APK 2105C Lecture Notes - Lecture 47: Aldosterone, Adrenocorticotropic Hormone, Cortisol
Chapter 6, Lecture 3
Endocrine Glands & Hormones
• Control of plasma hormone levels
o Rate of hormone secretion
▪ Some hormones are secreted at a constant rate—don’t change much
• Thyroid hormones
▪ Other hormones are secreted in greater amts when signals are greater
• Signals are
o Neural
o Humoral
o Inhibitory
o Stimulatory
• Example
o Neural signal to increase hormone secretion
o Stress → neural signals → CRH → ACTH → cortisol →
target cells
• Example
o Humoral signals are
▪ Hormones
▪ Metabolites
▪ Ions
o Increased BG → secretion of insulin → more glucose
uptake → decreased BG → turns off beta cells
o Blood K → aldosterone secretion → increased K excretion
→ lower blood K → inhibits aldosterone secretion
o 3 contributing factors
▪ Rate of hormone secretion
▪ Amt of hormone transported bound to carrier proteins
• Protein bound hormone transport
o Hormones are water soluble or lipid soluble
o Hydrophobic hormones are transporter in blood bound to
carrier proteins
▪ Hydrophilic hormones do not need carrier proteins
• Are degraded very quickly in the blood
▪ Proteins are water soluble—able to go through the
blood
▪ Without protein, would form large blobs that block
blood flow
o Only the conc of unbound hormones affects the binding of
hormone to receptor
▪ There is a balance of bound and unbound
hormones
▪ Free hormones are able to bind to receptors
o Carrier proteins increase the half-life of hormones
▪ Keeps them in the blood longer
▪ Decreases rate of removal
▪ Binding to proteins keeps gives them more bulk
which allows for less degradation
▪ Rate of hormone removal
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