Chapter 18 Flashcards
Exocrine glands
Secrete their products into ducts that carry the secretions into body cavities, the lumen of an organ, or the outer surface of the body
include sweat glands, oil glands, mucus, and digestive glands
Endocrine glands
Secrete their products into the interstitial fluid surrounding the secretory cells rather than into ducts who then diffuse into blood capillaries then blood carries them to target cells throughout the body
What does the endocrine glands include?
Pituitary, thyroid, parathyroid, adrenal and pineal glands
Down-regulation
If a hormone is present in excess the number of target cell receptors decrease
Up regulation
When a hormone is deficient the number of receptors may increase
making the target cell more sensitive to a hormone
What other organs can secrete hormones?
Hypothalamus
thymus
pancreas
ovaries
testes
kidneys
stomach
liver
small intestine
skin
heart
adipose tissue
placenta
Circulating hormones
Pass from the secretory cells that make them into interstitial fluid and then into the blood
Local hormones
Act locally on neighbouring cells or on the same cell that secreted them without entering the bloodstream
Paracrines
Local hormones that act on neighbouring cells
Autocrines
Hormones that act on the same cell that secreted them
What are the three lipid soluble hormones?
- Steroid hormones
- Thyroid hormones
- Nitric oxide
Steroid hormones are derived from what?
Cholesterol
What is synthesized by attaching iodine to the amino acid tyrosine?
Thyroid hormones T3 and T4
What lipid soluble hormone is both a hormone and a neurotransmitter?
Nitric oxide (NO)
What are the three water soluble hormones?
- Amine hormones
- Peptide and protein hormones
- Eicosanoid hormones
How are Amine hormone synthesized?
By decarboxylating and otherwise modifying certain amino acids they are called amines because they retain an amino group
What are some examples of peptide hormones and protein hormones?
Peptide: antidiuretic and oxytocin
Protein: Growth hormone and insulin
What’s an example of Glycoprotein hormones?
Thyroid stimulating hormone
What are the two major types of Eicosanoids?
Prostaglandins and leukotrienes
How do water soluble hormone molecules circulate in the blood plasma?
In a “free” form
How do you lipid soluble hormone molecules move through the blood?
Via transport proteins
What are the three functions of the transport protein?
- They make lipid soluble hormones temporarily water soluble thus increasing their solubility in blood
- They retard passage of small hormone molecules through the filtering mechanism in the kidneys thus slowing the rate of hormone loss in the urine
- They provide a ready reserve of hormone already present in the bloodstream
Free fraction
The .1 to 10% of the molecules of lipid soluble hormones that are not bound to a transport protein that diffuse out of capillaries, bind to receptors and trigger responses
First messenger
When a water soluble hormone binds to its receptor at the outer surface of the plasma membrane
Second messenger
The first messenger causes production of the second messengers inside the cell where specific hormone stimulated responses take place
What is a common second messenger?
Cyclic adenosine monophosphate
Permissive affect
When a hormone will only work if there was Recent exposure from a second hormone
Synergistic effect
When the effect of two hormones acting together is greater than the sum of their individual effects