Regulatory Systems Flashcards
Homeostasis
- life process that maintains a balanced/orderly system with changes to enivornment
- constant internal environment that requires energy source
- to regulate, cells must be able to detect change instate, process info and respond
Conformers
- cold blooded, internal state change because of environment
Contact communication
Cells can make physical contact in a way that allows molecules on the surface of one cell to interact with receptors on the other cell. Cells in a tissue specialize and maintain their cooperative behaviours partly through direct contact. Cells in the immune system display antigens from foreign organisms to recruit other immune cells to mount an attack. (one to one, local)
Paracrine communication
Cells may release signal molecules into the interstitial fluid around them. These then diffuse outward and are picked up by receptors on neighbouring cells. Many growth factors that control cell reproduction, immune responses and healing are paracrine signals. Paracrine signaling is local and non-specific. (one to many, local)
Synaptic communication
Cells may release chemical signals only in the vicinity of one or a few neighbouring cells. These substances then diffuse across the narrow gap (synapse) and stimulate only the specific target cell. Neurons, which are long thin cells, use synaptic signaling to carry information from one location in the body to very specific targets in another location. (one to one, remote)
Endocrine communication
Cells in one area of the body may release signal molecules, called hormones, directly into the blood. These molecules are then carried to every cell in the body, where they may be picked up by receptors. (one to many, remote)
‘crine’
secretion (release chemical signal molecule)
The Model:
Stimulus, Receptor, Processor (transduction), Response/Effect, -ve feedback
-ve feedback
can reduce intensity of stimulus/ change in environment
ligands
molecules that produce signal by binding to target protein
Normal results
- physical change, chemical change, secretion
Signal
A molecule released by another cell, or physical change (pressure, light, charge). Small molecules such as fatty acids, amino acids, short polypeptides, steroids and oligio saccharaides are common signals
Receptor
Signal only has meaning if other cell has receptors to bind. Generally a transmembrane protein with active site for signal molecule part outside membrane. The part inside has enzymatic function that is activated when outside part has soemthing bind to active site. Receptor depends on solubility of signal molecule (lipid=diffuse)
Processor
The enzyme part of a receptor protein changes molecule inside cell, starting more changes. Cascade reactions for enzyme. First, new small signals = 2nd messengers which activate more molecules.
Response
After cascade, funcitonal enzymes are activated or inhibited and will carry out new metabolic processes
Effector
Cell may change and alter state of body, contract, synthesize new things or secrete. Can produce signal to other cells, -ve feedback.
g-protein/cAMP transduction (epinephrine)
- Signal molecule binds to receptor protein
- Enzymatic end in cytoplasm is activated by the binding
- Enzyme catalyzes the replacement of GDP by CTP from krebs on G-protein
- Activated g-protein travels and binds to membrane bound enzyme adenylyl cyclase
- Adenylyl cyclase active converts ATP to cAMP
- G-protein catalyzes GTP to GDP, dissociate cyclase
- cAMP binds and activates protein kinase
- Primary protein kinase actives more kinase
- After cascade, enzyme is activated
Transduction Pathway
the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events
Advantages of the transduction pathway
- exponential gro3wth from small signal
- small 2nd messenger diffuse to target enzyme faster than large enzymes could diffuse to receptor for activation
- multiple pathways in different cells can be activated by same signal and receptor
- more control by more steps, regulation
Protein kinase
adds phosphate groups to certain proteins
Hormones
- chemical messages that are relased by endocrine glands, travel in the blood and act on a target organ, allow messages to travel through the body for homeostasis
- lipid and protein hormones
Lipid hormones
Cross cell membranes and bind to receptors in cytoplasm or nucleus. Act as a transcription factor and activate gene expression. Chemically, lipids are steroids because they are libid soluble.
Protein hormone
Bind to receptors embedded in membrane as they are too large or polar to diffue through. Can trigger signal transduction pathways that can cause many respomses. Are hydrophobic, bind on surface ex. Epinephrine
non target cells
lack receptors
target cells
respond, have membrane receptor made from genes that are transcribed and translated
regulatory transcription factor
receptor hormone complex that binds to receptor and mRNA
Stimulus Stress:
Long term:
Effector: ACTH that secretes cortisol, break down glycogen and burn more energy
Short term - epininephrine
Effector: fight or flight
Blood Calcium
Stimulus: low blood calcium
Receptor/Processor: Parathyroid that secretes PTH
Effector 1: increased calcium absorption in intestine
Effector 2: kidney reabsorption of calcium, secretion phosphate
Effector 3: osteclasts dissolve calcium phosphate crystals in bones, releasing calcium
Response: increased blood calcium
Temperature Regulation
Stimulus: low blood temp
Receptor: detection by thermostatic cells
Processor 1: Hypothalamus, TRH
Processor 2: Anterior Pituitary, TSH
Processor 3: Thyroid, T3 T4
Effector: Muscles
Response: increased metabolic rate, more heat
Multiple feedback loop
- evolutionary advantage of multi step process or or haivng lots of endocrine organs communicating with others
- reduce ampiltude of oscilations and have steadier state
Antagonist regualtion of blood sugar
- food - increases blood sugar
- blood sugar increases insulin
- glucose from insulin takes up glycogensis fat storage
- blood glucose drops (exercise/starvation)
- glucagon increases, for glycogensis fat break down
If you eat something that is harder to digest in the longterm energy, and don’t release as much insulin, the drop will be less and give you a better chance to balance hormones.
Antagonists
- Blood calcium/phosphate (parathyroid/thyroid)
- thyroid hormones (TRH-TIH)
- blood pressure (ANH/RAAS)
- heart rate (epinephrine/acetylcholine)
Adipose tissue
fat storage tissue
Hormone: ACTH
Hormone: ACTH
Endocrine Organ: Anterior Pituitary
Target Hormone: adrenal gland
Function: secrete cortisol
Hormone: Cortisol
Hormone: Cortisol
Endocrine Organ: adrenal gland
Target Hormone: various, adipose liver
Function: metabolize nutrients for energy, supports long term stress
Hormone: Epinephrine
Hormone: epinephrine
Endocrine Organ: adrenal gland
Target Hormone: various, liver
Function: short term stress, break dowm glycogen
Hormone: PTH
Hormone: PTH
Endocrine Organ: parathyroid gland
Target Hormone: intestines/kidney/bones
Function: increase blood calcium
Hormone: TRH
Hormone: trh
Endocrine Organ: secreted but the hypothalamus
Target Hormone: anterior pituitary
Function: cause anterior pituitary to release TSH
Hormone: TSH
Hormone: tsh
Endocrine Organ: anterior pituitary
Target Hormone: thyroid
Function: release T4/T3
Hormoe: T4/T3
Hormone: T4/T3
Endocrine Organ: anterior pituitary
Target Hormone: thyroid
Function: increase basil metabolic rate
Hormone: Insulin
Hormone: Insulin
Endocrine Organ: Pancreas
Target Hormone: liver, skeletal muscle (keeps it), and adipose tissue
Function: glucose uptake, glycogenesis, fat storage
Hormone: Glucagen
Hormone: glucagen
Endocrine Organ: pancreas
Target Hormone: liver, adipose tissue
Function: glycogenlolysis, fat breakdown
Paracrine signaling is characterized by ligands that are
secreted by neighboring cells
How does the function of an intracellular receptor differ from that of a membrane receptor?
The intracellular receptor binds DNA.
The action of steroid hormones is often longer-lived than that of peptide hormones. This is because they
they turn on gene expression to produce proteins that persist in the cell.
You experience a longer period than normal between meals. Your body’s response to this will be to produce
glucagon to raise your blood sugar.
Mild vitamin D deficiency can lead to osteoporosis, or reduced bone mineral density. This is thought to be due to an association with increased levels of
PTH, which leads to an increase in serum Ca2+ and bone loss.
Suppose that two different organs, such as the liver and heart, are sensitive to a particular hormone (such as epinephrine). The cells in both organs have identical receptors for the hormone, and hormone-receptor binding produces the same intracellular second messenger in both organs. However, the hormone produces different effects in the two organs. Explain how this can happen.
When a second messenger is produced it tends to activate an enzyme cascade within the cell that brings about a response. Different cells will have unique collections of enzymes that will respond to the presence of the second messenger, so as a result, the final response of the pathway in one cell could be different than another. For example, one cell could produce a physical change in the structure of the cell, while another could undergo a chemical change.
Hormone: ADH
Hormone: ADH
Endocrine Organ: posterior pituitary
Target Organ: collecting duct cells
Function: concentrate urine, cause collecting duct to reabsorb water into the blood
When you consume alcohol…
- block sensitivity of ADH and ADH receptors which will cause less aquoaporins to open up in collecting duct = less water reabsorbed = more concentrated urine = dehydration
The Kidney (an effector organ)
- water balance/BP, remove toxins, nitrogen waste removal
- we combine ammonia with CO2 to make urea, energy cost from synthesizing using ATP but less harmful because less water concentration used
- fish have enough water to excrete ammonia
- gets blood supply from renal artery and vein
- urine formed in kidney, waste filtered from blood plasma
Outer Layer of Kidney
- renal cortex, filtering body fluids and recover useful solutes
Middle Layer Kidney
- medulla, responsible for water recovery and concentrating urine
Inner Layer Kidney
pelvis, collects urine and fullens to bladder
Nephron
- funcitonal unit of kidney, interacts with blood to create a filtrate to recover materials and adjust conctent of filtrate htorugh osmotic potential and passive transport. uses active as well
- Cortex: bowman’s capsule, proximal tubule, distal tubule
- Medulla: descending and ascending loops of henley, collecting duct
Bowmans Capsule
- filtration uses BP and capillaries to extract blood liquid and leave proteins and solids behind
- blood enters capiallaries in glomerulus that surrounds tubules that flow around loop of henley counter current
Proximal Tubule
- active transport where energy congtaining molecules/sugars are recovered such as glucose, amino acids
- water/osmosis filtered out
Distal Tubule
- is sensitive to hormones and changes the composition of filtrate, more water passivley moved in
- maintain blood pH and may gain H or carbonic acid
Loops of Henley
- set up Na+ salt gradient to remove water, puts less salt in higher portions of medulla and vice versa
- when filtrate (now urine) is adjusted and reaches collecting duct the salt gradient draws out water by osmosis
Collecting Duct
- aquaporins protein channels controlled by ADH
