T1 L1 Intro to the endocrine system Flashcards
What is the endocrine system?
System of ductless glands which secrete chemical messengers into the blood
Describe the nervous system
Cells release a chemical messenger & grow towards each other Rapid Focused Precise Communication between individual cells
Describe the endocrine system
Cells release chemical messenger into carrier medium
Very slow
Sustained contraction
Communication between groups of cells
What does the pineal gland do?
Regulates sleep-wake cycle
What functions does the pancreas have?
Exocrine: secretes digestive enzymes into GI tract
Endocrine: secretes insulin into the blood
What is the medulla involved in?
Stress response
What is the cortex involved in?
Stress
Sodium homeostasis
Glucose homeostasis
Describe the method of steroid hormone receptors
1) Hormone crosses cell membrane
2) Binds to cytoplasmic or nuclear receptor
3) Hormone receptor complex then binds to hormone-response element of DNA
4) Influence gene transcription
Describe the method of G-protein coupled receptors
1) Hormone binds to 7 transmembrane receptor
2) Synthesis of second messenger e.g. IP3 or cAMP
3) Second messengers phosphorylate intracellular regulatory proteins
4) Influence cellular activity e.g. smooth muscle contraction
Describe tyrosine kinase receptors
Membrane-bound enzyme which is a single strand of protein
Often 2 receptors must be present for hormone action (dimerised receptors)
Receptor acts as an enzyme to phosphorylate tyrosine components of intracellular regulatory proteins
What are tyrosine kinase receptors involved with?
Involved with growth & development
Describe the characteristics of peptide hormone
Water soluble Not orally active Rapid onset of action Short plasma half life Short duration of action
Describe the characteristics of steroid & thyroid hormones
Poorly water soluble Orally active Slow onset of action Long plasma half life Long duration of action Crosses cell membrane
What receptors do peptide hormones act on?
Membrane-bound receptors
What receptors do steroid & thyroid hormones act on?
Intracellular receptors
