Communication by hormones:
endocrine
Information Processing
Signal transduction:
- Sensory cell (have signal receptors)
- receives external signal and transduces information to an internal signal
- Cell to cell signal (hormones)
- released by the sensory cell travels throughout plant
- Target cell (have hormone receptors)
- receives signal and initiates response
5 Chemical Signals
- Neural signals: diffuse a short distance between neurons
- Neuroendocrine signals: are hormones released from neurons
- Endocrine signals: are hormones carried between cells by blood or other body fluids
- Paracrine signals: diffuse locally and act on nearby cells
- Autocrine signals: act on the same cell that secretes them
Integration of hormones and neurons:
Opportunity for feedback:
Opportunity for feedback: feedback inhibition (negative feedback) → homeostasis
What are the 3 pathways and what do they each have?
- Endocrine pathway: has hormone
- Neuroendocrine pathway: has neurohormone
- Neuroendocrine-to-endocrine pathway: has both neurohormone and hormone
Actions of Hormones:
2 fundamentally different pathways are:
water soluble (hydrophilic) hormones and water insoluble (lipophilic hormones)
Hydrophilic hormones are and have?
Hydro: Peptides and Polypeptides, Amino Acid Derivatives
Has a Membrane receptor: intracellular signal transduction (second messengers)
Lipophilic hormones are and have?
Lipo: Steroids
Has a intracellular receptor (nuclear receptor)
Steroid Hormones examples:
- cortisol: stress response
- anabolic steroids - muscle growth
- sex steroids: estrogenes, testosterone
- Aldosterone ; Na+ resorption in kidney
other water insoluble (lipophilic) hormones (same mechanism)
- retinoid acid
- thyroid hormone
- Prostaglandins (paracrine acting)
- juvenile hormone (insects)
Actions of Steroid hormones
Example used for answers: hormone stimulates gene expression (up-regulation)
The steroid hormone will…
The steroid hormone will…
- diffuse through plasma membrane
- in cytosol, bound by receptor
- move into nucleus
- hormone/receptor complex binds to response element
- turn on gene expression
- proteins are translated in the cytosol
Some hormone suppress gene expression: binding to element stops what? this leads to what
Transcription
- So it will turn off gene expression
- and protein are not translated in the cytosol
What are target cell for steroid hormone:
- Target cell for steroid hormone: cells that have intracellular receptor
- Hormones act in extremely small amounts
- very strong binding to receptors
- often bind as dimers:
What are the two identical and different proteins/hormones
Two identical proteins/hormones: Homo-dimers
Two different proteins/hormones: hetero-dimers
Insect example: Insects remodels to emerge as adult moth
The growth by molting is controlled by which hormone:
Which hormone causes larva-larva molting
- larva grow by molting: controlled by hormones:
- ecdysone: triggers each molting
- Juvenile hormone: causes larva-larva molting
Frequently, hormones work together:
different combinations can have very different effects (turn on different genes etc)
Hydrophilic Hormones examples:
They are what?
What hormone is it?
Peptide hormones
- growth hormone (GH): organ and muscle growth
- growth hormone release hormone
Many peptides hormones are controlled by what?
examples? What are they essential for? What do they do?
controlled by release factors.
- antidiuretic hormone (reabsorption of water)
- insulin, glucagon (control blood sugar)
- leptin (regulation of lipid storage)
- adipokinetic hormone (insects, fat mobilization)
- all the following are essential for homeostasis.
- They keep the animals in normal condition
other water soluble hormones (same mechanism)
- adrenaline (= epinephrine: “flight or fight”)
- melatonin (sleep, internal clock)
What does adrenaline do?
- dilates pupils (vision increased)
- pain sensitivity decrease
- heart rate increases
- metabolic rate increases
- oxygen increases
- glucose increases
Where are they released? What effects do they have?
centrally released, different effect on different cells
They have different what? They always have ___?
different adrenalin receptors
but always a membrane protein
Phosphorylase is activated by?
Binding of adrenalin to a membrane receptor lead to what?
by a protein kinase
should lead to activation this kinase (phosphorylase kinase)
Steps for adrenaline
- Adrenaline binds to receptor
- G protein is activated
- Adenyl cyclase is activated: catalyzes formation of cAMP (second messenger)
- Phosphorylase kinase
- Phosphorylase is activated
- Glucose is produced from glycogen
