes, thus interfering with vision

  • hyperthyroidism can be treated via medications or removal / irradiation of portions of the thyroid gland

What happens when calcium is too high in the blood

• when calcium in the blood is too high,

• calcitonin (from the thyroid gland) stimulates the uptake of calcium into bones

• and decreases kidney uptake from urine,

• thus lowering its concentration in the blood

What happens when calcium levels in the blood drop too low?

• if calcium levels in the blood drop too low

• parathyroid hormone (from the parathyroid glands) helps absorb calcium into the blood by:

  • breaking down bone

  • stimulating kidneys to absorb from the urine and also activating vitamin D

  • increasing absorption from food by the intestines (due to activated vitamin D)

Describe the adrenal glands

• adrenal glands are located above the kidneys and have two distinct regions each:

1. Adrenal cortex

• outer layer of adrenal glands

• pure endocrine cells

• secrete aldosterone and cortisol

2. Adrenal medulla

• central region of adrenal glands

• possess neurosecretory neurons

• secrete epinephrine and norepinephrine

What is secreted from the adrenal medulla portion of the adrenal glands and when do they get secreted?

• epinephrine and norepinephrine are secreted when the body encounters stresses (excitement, danger, anger, fear, injury, anxiety)

What is secreted from the adrenal cortex portion of the adrenal glands and describe that they do

• aldosterone

  • involved in osmoregulation and control of blood pressure

  • increase water and sodium reabsorption in the nephron

• cortisol

  • increases blood glucose levels when levels are low

  • via breakdown of proteins and fats

Describe the pineal gland and what is secretes

• located in the centre of the brain in humans

• secretes melatonin

  • helps regulate daily biorhythms

  • greater amount produced during darkness

  • targets hypothalamus, which helps body synchronize its biological clock (called circadian rhythm) with daily cycles of light and dark

• hGH (human growth hormone)

• Thyroxine (T4) mainly

• epinephrine

• norepinephrine

• The anterior and posterior pituitary glands differ fundamentally in how they synthesize and release hormones:

• the anterior lobe produces its own hormones in response to hypothalamic signals,

• while the posterior lobe acts as a storage and release site for hormones manufactured directly by the hypothalamus

GOOD FOR TEST

• since there is no thyroxine

• this means that there can be no feedback signal on the anterior pituitary to stop the synthesis of TSH

• thus TSH will be constantly synthesized and continually stimulate the thyroid gland

• causes an enlargement of the thyroid gland called goitre

  • large swelling in throat

  • difficulty breathing

  • difficulty swallowing

  • constant coughing

• remission is possible with iodine supplements

• symptoms you could get:

  • constant fatigue

  • slow pulse rate

  • puffy skin

  • hair loss

  • easy weight gain

  • joint or muscle pain

  • increased sensitivity to cold

• The anterior pituitary gland secretes two critical reproductive hormones known as gonadotropins: Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH), as well as Prolactin. Together, they control sexual development, gamete production, ovulation, and lactation

• because caffeine and ethanol inhibit the production of ADH

• This prevents your kidneys from reabsorbing water, leading to rapid bladder filling

• Epinephrine is the first-line treatment for anaphylaxis because it rapidly reverses the most life-threatening symptoms.

• It works by constricting blood vessels to raise dangerously low blood pressure and opening up the airways to restore normal breathing.

• It also stops the immune system from releasing further allergy-triggering chemicals

• early vertebrates, the pineal gland (often associated with an ancestral "third eye" or parietal eye) was directly sensitive to light.

• In modern animals, it no longer detects light directly in most species.

• Instead, it responds to light signals relayed from the eyes by altering the production of the hormone melatonin

• The hypothalamus connects the nervous and endocrine systems by acting as a translation bridge.

• It receives electrical signals from the brain and translates them into chemical messages—releasing and inhibiting hormones—which direct the pituitary gland to control the body's hormone-producing glands.

• Excessive TSH overstimulates the thyroid, causing it to overproduce T3 and T4.

• This leads to hyperthyroidism, which accelerates your metabolism.

• Conversely, too little TSH fails to stimulate the thyroid, leading to a severe drop in T3 and T4,

• which causes hypothyroidism, dangerously slowing down your metabolism.

What is the pancreas

• organ the size of a hand, located behind (posterior) the stomache and consists of two glands/portions

  • exocrine gland

  • endocrine gland

describe the two glands/portions of the pancreas

• exocrine gland

  • secretes digestive enzymes into the small intestine

  • makes up the majority of the pancreas

• endocrine gland

  • made of clusters of specialized endocrine cells called islets of langerhans

  • secrete insulin and glucagon

    • the primary hormones that regulate blood glucose levels

  • only 2% of the pancreas

Describe insulin

• secreted by beta cells in the islets of langerhans of the endocrine glands of the pancreas

• rise in blood glucose levels will trigger the release of insulin, leading to lowered blood glucose via:

  • instructing target cells (skeletal muscles, liver cells, adipose tissue) to uptake glucose from the blood

  • inhibit breakdown of glycogen in the liver

• other periphery effects

  • lowers fatty acid levels by promoting uptake and storage into the adipose tissue and inhibiting breakdown of fats’ unto fatty acids

  • lowers amino acid levels by promoting protein synthesis and inhibiting breakdown of proteins into amino acids

Describe glucagon

• secreted by alpha cells in the islets of langerhans of the endocrine glands in the pancreas

• drop in blood glucose levels will trigger the release of glucagon, leading to increased blood glucose via:

  • breakdown of glycogen to glucose in the liver

• other periphery effects:

  • breakdown of fats’ into fatty acids and proteins into amino acids

  • allows fatty acids and amino acids to be converted to glucose via gluconeogenesis

Describe the negative feedback loop of blood glucose

What are glucocorticoids

• glucocorticoids are a class of hormones secreted by the adrenal cortex to help raise blood sugar

• main glucocorticoid: Cortisol

  • breakdown of fats’ and proteins, into fatty acids and amino acids, respectively

  • synthesis of glucose from fatty acids and amino acids

  • reduce glucose uptake by body cells (except the cells in the central nervous system)

Describe the feedback loop that occurs when blood glucose is too low or epinephrine is secreted in response to stress

idk understand this

Describe the difference between hyperglycemia and hypoglycemia

• hyperglycemia

  • blood glucose that is too high

  • symptoms:

    • thirst

    • frequent urination

    • sugar in urine

    • fatigue

    • vision issues

    • weight loss

• hypoglycemia

  • blood glucose that is too low

  • symptoms:

    • nervousness

    • shaking

    • cold sweats

    • hunger

    • headaches

    • weakness

Describe diabetes mellitus

• characterized by elevated glucose levels and problem with either insulin production or action

• 3 classic symptoms:

  • frequent urination

    • abnormally high amount of glucose in filtrate of nephron

    • consequently, more water is pulled via osmosis from renal capillaries into tubules

  • increased thirst

    • due to need to replace excess excreted water

    • leads to increased water uptake

  • increased apetite

    • inability of insulin to help with glucose uptake into cells

    • leads to increased need to break down proteins and fats for energy, leading to further deficiencies that increase hunger do these nutrients

    • end result is weight loss

Describe the 3 classic symptoms of diabetes mellitus

1. Frequent urination

• abnormally high amounts of glucose in filtrate if nephron

• consequently, more water is pulled via osmosis from renal capillaries into tubules

2. Increased thirst

• due to need to replace excess water excreted

• leads to increased water uptake

3. increased appetite

• inability of insulin to help with glucose uptake into cells

• leads to increased need to break down proteins and fats for energy, leading to further deficiencies that increase hunger for these nutrients

• end result is weight loss

What are other symptoms and long term health effects of diabetes mellitus

• other symptoms

  • blurred vision

  • lethargy

  • nausea

  • vomiting

  • abdominal pain

• Long term health effects

  • loss of vision

  • kidney failure

  • hypertension

  • cardiovascular problems

  • damage to extremities in the body

What are the 2 types of diabetes

• different types of diabetes based on the reason for the failure of insulin to regulate blood sugar

• type 1 (aka juvenile diabetes)

• type 2

• gestational diabetes

Describe type 1 diabetes (aka juvenile diabetes)

• beta cells in the islets of Langerhans are destroyed and cannot produce insulin

• degeneration of beta cells can begin in infancy

• often diagnosed during childhood

• requires close monitoring and daily treatment of insulin

Describe type 2 diabetes

• reduced production of insulin or inability of insulin to bind to its receptors (called insulin resistance)

• develops during adulthood

• strongly associated with obesity

• controlled through diet and exercise

• oral drugs can be used to increase insulin production or encourage binding to its receptors

describe gestational diabetes

• 2-10% of pregnant women

• due to high blood glucose that develops during pregnancy

• temporary but can increase the risk of the mother and child developing diabetes later on in life