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Grade 12 > Endocrine System > Flashcards

Endocrine System Flashcards

1
Q

Endocrine system

A

composed of glands that produce and secrete hormones
-slower, longer lasting effects compared to the nervous system
- affects a broader range of cells

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2
Q

Endocrine glands

A

secrete hormones (chemical messengers) into bloodstream

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2
Q

Hormones

A

chemical messenger that has an effect on a specific cell/organ
- Examples: insulin (pancreas), testosterone (testes), adrenaline (adrenal glands), human growth hormone (hGH)
- There are over 200 known hormones in humans
- Hormones are classified based on their composition
- One hormone molecule can trigger release of hundreds-thousands of other molecules

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3
Q

Function of hormones

A
  • Growth
  • Metabolism
  • Immune response
  • Regulate blood pressure
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4
Q

Hormone Action on Target Cells:

A
  • Target cells have receptor proteins
  • Hormones are distributed by bloodstream
  • Hormones bind to specific receptors
  • Target cell receives the chemical message
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5
Q

Lipid based hormones

A
  • made of carbon-hydrogen ring structures (steroid hormones)
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6
Q

Water soluble hormones

A
  • dissolve in water
  • contain amino acid-type groups with polar side chains
  • protein hormones
  • Ex. epinephrine, hGH, thyroxine, and insulin
  • Cannot diffuse across cell membrane because it is a large polar molecule
  • Binds to receptor protein on surface of target cell
  • Triggers a series of reactions that amplifies the signal inside the cell
  • Called a cascade
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6
Q

Steroid Hormones

A
  • lipid based hormones (a.k.a. lipid soluble)
  • ex. testosterone, estrogen, cortisol
  • Can easily diffuse through cell membranes
  • Bind to receptor proteins inside the nucleus
  • Hormone-receptor activates gene expression and synthesis of specific mRNA
  • enter in through cell membrane and target nucleus
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7
Q

How steroid hormones work

A

Recall transcription produces mRNA for translation to a protein

  1. Hormone diffuses through membrane because it is lipid soluble
  2. Hormone binds receptor protein
  3. Hormone-receptor complex enters nucleus and activates gene (transcription occurs)

4-6. mRNA is translated to protein by the ribosome in cytoplasm

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7
Q

Cascade

A

One hormone molecule can trigger release of hundreds-thousands of other molecules
- Binds to receptor protein on surface of target cell
- Triggers a series of reactions that amplifies the signal inside the cell

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8
Q

Hormone Amplification

A

One hormone stimulates the release of many other molecules in the cell, ultimately a target molecule.

Ex. 1 molecule of epinephrine can produce millions of glucose molecules from glycogen storage

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9
Q

cAMP cascade

A

Epinephrine stimulates liver cells

Converts ATP to cyclic adenosine monophosphate (cAMP)

cAMP triggers an enzyme cascade
-high level of enzyme production

Enzymes breakdown glycogen into glucose, which enters bloodstream

Enzymes deactivate initial signal

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10
Q

Regulation of hormone signals

A

The Hypothalamus!!!!!!!!
- The hypothalamus receives sensory information from the nervous system
- After receipt of the signal, it secretes releasing hormones
- These are instructions for its neighbour, the pituitary gland, to release certain hormones

  • Hypothalamus controls the pituitary gland
  • Pituitary gland produces many hormones that stimulate endocrine glands throughout the body
  • Called tropic hormones (signaling target glands to release other hormones)
  • Together, the hypothalamus and pituitary gland maintain homeostasis
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11
Q

Nervous and endocrine system working together

A
  • Homeostasis depends upon the close relationship of the nervous(CNS/PNS) and endocrine system(Glands, hormones).
  • several chemicals act as both hormones and neurotransmitters (e.g., epinephrine)
  • Nervous system structures can secrete hormones just as glands do (e.g., hypothalamus)
  • Both systems have feedback loops
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11
Q

How the Hypothalamus and Pituitary work together

A
  • The hypothalamus secretes a releasing hormone into the anterior pituitary to telling it to release a hormone
  • Anterior pituitary releases 2nd hormone into bloodstream
  • Stimulates a target gland somewhere else in the body to release 3rd hormone into blood
  • 3rd hormone travels to another cell and produces an effect
  • Like many hormones, this system is controlled by negative feedback
  • Build up of 3rd hormone prevents further release of 1st two hormones
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12
Q

Controlling rate of metabolism

A
  • The pituitary is controlled by the hypothalamus via releasing hormones. The pituitary itself secretes tropic hormones
  • The hormones secreted by the thyroid gland help regulate the metabolic rate of the body through 2 hormones: thyroxine and calcitonin
  • This affects growth and development as well
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13
Q

Thyroid Gland

A
  • a.k.a the metabolic thermostat
  • turn up: hyperthyroidism
  • turn down: hypothyroidism
  • Located below the larynx
  • Made up of two lobes, one on each side of the trachea
  • each corner has parathyroid gland
  • anterior and posterior
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14
Q

Pituitary Gland

A
  • Made up of two lobes: anterior and posterior
  • 1 cm diameter
  • Attached to hypothalamus by neurosecretory cells
  • A neurosecretory cell is a neuron that releases a hormone at the final synapse. This hormone diffuses into the bloodstream through the capillaries

Releases tropic hormones for:
- Metabolism
- Growth
- Development
- Reproduction

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15
Q

Anterior Pituitary

A
  • At the front
  • Hormone synthesizing gland
  • Produces tropic hormones: TSH, ACTH, PRL, hGH, FSH, and LH
  • makes its own hormones, stimulating/tropic hormones
  • Releasing hormones from hypothalamus go to the anterior pituitary and stimulate/inhibit the release of tropic hormones into the bloodstream
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15
Q

Posterior Pituitary

A
  • At the back
  • Part of the nervous system
  • Does not produce hormones
  • Stores and secretes the hormones ADH and oxytocin, which are produced in hypothalamus
  • Antidiuretic hormone (arginine vasopressin) tells kidneys how much water to conserve.
  • Oxytocin = love hormone, released during labor/reproductive purposes
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16
Q

Regulating Growth

A
  • Human Growth Hormone (hGH)
  • Secreted by anterior pituitary
  • Affects almost every body tissue
  • Most effects are tropic
  • For example, it stimulate liver to secrete growth factor hormones
  • Stimulates growth of bone and cartilage, protein production
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17
Q

hGH and growth factors increase…

A
  • Protein synthesis
  • Cell division and growth (cartilage, bone, muscle)
  • Breakdown and release of fats
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18
Q

Gigantism

A

Cause: Pituitary gland secretes excessive hGH during childhood

Symptoms:
- large hands/feet
- thickening of toes/fingers
- prominent jaw/forehead
- deafness
- delayed puberty

Treatment: slowing production of hormone
- heart is monitored because it’s too big

18
Q

Pituitary Dwarfism

A

Cause: deficiency in hGH production in childhood

Symptoms:
- small body proportions
- slow growth

Treatment: hormone replacement therapy (but not successful)

19
Q

Acromegaly

A

Cause: overproduction of hGH in developed adults
- suddenly in adulthood, it can happen

Symptoms:
- softening and widening of bones and soft tissues
- enlarged feet and hands
- thick ribs
- headaches
- enlarged heart/kidneys

Treatment: drugs to lower or block production of hGH

20
Q

Regulating Metabolism

A
  • The Thyroid Gland a.k.a the metabolic thermostat
  • Located below the larynx
  • Made up of two lobes, one on each side of the trachea
21
Q

Negative Feedback with the Thyroid Gland

A
  1. Hypothalamus secretes Thyrotropin Releasing Hormone that stimulates the anterior pituitary gland.
  2. Anterior pituitary releases TSH into bloodstream.
  3. TSH targets thyroid gland.
  4. Causes thyroid to secrete thyroxine (T4) into bloodstream which stimulates increased cellular respiration in target cells.
  5. High levels of thyroxine (T4) cause negative feedback on the pituitary and hypothalamus, shutting
    down production of TSH or TRH
22
Q

Thyroxine (T4)

A
  • the 4 represents the 4 iodine molecules in the structure of thyroxine
  • T4 increases metabolism of fats, proteins and carbohydrates
  • Increase rate of cellular respiration in heart, skeletal muscles, liver and kidney cells
23
Q

Hypothyroidism

A

Due to low production of thyroxine

24
Q

Hypothyroidism In Adults

A
  • Could be caused by autoimmune disease, radiation therapy, medication
  • Weight gain: Thyroid producing less thyroxin, slows metabolism, don’t metabolize the food you eat as efficiently and you wont breakdown your fats in your body as fast as others

Symptoms:
- continually tired, feeling cold
- slow pulse rate
- Puffy skin
- hair loss
- Minor weight gain

25
Q

Hypothyroidism In Children

A
  • Due to failure of thyroid to properly develop (cretinism)
  • Results in stocky, short individuals w/ possible delays in mental development
26
Q

Hyperthyroidism

A
  • Overproduction of thyroxine
  • hypothalamus produces too much tRH
  • or anterior pituitary is producing too much tSH
  • Thyroxine stimulates metabolism = more ATP

Symptoms:
- Anxiety
- Insomnia
- Heat intolerance
- Weight loss
- Irregular heartbeat
- same in children and aults

27
Q

Goitre

A
  • Iodine in the diet (salt) is required to make thyroid hormones
  • Insufficient iodine = thyroxine is not made and there is no negative feedback signal to the pituitary to stop the secretion of TSH
  • this will make hypothalamus always release TRH and anterior pituitary will make more TSH
  • Too much TSH = extremely high stimulation of thyroid
  • Leads to enlargement of thyroid
  • will become inflammed
  • Great lake regions lack iodine in soil and water because it is fresh water, oceans have more iodine. Salt refiners add iodine to salt, making it iodized. Dairy and fish also contain iodine
27
Q

Graves’ disease

A
  • Same symptoms as hyperthyroidism
  • Immune system attacks thyroid
  • thyroid doesn’t know it’s producing T4, but it is, similar to hyperthyroidism
  • Also producing swelling around eyes
  • Can be treated with medication or removal of part of thyroid
  • The antibodies produced by the immune system act like TSH, and activates the thyroid to produce hormones
28
Q

Thyroid Gland and Calcitonin:

A

Calcitonin: Hromone secreted by Thyroid gland to Regulate calcium levels in the blood, which allows for bone cells to uptake the calcium from the blood
- antagonistic hormones are Calcitonin and PTH (if one is high, the other is low, act to reverse, if calcium is high calcitonin is released, is calcium is low, PTH is released)

Functions of calcium
- Bone/teeth formation
- Blood clotting
- Nerve conduction
- Muscle contraction
- vesicles for neurotransmitters

  • When blood calcium levels are high, calcitonin is released
  • Calcium is stored in the bones

If high blood calcium levels:
- Thyroid gland secretes calcitonin into blood
- Calcitonin allows bones to take in calcium, which is needed for bone development
- Body’s blood calcium levels will decrease back to normal

If low blood calcium levels:
- parathyroid glands secrete PTH (parathyroid hormone)
- PTH will act on bones (to release calcium from them, which can make them brittle, leads to osteoporosis
- Also acts on the kidneys, which help activate Vitamin D (Vitamin D helps the kidneys to absorb calcium so that it doesn’t go into urine and instead, to blood)
- Intestines also absorb calcium with their microvilli

29
Q

Parathyroid Hormone (PTH)

A
  • Produced and released by parathyroid glands
  • 4 small glands on the thyroid

Also regulates blood calcium levels:
- When blood [Ca2+] is low, PTH is released
- stimulates 1) bone to breakdown calcium phosphate, 2) kidneys reabsorb calcium from urine, and 3) intestines to absorb more Ca2+ from the digestive tract
- All of the above increase blood [Ca2+], which turns off PTH production

30
Q

Over secretion of PTH

A

Hyperparathyroidism causes bones to soften due to excess calcium released from the bone
- remember: its hyperPARAthyroidism

31
Q

Under secretion of PTH

A

Hypoparathyroidism causes muscle cramps due to lack of calcium for muscle contraction, it is all absorbed into bone.
- remember: its hypoPARAthyroidism
- muscles start to cramp because they need calcium to function
- all calcium is being absorbed into bones

32
Q

The Adrenal Glands

A
  • pair of organs that regulate stress response and blood sugar levels
  • Rest on top of the kidneys
  • connected to kidneys
  • deal with short and long term stress response
  • can deal with epinephrine and norepinephrine
  • can secrete cortisol

Composed of two layers:
- the adrenal medulla (inner layer) - short term stress
- the adrenal cortex (outer layer) - long term stress

  • The medulla and cortex produce hormones that are different in structure and function
33
Q

Adrenal Medulla (Inner Adrenal Cortex)

A
  • In this case it acts as a hormone when released by the adrenal medulla
  • Regulates Short-term Stress Response
  • connection between endocrine system and nervous system
  • short term stress response affects also the nervous system because since epinephrine and norepinephrine are released, they are hormones and neurotransmitters that affect it

Adrenal medulla produces:
- Epinephrine (adrenaline)
- Norepinephrine (noradrenaline)

  • These hormones regulate “Fight, Flight or Freeze ” response
  • Cause similar effects to the Sympathetic (autonomic) Nervous System
  • Norepinephrine can act as both a neurotransmitter (messenger between neurons) and a hormone (affects activity of cells directly)
34
Q

When you are jump scared…

A
  1. Stimulus occurs, the Amygdala interprets images and sound as stressful, which sends distress signal to hypothalamus
  2. Hypothalamus activates the sympathetic nervous system via autonomic nerves, carrying signal from hypothalamus to adrenal medulla
  3. Neurons stimulate adrenal medulla to secrete epinephrine and norepinephrine
  4. Triggers stress response – increase body activity

Results:
- Rapid release and effects due to nervous system control
- Effects last many times longer than nervous system effects

35
Q

Short Term Stress Response

A
  • Increased heartbeat and blood pressure
  • Rise in blood glucose levels
  • Energized muscles
  • Dilated pupils
  • ‘Fight, Flight or Freeze’
  • Epinephrine is used because:
  • Allergic reaction: hypotension low bp, low blood flow. Epinephrine constricts veins, heartrate increases, also relaxes the muscles of the airways so you can breathe
36
Q

Adrenal Cortex

A

Regulating Long-Term Stress Response
- Adrenal cortex produces:
- Glucocorticoids (↑ blood sugar)
- Mineralocorticoids (↑ blood pressure)
- Glucocorticoids cause suppression of calcium absorption, slow wound healing, muscle weakness.
- Mineralocorticoids increase sodium absorption in the blood

  • They trigger sustained physiological stress responses
37
Q

Cortisol

A
  • a glucocorticoid stress hormone
  • most abundant glucocorticoid
  • Produced via the long-term stress response
  • Releasing hormone stimulates secretion of adrenocorticotropic hormone (ACTH) from the anterior P.G.
  • Causes adrenal cortex to release the stress hormone cortisol
  • Cortisol breaks down muscle protein into amino acids
  • Those Amino acids are then removed from the blood by liver
    Then used to make glucose
    Glucose is released to the blood
  • It also breaks down fat cells
    Releases glucose
  • Increased levels of cortisol in the blood causes negative feedback that suppresses ACTH and its release
  • Cortisol reduces allergic/inflammatory immune system responses caused from damaged tissues
  • Raises blood glucose levels
38
Q

Cortisone

A
  • Cortisol reduces allergic/inflammatory immune system responses caused from damaged tissues
  • Cortisone is a drug given in many instances to reduce inflammation or allergic response
  • Cortisone injections are sometimes given to patients with arthritis to help reduce the inflammation.
39
Q

Aldosterone

A
  • Main mineralocorticoid
  • Stimulates kidneys to increase Na+ absorption to blood
  • Increase [] of solutes in blood
  • Draws more water from kidneys
40
Q

Addison’s Disease

A
  • Due to damage of adrenal cortex
  • Insufficient glucocorticoid and mineralocorticoid secretion
  • Results in low blood sugar (hypoglycemia), sodium and potassium imbalances, and weight loss
41
Q

The Pancreas

A
  • pancreas functions in the digestive system (produces enzymes to breakdown food) and endocrine systems (hormones: insulin and glucagon)
  • Connected to the intestines by the pancreatic duct
  • Over 2000 clusters of endocrine cells, called the islets of Langerhans, scattered throughout the pancreas
42
Q

Islets of Langerhans

A
  • Over 2000 clusters of endocrine cells, called the islets of Langerhans, scattered throughout the pancreas

secret antagonistic hormones:
- insulin (secreted by beta cells) lowers blood glucose by making target cells more permeable to glucose

  • glucagon (secreted by alpha cells) increases blood glucose by stimulating the liver to convert glycogen to glucose
  • Recall: calcitonin and PTH are also antagonistic hormones (opposite effects)
43
Q

Diabetes Mellitus

A
  • beta cells of pancreas deteriorate and fail to produce adequate amounts of insulin
    OR
  • Cells do not properly to react to the insulin and the blood sugar level rises above normal
  • This is known as hyperglycemia

There are two forms of diabetes mellitus
- Juvenile
- Adult or late-onset diabetes

44
Q

Type 1 diabetes

A
  • Juvenile diabetes
  • diabetes Mellitus
  • before the age of 20 years
  • caused by early degeneration of the beta cells in the pancreas
  • immune system attacks and destroys the beta cells
  • Daily injections of insulin are necessary to replace the missing insulin
  • also known as insulin dependent
  • Injections are administered by the patient subcutaneously, why?
  • since insulin is a protein hormone and would be digested if given orally
45
Q

Type 2 Diabetes

A
  • Adult or late-onset diabetes
  • Diabetes Mellitus
  • Around 90% of diabetics develop the condition as adults.

Due to two potential factors:
1.) Cells in the body do not respond properly to insulin, not allowing them to take in glucose for metabolism
2.) Reduced insulin output by the beta cells of the pancreas

  • Sulfonamide drugs are also prescribed to stimulate the beta cells to produce a little more insulin.
  • Other drugs allow for cells to be more sensitive to insulin and respond properly to the presence of insulin
  • Not necessary to give insulin and so this condition is also known as non-insulin dependent diabetes. can increase insulin production by pancreas with drugs
46
Q

Reproductive System and Sex Hormones

A
  • Male and females both have gonads (testes and ovaries) that produce reproductive cells.
  • Males produce sperm
  • Females produce eggs
  • Sex hormones – control the development and function of the reproductive system or secondary sex characteristics
47
Q

What type of hormone causes the fastest reaction?

A

protein/water-soluble hormones
- because the hormone only attaches to a receptor that causes a cascade event
- That’s why epinephrine is used as adrenaline, because it’s so quick
- targets all cells that has that specific receptor on it

48
Q

Hypothalamus hormones vs. pituitary glands hormones

A

hypothalamus
- releasing hormones
- goes to pituitary gland

pituitary gland
- releases tropic/stimulating hormones
- goes through blood stream to go to specific glands
- glands release hormones

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