Endocrine System Flashcards
(26 cards)
Why do we need the Endocrine system?
Endocrine glands secrete chemical messages (hormones) into the bloodstream.
- The hormones are transported to different parts of the entire body to regulate homeostasis
- Slower, long-lasting response (compared to the nervous system)
The hormones act on target cells that have receptor proteins.
Hypothalamus
Hypothalamus = “master nerve control center”
nervous system
receives information from nerves around body about internal conditions
releasing hormones: regulates release of hormones from pituitary
Pituitary Gland
Pituitary gland = “master gland”
- endocrine system
- secretes a broad range
of “tropic” hormones -
stimulate other glands to
release other hormones
Posterior Pituitary
Posterior Pituitary:
Does not produce hormones but stores and releases ADH and oxytocin.
Anterior Pituitary
Anterior Pituitary: Hormone-synthesizing gland
Thyroid stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH)
Prolactin (PRL)
Human growth hormone (hGH)
Follicle-stimulating hormone (FSH)
Luteinizing hormone (LH)
Tropic Hormones:
Tropic Hormones: hormones that stimulate endocrine glands to release other hormones
Classes of Hormones: Peptide Hormones
- Peptide Hormone (protein-based, water soluble)
Hydrophilic, cannot cross the lipid bilayer (cell membrane)
Bind to receptor proteins in cell membrane
Triggers secondary messenger pathway
Activates internal cellular response
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Examples
Polypeptides: insulin & glucagon, antidiuretic hormone (ADH)
Glycoproteins: follicle-stimulating hormone (FSH)
Amines: epinephrine
Classes of Hormones: Steroid Horomone
- Steroid Hormone (Lipid-based, lipid-soluble)
Hydrophobic, can diffuse through the cell membrane
Bind to receptor proteins in cytoplasm and nucleus
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Example:
Cholesterol: estrogen, testosterone, aldosterone, cortisol
Control of Blood Glucose Levels (Alpha and Beta Cells)
Blood glucose levels are controlled by the islets of Langerhans cells in the pancreas
Alpha (α) cells – release hormone glucagon which causes the liver to breakdown glycogen 🡪 glucose
Beta (β) cells – release hormone insulin which causes the liver to convert glucose 🡪 glycogen
Control of Blood Glucose Levels (Low blood sugar)
Low blood sugar
(eg: after exercise or between meals)
Glucagon is released by the α cells
Stimulates breakdown of glycogen in the liver to glucose
Glucose released into the blood (and used to produce energy in cell respiration)
Blood sugar level increases
Control of Blood Glucose Levels (High-blood sugar)
High blood sugar
(eg: after a meal)
Insulin is released by the β cells
Stimulates uptake of glucose by muscle and fat cells from the blood
Glucose converted to glycogen for storage
Blood sugar level decreases
General Diabetes
Diabetes: The body does not produce enough or does not respond properly to insulin causing hyperglycemia (high blood sugar)
Without insulin, cells do not take in glucose and starve
Glucose is excreted in the urine, and subsequently more water is lost from the body
Type 1 Diabetes and Type 2 Diabetes
Type 1:
Pancreas fails to produce insulin. Autoimmune
Type 2:
Receptors stop responding to insulin so pancreas produces less insulin
Often diagnosed in adulthood due to diet, exercise, medication
Adrenal Glands (location)
2 located at the top of your kidneys.
Inner layer = Adrenal medulla
Outer layer = Adrenal cortex
Adrenal Medulla: Role
In response to a stressor, the adrenal medulla secretes epinephrine (adrenaline) and norepinephrine (noradrenaline).
Regulates the fight-or-flight response by increasing metabolism.
Epinephrine and norepinephrine trigger:
ARROW UP
Breathing rate
Heart rate
Blood pressure
Blood flow to the heart and muscles
Conversion of glycogen to glucose in the liver
Pupil dilation
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Blood flow to the extremities
Decrease digestion
ARROW DOWN
Glucocorticoids: Cortisol Effects
Increase blood glucose levels
Promotes the breakdown of muscle protein.
Promotes the breakdown of fat cells
Suppresses immune system
Epinephrine injections save lives
Used for anaphylactic shock (EpiPen) or during cardiac arrest to start heart
EPIPENS
Relax airway muscles making it easier to breathe (dilates airways; reduces swelling)
Reverses rapid decrease in blood pressure, causing an increase in heart rate and blood flow
Adrenal Cortex: Long-term stress response
Adrenal cortex produces stress hormones for long-term stress response
Glucocorticoids: cortisol
Mineralocorticoids: aldosterone
Glucocorticoids: Cortisol
In response to danger, the hypothalamus produces the corticotropin releasing hormone (CRH) that stimulates the anterior pituitary to secrete adrenocorticotropic hormone (ACTH). ACTH targets the adrenal cortex to release cortisol in order to increase blood glucose levels.
In short, Cortisol causes blood glucose levels to increase
Negative effects of cortisol
Sustained high levels of cortisol in chronic stress can cause:
Impaired thinking, damage to heart, high blood pressure, diabetes
Increased susception to infection
-Cortisol is a natural anti-inflammatory which suppresses the actions of the immune system
Mineralocorticoids: Aldosterone
The adrenal cortex secretes aldosterone which stimulates the kidneys to increase the absorption of sodium in the blood.
The increase of solutes in the blood, draws water from the kidneys, increasing blood pressure.
MEDULLA: Short-term stress response
Effects of epinephrine and norepinephrine:
Increased blood glucose
Increased blood pressure
Increased cellular metabolism (breathing and metabolic rate)
Change in blood flow patterns: increased blood flow to the heart and muscles, decreased blood flow to digestive and kidney systems
CORTEX: Long-term stress response
Effects of mineralocorticoids:
Retention of sodium ions and water, leading to increased blood volume and pressure
Effects of glucocorticoids:
Increased protein and fat metabolism, leading to increased blood glucose
Immune system suppressed
