Endocrine Central Control Flashcards
T/F: The glands are what give specificity to the endocrine system.
FALSE
Target cells impart specificity
Organs in the endocrine system are called ________.
Glands
How does the endocrine system differ from the nervous system?
- Route of communication: hormones via blood
2. Onset and duration of effects: delayed onset and prolonged effect
T/F: Most hormones are peptides.
TRUE
Steroids are _______ hormones and are all derived from ___________.
Lipid; cholesterol
What are the four steps of peptide hormone synthesis and secretion?
- Synthesis: preprohormone -> prohormone
- Packaging: Prohormone -> Hormone
- Storage
- Secretion
T/F: Steroid synthesizing cells can store steroids before releasing them.
FALSE
Describe the process of synthesizing a steroid.
- Peptide stimulus activates G protein receptor
- Adenyl cyclase increases cAMP -> activates PKA -> activates cholesterol esterase
- Cholesterol esterase frees intracellular cholesterol
- StAR shuttles cholesterol to mitochondria
- Various enzymes act on cholesterol in mitochondria and smooth ER
- Steroid is released (NOT STORED)
What are the three classifications of hormones?
- Peptides - small proteins
- Steroids - lipid hormones
- Amines - from tyrosine
Thyroid hormones are what classification of hormone?
Amines
T/F: Steroids and thyroid hormones are lipid soluble.
TRUE
What classification of hormones have the most diverse effects?
Amines
What is the difference between endocrine and exocrine glands?
Endocrine release into extra cellular fluid
Exocrine release via a duct/tube
T/F: Most of the hormones in the body are ___________ hormones.
Peptide
T/F: Human insulin and dog insulin will have the same chemical structure.
False
What is the purpose of adding sugar to peptides?
Slow down the breakdown of the peptide
T/F: Some peptides can be both hormones and neurotransmitters.
TRUE
Compare steroids with peptides.
Peptides: amino acids, water soluble, can be stored, variable in size
Steroids: cholesterol, lipid soluble, small, not variable
What are the largest sources of steroid production?
- Gonads
- Adrenal cortex
- Placenta
What is the main source of intracellular cholesterol?
LDL droplets
What are the catecholamines? Name the three common catecholamines and where they are made.
Peptide-like amine hormones
Norepinephrine: adrenal medulla
Epinephrine: adrenal medulla
Dopamine: hypothalamus
What are eicosanoids derived from?
Arachidonic acid
When are eicosanoids typically expressed?
Any cell when it is stressed
Aspirin inhibits the production of ___________.
Eicosanoids
T/F: Most hormones are released at a constant rate.
FALSE
Pulsating pattern
Hormone secretion can be broken down into two patterns: a __________ pattern (24 hours) and a _________ pattern (hourly).
Circadian; pulsating
What three factors control patterns of secretion?
- Plasma concentrations of a nutrient (ex. calcium regulation)
- Neural control
- Hormonal control
T/F: Peptides need carrier proteins to travel through the blood.
FALSE
Lipid soluble hormones need carrier proteins
What would be the benefit of a water soluble hormone using a carrier protein?
Small hydrophilic hormones (catecholamines) use carrier proteins to protect from degradation
What two organs are important for metabolism and excretion of hormones?
Liver and kidneys
T/F: Some hormones can be activated by metabolism while others are inactivated by metabolism.
TRUE
What are the three most important factors for a hormone response?
- Amount secreted
- How quickly its cleared from the blood
- Receptor expression
How do peptides and catecholamines act on a cell?
Bind to surface proteins.
Too large and lipophobic to pass membrane
__________ responses open ion channels; _________ responses alter cell activity.
Ionotropic; metabotropic
T/F: Ianotropic responses are often rapid, while metabotropic are sometimes delayed.
TRUE
Where are the receptors for steroid and thyroid hormones?
In the cell or nucleus
Describe a typical steroid response.
Steroid passes through membrane -> binds to receptor -> receptor-steroid complex enters nucleus and regulates transcription
T/F: Steroid responses are most often rapid.
FALSE
Delayed
T/F: There are no steroid receptors on the membrane.
FALSE
Some have been discovered but are rare
What are the two most important parts of the brain for endocrine function?
Hypothalamus and pituitary gland
What is found inside the hypothalamus?
Various clusters of neuronal cells all with separate functions.
Where is the anterior pituitary gland derived from?
Oral ectoderm from the roof of the mouth
Where is the posterior pituitary gland derived from?
Floor of hypothalamus
Hangs from infundibulum
What two hormones are released from the posterior pituitary?
Oxytocin and vasopressin
Made in hypothalamus (supraoptic and paraventricular nuclei); secreted in posterior pituitary
T/F: No hormones are produced in the posterior pituitary.
TRUE
Just secretion
What are the functions of oxytocin and vasopressin?
Oxytocin: smooth muscle contraction
Vasopressin: increase blood pressure
What is the relationship between the anterior pituitary and the hypothalamus?
Hypothalamus sends regulating hormones to anterior pituitary; typically stimulate releases of hormone from ant pituitary
Name the six hormones produced and released in the anterior pituitary.
- ACTH
- Thyroid stimulating hormone (TSH)
- Growth Hormone (GH)
- Luetinizing hormone (LH)
- Follicle stimulating hormone (FSH)
- Prolactin
7and8. POMC hormones
What are the two inhibitory hypophysiotropic hormones?
- Somatostatin - GH
2. Dopamine - prolactin
T/F: All hypophysiotropic hormones are peptides.
FALSE
What HPT hormone stimulates release of ACTH?
Corticotropin-releasing hormone
Which HPT hormone stimulates the release of LH and FSH?
Gonadotropin-releasing hormone
What is the difference between the short-loop and long-loop feedback systems for regulating pituitary and hormone activity?
Long-loop: target organ down regulates pituitary or hypothalamus
Short-loop: pituitary gland down regulates hypothalamus
T/F: Negative feedback mechanisms return hormone concentrations to normal.
TRUE
