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107 Cards in this Set
- Front
- Back
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Define physiological processes
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Processes based on cellular function
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Define cellular functions
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Functions that obey the laws of physics and chemistry
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Define the Law of Conservation of Energy
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Energy can be converted from one form to another the the total amount of energy is constant
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Define Entropy
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The universe is becoming more chaotic
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Define Energy
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The ability to do work
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Define Energetics
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Energy transfer between systems
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Define potential energy
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Trapped energy
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Define Kinetic energy
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The energy of movement
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What are the 5 energy categories
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Radiant, Mechanical, Electrical, Thermal & Chemical
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What are two main roles of the cell membrane
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1) Isolate cells from the environment
2) Organize intracellular pathways into subcellular compartments |
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What lipids can be found in the cell membrane?
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1) Phospholipids
2) Sphingolipids 3) Glycolipids 4) Cholesterol |
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What phosphoglycerides is the lipid bilayer made of?
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1) Phosphatidylcholine
2) Phosphatidylethanolamine 3) Phosphatidylserine |
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What role do Sphingolipids play in the lipid bilayer?
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Sphingolipids alter electrical properties of the lipid bilayer
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What role do Glycolipids play in the lipid bilayer?
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Glycolipids function in cell communication
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What role does cholesterol play in the lipid bilayer?
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Makes the membrane more fluid but less permeable by interacting with the FA chains in the lipid bilayer
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How is the cell membrane heterogenous?
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1) The lipid bilayer is composed of PE and PS phosphoglycerides in the inner leaflet and PC phosphoglycerides in the outer leaflet.
2) Glycolipids are only found in the outer leaflet 3) Lipid rafts are found throughout the membrane |
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What is a lipid raft?
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A area of the lipid bilayer composed of phosphoglycerides with longer fatty acid chains, causing a thicker region of the membrane to occur.
This raft is enriched with glycolipids, cholesterol and proteins with longer transmembrane regions |
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Describe 3 ways homeoviscous adaptation alters membrane fluidity
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1) FA chain length: shorter chains increase fluidity
2) Saturation: Saturation increases fluidity 3) Cholesterol: Makes membrane more fluid if the environment would otherwise cause the membrane to be solid/gel-like |
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Define Homeoviscous adaptation
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Cell keeps membrane fluidity constant by altering the lipid profile
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What are the two main types of membrane proteins?
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Integral and Peripheral
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What do all transmembrane proteins have?
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Hydrophobic regions
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Three types of active transport pumps
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1) P-type
2) F-type 3) V-type |
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What do P-type pumps do?
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Pump specific ions
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What do F-type and V-type pumps do?
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Pump H+
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Define equilibrium potential
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Equilibrium Potential is the membrane potential at which the ion is at electrochemical equilibrium
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What is membrane potential most dependent on?
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Sodium, potassium and chlorine concentrations
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Define depolarization
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Cell becomes more positive on the inside
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Define hyperpolarization
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Cell becomes more positive on the inside
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What are the two types of cell signaling?
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Direct and indirect
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Describe direct cell signaling
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Signaling cell and target cell are connected by gap junctions
Signal is passed directly from one cell to another Prevalent in invertebrates |
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Describe indirect cell signaling
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Signaling cell releases a chemical messenger which travels through extracellular fluid to a receptor on the target cell
Activates a signal transduction pathway, which stimulates a response |
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Define paracrine signaling
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Indirect cell signaling over a short distance to a nearby cell
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Define autocrine signaling
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Indirect cell signaling that diffuses back into the signaling cell (self signaling)
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Define endocrine system signaling
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Chemical messenger is transported by the circulatory system to target cell
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Define nervous system signaling
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Electrical signal travels along a neuron and a chemical messenger is released
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What are 6 classes of chemical messengers?
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Peptides, steroids, amines, lipids, purines and gases
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What property of a chemical messenger affects signaling mechanisms?
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Structure
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How do hydrophillic and hydrophobic messengers differ in storage?
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Hydrophillic: Intracellular vesicles
Hydrophobic: Synthesized on demand |
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How do hydrophillic and hydrophobic messengers differ in secretion?
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Hydrophillic: Exocytosis
Hydrophobic: Diffusion |
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How do hydrophillic and hydrophobic messengers differ in transport?
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Hydrophillic: Dissolved in extracellular fluid
Hydrophobic: Dissolved in extracellular fluid (short term) or bound to carrier proteins (long term) |
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How do hydrophillic and hydrophobic messengers differ in which receptor they bind to?
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Hydrophillic: Transmembrane proteins
Hydrophobic: Intracellular or transmembrane proteins |
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How do hydrophillic and hydrophobic messengers differ in terms of the speed of response?
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Hydrophillic: Rapid
Hydrophobic: Slower or rapid |
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Describe characteristics of Prohormones
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- 2 to 200 AA long
- Hydrophillic - Synthesized on RER - Stored in vesicles - Secreted by exocytosis - Binds to transmembrane regions - Rapid effects |
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Describe characteristics of steroid hormones
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- Derived from cholesterol
- Synthesized in SER or mitochondria - Hydrophobic - Transported by carrier proteins - Bind to transmembrane receptors or intracellular receptors - Slow effect |
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Explain M + C ⇄ M-C
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- Most messengers bind to a carrier but some remain as free messengers in the blood/extracellular fluid
- When FM diffuse into a target cell, the [M] decreases, shifting the equilibrum to the left - messengers dissociate from carriers and diffuse into the target cell |
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Describe characteristics of Amine Hormones
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- Have an amine group (-NH2)
- Most are hydrophillic - Have diverse effects |
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Describe Eicosonoids
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Messenger involved with inflammation and pain
-Hydrophobic - Act as paracrines |
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What are the three classes of steroid hormones?
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1) Mineralocorticoids
2) Glucocorticoids 3) Reproductive Hormones |
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What hormonal role do Mineralocorticoids have?
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Electrolyte balance
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What hormonal role do Glucocorticoids have?
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Stress
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What hormonal role do reproductive hormones have?
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Regulation of sex-specific characteristics
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Define Agonist
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A ligand what activates receptors
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Define Antagonist
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Ligand that blocks receptors
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Define down regulation
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The target cell decreases the number of receptors
- causes a decrease in the response |
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Define up regulation
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Target cell increases the number of receptors
- Causes a increase in response |
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What are 6 ways a ligand can be inactivated?
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1) Removed by distant tissues
2) Taken up by adjacent cells 3) Degraded by enzyme 4) Ligand-receptor complex removed by endocytosis 4) Receptor inactivation 6) Inactivation of signal transduction pathway |
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What are the 4 components of a signal transduction pathway?
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1) Receiver
2) Transducer 3) Amplifier 4) Responder |
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Describe Intracellular Receptors
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Ligand diffuses across membrane and binds to a receptor in the cytoplasm or nucleus
The LR complex binds and regulates specific DNA sequences & can affect multiple pathways |
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Describe ligand gated ion channels
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Ligand binds to a transmembrane receptor which induces a conformational change. This opens an ion channel that allows ions to diffuse down their electrochemical gradient = change in Vm
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Describe Receptor enzymes
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Ligand binds to receptor which starts a phosphorylation cascade that phosphorylates specific proteins
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Describe the mechanism behind Guanylate Cyclase Receptor Enzymes
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1) Ligand binds and causes a conformational change
2) Activated GC receptor catalyzes the conversion of GTP to cGMP (second messenger) 3) cGMP binds to PKG 4) PKG phophorylates proteins on serine or threonine residues |
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Describe the mechanism behind tyrosine kinase receptor enzymes
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1) Ligand binds and induces the dimerization and autophosphorylation of two TK enzymes
2) Phosphorylated receptors interact with protein kinases 3) Protein kinases signal Ras protein which switches between off and on form 4) Ras stimulates MAPKKK -> MAPKK -> MAPK -> other kinases/transcription factors/proteins |
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Describe the mechanism behind G protein coupled enzymes
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1) Ligand binds to receptor
2) Receptor interacts with G proteins 3) G - subunits dissociate 4) Alpha subunit releases GDP and binds GTP 5) subunits interact with amplifier enzyme to relase second messenger |
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Define/describe CRAC
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Calcium release activated channel
- allows Ca to get into cell - stimulated by emptying of ER and works to replenish level of Ca in ER |
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Define/Describe Na+/Ca+ exchanger
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Membrane protein that moves 3 Na+ into the cell (down its gradient) while moving a Ca+ out of the cell
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Define/Describe PMCA
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Plasma Membrane Calcium ATPase
- Hydrolyzes ATP to pump Ca out of the cell |
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Define/Describe ROCC
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Receptor Operated Calcium Channel
- Requires ligand stimulation to move Ca into the cell |
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Describe/Define VOCC
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Voltage Operated Calcium Channel
-Opens or closes in response to change in Vm |
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Describe the mechanism behind IP3 signalling
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1) Ligand binds to a G protein coupled receptor causing a conformational change
2) Alpha subunit releases GDP and binds GTP 3) Activated alpha unit activates phospholipase C which cleaves PIP3 into IP3 and DAG 4) IP3 can bind to Ca2+ channels in ER to release Ca into the cytoplasm 5) Ca can stimulate PKC which interacts with DAG to produce a phosphorylation cascade |
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Describe the mechanism behind cAMP signalling
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1) Ligand binds to a G(s) protein coupled receptor which causes a conformational change
2) Alpha(s) subunit releases GDP and binds GTP and activates adenylate cyclase 3) Activated AC coverts ATP to cAMP 4) cAMP binds to the reg subunit of PKA which dissociates from catalytic subunit (activates it) 5) PKA phosphorylates proteins 6) if the inhibitory G protein is activated, AC is inhibited |
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What are the components of biological control systems?
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A sensor, integrating center and effector
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Define set point
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The value of the variable that the body is trying to maintain
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What is a positive feedback loop?
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The output of an effector amplifies a variable away from set point
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What is a negative feedback loop?
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The output of an effector bring a variable back to the set point
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What are the two sections of the pituitary?
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Anterior pituitary and posterior pituitary
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Describe characteristics of the posterior pituitary
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-Extension of the hypothalamus
-Neurons originating in the hypothalamus terminates in the posterior pituitary - Neurohormones oxytocin and vasopressin travel in vesicle down axons - First order endocrine pathway |
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Describe characteristics of the Anterior Pituitary
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- Hypothalamus secretes hormones which go through the hypothalamus-pituitary portal into the anterior pituitary which stimulates the release of tropic hormones
-Tropic hormones cause other hormones to be release in the target cell -Third order endocrine pathway |
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Describe how blood glucose is regulated in the body
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Insulin lowers blood glucose and glucagon raises blood glucose
-both are secreted by alpha and beta cells in the pancreas |
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Define antagonistic paitring
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Hormones that have the opposite effects
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Define Additivity
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Hormones cause the same response in a target cell via different signalling pathways
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Define Synergism
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Hormones enhance the effect of other hormones
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Describe how glucose levels in arthropods are controlled
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1) Low blood glucose causes K+ channels to close in sinus gland
2) Sinus depolarizes and releases CHH 3) CHH binds to target 4) Target releases glucose |
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What is the Golgi theory of the the brain/nervous system?
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The brain is a continuous network
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What is the Cajal theory of the the brain/nervous system?
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Neurons communicate by contact
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What are the 4 neural zones?
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1) Signal Reception (dendrites/body)
2) Signal Integration (Axon hillock) 3) Signal Conduction (Axon) 4) Signal Transmission (Axon terminals) |
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What are the 3 functions of neurons
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1) Receive and integrate incoming signals
2) Conduct signals along the neuron 3) Transmit the signal to other cells |
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What are two ways neurons are different from one another?
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1) Ability to receive incoming signals
2) Mechanism of signal conduction and synaptic transmission |
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What are the three functional classes of neurons?
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1) Afferent (Sensory): AP to CNS
2) Efferent (Motor): AP from CNS to organ/muscle 3) Interneuron: AP between neurons in CNS |
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What are 5 types of Glial cells?
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1) Schwann Cell
2) Oligodendrocyte 3) Astrocyte 4) Microglia 5) Ependymal Cell |
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What is a schwann cell?
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A glial cell that forms myelin on motor/sensory neurons of the PNS
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What is a oligodendrocyte
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A glial cell that forms myelin on neurons in CNS
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What is an astrocyte?
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A glial cell that transports nutrients and removes debris in CNS
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What is a microglia
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A glial cell that removes debris and dead cells from CNS
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What is an ependymal cell?
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A glial cell that lines fluid filled cavities of the CNS
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Define deplorization
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Membrane potential becomes less negative (more positive)
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Define repolarization
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Membrane potential returns to resting potential
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Define hyperpolarization
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Membrane potential becomes more negative than the resting potential
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What happens to membrane potential as permeability to a given ion increases
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Vm approaches the equilibrium potential of that ion
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What is the difference between a graded potential and an action potential?
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A graded potential varies in magnitude, travels short distances and decreases in magnitute over distance
An action potential does not vary in magnitude, travels long distances, and uses voltage gated ion channels |
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What is spatial summation?
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Graded potential from different sites influence net charge in membrane
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Define Temporal summation
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Graded potentials occuring at slightly different times influence net charge in cell
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What are the three stages of an AP
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1) Depolarization
2) Repolarization 3) Hyperpolarization |
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Define absolute refractory period
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Cell incapable of generating a new AP in this time
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Define relative refractory period
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Difficult to generate a new AP in this time
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Describe how an AP occurs
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1) Resting State: (-70mV) K+ permeability is dominant
2) Depolarization (-55 -> 30 mV): Na+ channels open and Vm appraches E(Na) 3) Repolarization (-10mV): Na+ channels inactivate, voltage gated K+ channels open 4) Post- Hyperpolarization (-80mV): K+ channels close slowly, Vm approaches E(K+) |
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How do voltage gated Ca channels affect AP
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- Open at the same time as or instead of Na channels
- Influx is slower but more sustained than Na influx - creates longer refractory period, therefore slower AP frequency |
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What are two ways to increase the speed of a AP
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1) Myelination
2) Increase diameter |
