CMB1004/L25 Endocrinology Flashcards
Describe hormonal control of body systems/tissues.
Hormones are secreted by specialised cells into the blood and act on specific receptors in target tissues
Describe gap junctions specificity.
Dependent on anatomical location.
Describe synaptic transmission specificity.
Dependent on anatomical location and receptors
Describe paracrine and autocrine specificity.
Dependent on receptors
Describe endocrine specificity.
Dependent on receptors
Define classically the endocrine system.
Endocrine cells within endocrine glands release hormones which are conveyed by the blood stream and act on distant cells
Why isn’t the classical definition of the endocrine system fully correct?
Hormones can have local and distant effects
Give 3 examples of non-classical endocrine tissues.
Kidney
Heart muscle
Endothelium
Platelets
Adipocytes
White blood cells
Define a hormone.
Chemical messenger, synthesised by specialised cells, secreted into the blood in small amounts which act on a specific receptor in target organs to regulate cellular function
Give 3 features of hormones.
High affinity
Synergistic
Permissive
Antagonistic
Competitive
What is a synergistic hormone? Give an example.
The effect of two hormones is greater than one alone
Thyroid and norepinephrine on heart rate
What is a permissive hormone? Give an example.
The presence of one hormone is necessary for another to have an effect
Thyroid and aldosterone on Na/K pumps in kidney
Give an example of antagonistic hormones.
Insulin and glucagon
Give an example of competitive hormones.
Epinephrine and norepinephrine
Give the 3 classes of hormones.
Steroids
Peptides
Amino acids
What are steroid hormones synthesised from?
Cholestrol
What is the most commonly produced type of hormone in the body?
Peptide hormones
What are amino acid hormones synthesised from? (which amino acid specifically?)
Tyrosine
When are steroid hormones released?
Immediately following synthesis
Describe the structure of steroid hormones.
Small hydrophobic/lipophilic
What kind of receptors do steroid hormones act on?
Intracellular receptors which bind to DNA
Describe the effects of steroid hormones. (2)
Slow and long-lasting
In which form are peptide hormones stored?
Preprohormones (inactive)
What kind of receptors do peptide hormones bind to?
Cell surface receptors then via 2nd messenger systems
When are amino acids hormones released?
Instantly following synthesis
What kind of receptors do amino acid hormones bind to?
Intracellular receptors
Cell surface receptors
Give 3 examples of 2nd messengers.
cAMP
cGMP
Ca2+
Diacylglycerol
IP3
Give an example of a rapid hormone response.
Transporter protein activation/inhibition
Give an example of short-term hormone response.
General metabolism
Neurotransmitter synthesis/release
Receptor sensitivity
Give an example of long-term hormone response.
Regulation of gene expression
Give an example of a 3rd messenger.
Dephosphoprotein
Phosphoprotein
Via protein phosphatase/kinase
What kind of receptors cause muscle relaxation?
Beta-2 adrenergic receptors
(cAMP pathway)
Give the 4 mechanisms of hormone release.
Continuous
Pulsatile
Circadian
Exocytosis on stimulus
Give the one mechanism of steroid hormone activation.
Post-release modification
Give 3 mechanisms of hormonal control effects.
Modification
Degradation
Receptor down-regulation
Termination of intracellular effects
Negative feedback
Give 3 substances which regulate negative feedback loops.
Metabolites
Hormone itself
Tropic hormone released by pituitary
