Chapter 11 Flashcards
What are Hormones?
Chemical Messengers secreted by endocrine glands or tissues into the blood. Travel everywhere blood goes but they only affect “Target Cells” (Cells with receptors)
What is the Endocrine System?
Composed of the glands and cells that secrete hormones.
What does the Endocrine System help regulate?
- Growth and Development
- metabolism and H2O balance
- Reproduction and stress responses
What is Endocrinology?
The study of the Endocrine System and the diagnosis and treatment of its disorders
What is the difference between Endocrine and Exocrine Glands?
Exocrine Glands –> Release their secretions to a tissue surface by way of ducts
Endocrine Glands –>Ductless and release their secretions into the blood
What are the differences between the Endocrine System and the Nervous System?
Endocrine System: Communicates by chemical signals only; Slower to respond and stop to a stimulus, Hormones go everywhere the blood goes, adapts relatively slowly, sometimes widespread affects
Nervous System: Communicates by chemical and electrical signals, responds and stops quickly to stimulus, Targets a specific organ, adapts quickly, and usually has local effects.
What do the Nervous System and Endocrine System have in common?
- Some chemicals such as Norepinephrine and dopamine function as hormones and neurotransmitters
- Some hormones are secreted by specialized neurons called neuroendocrine cells which functionally belong to both the endocrine and nervous system.
- Hormones and neurotransmitters may have similar effects on the same target cells (e.g. norepinephrine and glucagon on liver)
- Neurons sometimes trigger hormone secretion
- Some hormones may stimulate or inhibit neurons
- Regulate each other
Hormones are classified into 3 groups based on _______?
Structure
What are the 3 groups of Hormones
1) Steroid Hormones –> Lipids synthesized from cholesterol, and share its basic structure of 4 organic rings with varied side groups. (e.g. Testosterone and estradiol)
2) Monoamines –> Small molecules synthesized from the amino acids tyrosine and tryptophan. (e.g. Thyroxine and epinephrine)
3) Peptide Hormones –> Chains ranging from 3 to more than 200 amino acids long; ones with 50 or more amino acids or longer are considered proteins and some glycoproteins (proteins with a carbohydrate attached); Oxytocin is a small peptide hormone; insulin is a protein.
Peptide hormones and most monoamines are ________? (Hydrophobic or Hydrophilic?)
Hydrophilic, unable to pass into target cell
Steroid Hormones are _____? (Hydrophobic or Hydrophilic)
Hydrophobic, readily pass into cell
What Hormone type Transcribes Genes?
Steroid Hormones
What kind of feedback control does hormonal control rely and what would be an example?
Negative Feedback - Blood Glucose regulation
What 2 organs usually take up Hormone Clearance via degradation or excretion?
Liver and Kidneys
What is an example of a hormone that is removed quickly?
Growth Hormone
What is an example of a hormone that stays in blood longer?
Thyroid Hormone
The Hypothalamus is attached to the posterior pituitary by the _________?
Infundibulum
What does the Hypothalamic Nuclei do?
- Synthesizes Oxytocin and antidiuretic hormone
- Transport down fibers for storage in posterior pituitary (sends electrical signals to stimulate release)
What is the pituitary gland?
- Important link in the neural and hormonal regulation of homeostasis
- It is an endocrine gland controlling multiple body functions
- Also known as the “Hypophysis”
The Pituitary gland is small but grows how much larger during pregnancy?
50%
How is the Pituitary Gland divided?
Anterior –> Develops from a pouch in the roof of the embryonic Pharynx (Throat).
Posterior –> Arises as a down-growth from the hypothalamus and retains its connection to the brain throughout life
What is the Hypophyseal Portal System?
Network of small blood vessels which connects the Hypothalamus to the Anterior Pituitary Gland. The Hypothalamus secretes chemical signals into the capillaries at its end of the portal system; these signals travel a short distance to the anterior pituitary. Here they leave the bloodstream through a 2nd capillary network and tell the anterior pituitary what to do.
The Hormones synthesized by the anterior pituitary gland are?
Peptide Hormones
What are the 6 Hormones Synthesized by anterior pituitary gland?
1) Follicle-Stimulating Hormone (FSH)
2) Luteinizing Hormone (LH)
3) Thyroid-Stimulating Hormone (TSH) - AKA Thyrotropin
4) Adrenocorticotropic Hormone (ACTH) - AKA Corticotropin
5) Prolactin (PRL)
6) Growth Hormone (GH) - AKA Somatotropin
What is FSH?
Follicle-Stimulating Hormone
- Stimulates maturation of follicles containing eggs
- stimulates follicles to secrete estrogen
- helps regulate ovarian and menstrual cycles
- in males, stimulates production of sperm
What is LH?
Luteinizing Hormone
- Stimulates ovulation in females (The follicle left behind after ovulation develops into a yellowish structure called corpus luteum)
- Stimulates corpus lutem to secrete progesterone (Maintains lining of uterus during pregnancy)
- Stimulates testes to secrete testosterone
What is TSH?
Thyroid-Stimulating Hormone
- Stimulates Thyroid gland to secrete thyroid hormone (necessary for regulation of metabolism)
What is ACTH?
Adrenocorticotropic Hormone
- Stimulates adrenal cortex to secrete hormones called “Glucocorticoids” which are important in glucose, fat and protein metabolism
What is PRL?
Prolactin
- Stimulates mammary glands to secrete milk
- In males, it makes testes more sensitive to LH
What is GH?
Growth Hormone
- Promotes Tissue Growth by mobilizing energy from fat, raising levels of calcium and other electrolytes, and stimulating protein synthesis, mitosis, and cellular differentiation
- Has widespread effects on the body and are most conspicuous during childhood and adolescence, but important for tissue maintenance and repair throughout life.