Animal Control Systems Flashcards
What are 2 basic ways of communication of cells ?
Chemical signals
Electrical signals
What are the different systems that allow cells to communicate?
- Endocrine system
- Nervous system (electrical system)
- Paracrine system
- Autocrine system
Endocrine system
Like broadcasting a signal (every single person in the city has the potential to hear/ receive that signal, but only the ppl that have radio on and are listening for that signal will receive it
Some gland somewhere in the body broadcasts a chemical signal and circulatory system spreads it out everywhere in the body and every cell in the body has the potential to receive it but only the ones listening for it will receive it
Have to have particular receptor molecule to detect signal
Nervous system
electrical system)
Opposite of endocrine system
If one cell wants to talk to another cell there needs to be a direct line or physical connection between them
Paracrine system
Sort of like endocrine system but on a much smaller scale
Like little loud speaker
Only cells in the nearby vicinity can hear but they need to have receptor molecule listening for that particular signal to hear it
Far away cells have no chance of getting it
Don’t go into circulatory system
Autocrine system
A cell is signaling it self
On way to shut down and limit own activity
Cells that are communicating/signaling with nearby cells of the exact same type
Ex- chemical synapse between neurons
What are the 2 broad classes of hormones?
water soluble
fat soluble
Water soluble
typically modified peptides or amino acids)
- Most hormones are water soluble (few lipid)
- Can’t pass through the lipid bilayer membrane (cell or nuclear membranes vesicles)
easy to be stored- can be stored in vesicles because they are polar they wont go anywhere because they cant break pass membrane (you need to aid them to pass membrane)
-Can float freely through blood and interstitial tissue
- There need to be receptor molecules that pass through the cell membrane in order for water soluble hormone to make affect on the cell
Receptor molecules are very specific but they may do different thing on inside of cell depending on what cell does what cell is
Ex- growth hormones, insulin, leptin, oxytocin
Lipid soluble
(steroid hormones)
Many peptide hormones(can be polar or nonpolar), most amine hormones(made of amino acids) and lipid hormones
All are lipid soluble
Can pass right through the lipid bilayer cell membrane and nuclear membrane (cannot be stored in vesicles)
Don’t need receptor molecule on the cell to get into cell
Need help to get to cell but once they get to cell they can freely pass through the membrane in and out into the nucleus
Ex- sex hormones androgens, estrogens, progestogens
Secretory cell
the ones that secrete the hormone
How are water soluble hormones delivered?
A gland broadcasts a chemical message (secrete hormone)
Have to be actively removed from secretory cell because they cant cross membrane on their own
Manufactured and put into vesicle which fuses with the cell membrane and get dumped into interstitial fluid from which the enter blood unaided
They enter blood from interstitial fluid because they follow concentration gradient (lots of hormone in fluid compared to blood so they go from high to low and leak into capillaries)
Must bind to surface receptor molecule on target cell
How are fat soluble hormones delivered?
Don’t have to be actively exported into interstitial fluid they just float out of secretory cell following concentration gradient into interstitial fluid
Leak into blood but need carrier proteins to do this because they are not water soluble
Carrier protein makes it water soluble so it can dissolve into the blood and flow around into the circulatory system like water soluble
Just floats into target cell
Leave carrier protein behind
Signal transduction for water soluble
Receptor molecules are GPCRs
Some receptor molecules open a channel and allow stuff in and out
Others do secondary messenger system where they bind to receptor molecules which sends a G protein to cell membrane to activate other membrane proteins
Signal transduction for fat soluble
No receptor molecule on target cell membrane
Hormone typically binds to free floating receptor in cytoplasm
Hormone Receptor complex floats into nucleus
Acts as transcription facts
how do hormones get distributed
hormones get distributed to tissues through the blood stream and each hormone affects target cells that have receptors for it
Ex- fat soluble can enter any cell freely but if cell isn’t listening for that lipid molecule it doesn’t matter it will just float in and out so cells must have receptor molecules for that specific hormones
parts of the Neuroendocrine system
The hypothalamus (part of the brain) major organ of the endocrine system
Right below Thalmus
Interface between nervous and endocrine system
It’s also interface between nervous and circulatory system
One of the Very few parts of the brain that have direct access to blood
Many of the hormones target the pituitary gland
Many pituitary hormones target other endocrine organs(tropic hormones)
Pineal gland- largely responsible for sleep patterns
Hypothalamus
Just like the brain is the command center of the nervous system it is the command system of the endocrine system
Just like some neural circuits do not involve the brain some endocrine circuits do not involve the hypothalamus
Posterior pituitary
Extension of the hypothalamus (same tissue)
Neurosecretory cells span form hypothalamus into posterior pituitary
Hormone secreted into interstitial fluid in posterior pituitary
Hormones taken up by blood in capillary bed
ADH- antidiuretic hormone target; kidney tubules stimulates retention of water
Oxytocin; target mammary glands and uterine contractions during childbirth
Anterior pituitary gland
Not an extension of the hypothalamus not the same tissue
Neural secretory glands cant extend in here
Neurosecretory cells in the hypothalamus secretes specific tropic hormone into interstsial fluid
Hormones are taken up by the blood in capillary bed in the hypothalamus
Blood transports hormones via portal vessels to the anterior pituitary gland
Hypothalamic tropic hormones then stimulate secretory cells to release other hormones into interstitial fluid
Hormones taken up by blood in capillary bed in the anterior pituitary
Blood transports them to the rest of the body
Anterior pituitary hormones
that are stimulated by hormones produced by hypothalamus
- follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
Target: gonads
- Thyroid -stimulating hormone (TSH)
Target: thyroid gland - adrenocorticotropic hormone(ACTH)
Target: adrenal cortex - prolactin
Target: mammary glands - melanocyte- stimulating hormone (MSH)
Target: melanocytes (melanin-Producing cells in skin) - growth hormone (GH)
Target: pretty much everywhere
Why is hormone signaling referred to as a cascade
Referred to as a cascade because one hormone triggers production of another and another
The hypothalamic-pituitary-thyroid (HPT) axis
he brain detects drop in thyroid hormones levels (T3 and T4):
In response, hypothalamus secrets thyrotropin-releasing hormone (TRH)
In response, anterior pituitary secretes thyrotropin (also called thyroid- stimulating hormone or TSH)
In response, the thyroid secretes thyroid hormones (T3 and T4)
These maintain blood pressure, heart rate, etc.
These close a negative feedback loop
T3 and t4 shut this all down the brain will no longer see a deficit of these hormones will stop signaling to anterior pituitary which will stop signaling TSH
The hypothalamic-pituitary-adrenal (HPA) axis
Under certain types of stress (e.g., low blood sugar):
Hypothalamus secrets corticotropin-releasing hormone (CRH)
In response, pituitary secretes adrenocorticotropic hormone (ACTH)
In response, the adrenal cortex secretes various corticosteroids(the production of the corticosteroids shuts down the whole cascade)
what are Two types of corticosteroids?
1. Glucocorticoids
• causes proteins and fats to be
broken down and converted to ACTH glucose
• causes immune system to be suppressed
2. Mineralocorticoids
causes kidneys to retain salts
and water
causes increased blood pressure and volume
Cortico- steroids
Note: Cortisol acts as both
