Endocrine System Flashcards
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.
