Endo 1 Flashcards
In order for indirect chemical messenger to work it requires ___________ and ____________ of receptor
Presence
Specificity
Paracrines
- diffuse short distance through extra cellular fluid
- binding to adjacent cells
Hormones
Released into bloodstream by endocrine cells
Can neutrons release hormones?
Yes - neurotransmitters
Target cells
Express receptors for the hormone
Responsible for hormone function
Functions of the endocrine system
Metabolism
Growth and development
Reproduction
Response to stress
Water and electrolyte balance
Digestive and circulatory systems
5 ways to regulate hormone secretion
- Neurotransmitters
- Other hormones
- Metabolites (glucose/ AA)
- Ions ( potassium / calcium)
- Hormonal feedback
Hydrophilic hormones
Water soluble
Lipophobic
Cannot cross plasma membrane
Ie. Peptide hormone, protein hormone and catecholamines
Hydrophobic hormones
Not water soluble
Lipophilic (lipid soluble)
Readily cross plasma membrane
Is. Steroid and thyroid hormones
Classify hydrophilic hormones
Membrane solubility :
Synthesis:
Release:
Transport in blood:
Not lipid soluble
In advance (stored)
Exocytosis
Dissolved
Classify hydrophobic hormones
Membrane solubility :
Synthesis:
Release:
Transport in blood:
Lipid soluble
On demand
Diffusion
Bound to Carrier proteins
Name a direct and indirect form of cell to cell communication
Direct physical link = gap junctions
Indirect = via chemical messenger
Intercellular receptors
Cytoplasmic, cytosolic or nuclear
Bind hydrophobic or lipophilic
Directly alters gene transcription
Slower responses
Membrane bound receptors
G protein linked receptors
Ligand gated ion channels
Bind hydrophilic/ lipophobic
Rapid responses
5 steps of intercellular signalling (hydrophobic)
Hormone diffuses into cell
Hormone binds to receptor
Hormone/receptor complex binds to the HRE on DNA
MRNA coding for specific protein is made
Specific protein is made in cytosol
