BIO-206- Test 1

How does a reflex control pathway work?

*check slides stimulus-->receptor-->afferent-->Int center(feedback loop)--> efferent--->effector--->response

axon

*conducts ACTION POTENTIAL away from cell body arises from AXON HILLOCK(beginning of axon) -occasional branches along length(collaterals). 1000s branches at its end, each with an AXON TERMINAL(lots of vesicles with neurohormones and mitochondria. have mitochondria because needs more ATP for endocytosis and exocytosis)

How is an action potential generated and conducted? You should be able to describe what is happening at the cellular/molecular level during an action potential, and you should know the names of the phases and what is happening during those phases.

*draw this out for practice graded potential triggers an action potential 3 phases: Rise, falling, hyper polarization 1. starts at resting membrane potential(-70mV). 2. then depolarizing stimulus occurs 3. membrane starts a sudden rise because voltage gated sodium channels open and cause depolarization of Na. 4. rapid Na+ entry into cells occurs 5. at the peak of +30mV, Na+channels being to close and K+ channels begin to open. 6. K+ then moves out of the cell into the ECF, causing repolarization. 7. K+ channels remain open and leaks K+ out, causing hyper polarization. 8. K+ voltage channels begin to close, allowing not as many K+ ions to leak out. 9. Cells then return to resting ion permeability and resting membrane potential. Na+ gates reset.

dendrites

*processes that receive impulses - convey GRADED POTENTIALS(travels through cell body) to the cell body

Contact dependent signals

- binding between surface molecules and receptor proteins

cell body

- contains nucleus and organnells *synthesizes and makes nuerocrine molecules -Cluseter of cell bodies in CNS=nuclei. PNS= ganglia

What is the basic chemical structure of a phospholipid? How might phospholipids arrange in aqueous solutions? What other lipids are present in cell membranes?

-polar(hydrophilic) head -non-polar (hydrophobic) tail -in aqueous solution they can form BILAYERS, MICELLES and LIPOSOMES.

What characteristics define a given chemical signal as a hormone?

-secreted by a cell or group of cells (endocrine glands, isolated ENDOCRINE glands, neurons and immune system cells) -secreted into blood(though ECTOHORMONES are released into external environment) - transported to a distant target (paracrine and autocrine regulators don't qualify, though thesis complicated -exert their effect at low concentrations e.g. hormones can be used for growth and development, metabolism, regulation of body temp...etc

How might ion channels be opened/closed during a signaling pathway? How might changes in ion permeability affect the cell?

-some ion channels are directly linked to G proteins -some ion channels respond to second messengers activated by G proteins -ion channels can also be opened/closed by binding to extracellular signaling molecules(rapid way of cellular response) -changes in permeability affect the cells membrane potential, which can affect voltage-sensitive proteins(ion channels open/close, flow in and out, helps other ion channels then open)

What is occurring at the cellular and subcellular level at a chemical synapse?

1- action potential reaches terminal and depolarizes 2- opens up voltage gates 2+ channels and Ca2+ enters 3- Ca triggers exocytosis of synaptic vesicles contents 4- neurotransmitters diffuse across a synaptic cleft and bind with receptors on a postsynaptic cell. 5- neurotransmitter binding initiates response in postsynaptic cell.

How are neurocrines removed from the synaptic cleft?

1- most common way is being removed back towards the axon terminal for reuse or transported to glial cells. 2- some just diffuse out of the cell being separated from receptors 3- some can be terminated by enzymes in the synaptic cleft example of neurocrine termination: recycling of acetylcholine. check slides if you need steps?

What are the main different types of neurocrine molecules? What are the differences in effects between nicotinic and muscarinic cholinergic receptors? α-adrenergic and β-adrenergic receptors?

1. Acetylcholine 2. Amines *Norepinephrine 3. Amino acids *GABA

What are the main functions of cell membranes, and why are they important?

1. Physical Isolation- BENEFIT, is you can regulate what exists and enters. Allows cells to have different environment inside than out. 2. regulation of exchange with environment- nutrients/wastes/ions..etc. 3. communication between cells and its environment- cell membrane communicated with environment 4. structural support- supports/binds to cytoskeleton.

What are some different ways that one could classify various hormones?

1. SOURCE- look how many organs actually produce hormones, not just classic glands. 2. CONTROL OF RELEASE- example, controlled by the brain 3. RECEPTOR TYPE- if they bind to G protein coupled receptors, tyrosine kinase linked receptors, intracellular and so on. 4.CHEMICAL STRUCTURE- what we will do here, what hormones are made of. (Peptide, amino, steroid...)

What are the main steps in a signal pathway?

1. Sending of a signal *synthesis and release of a signaling molecules *signal must be transported to target cells 2. Signal reception *typically through binding of signaling molecules(LIGANDS) to RECEPTOR PROTEINS of TARGET CELLS 3. Signal Transduction and amplification *converts intercellular(out) to intracellular signal(in) *involves chain of molecules to relay information and amplify the signal(SECOND MESSENGERS) 4. Response *molecules trigger change in cellular process.

In what ways might a hormone act on its target?

1. they control the rates of enzymatic reactions 2. they control the transport of ions across cell membranes(can change polarity of the cells) 3. they can control gene expression and the synthesis of proteins 4. they can control contraction or relaxation of smooth muscle. *hormonal communications are usually slower than those of the nervous system(rapid)

How is active transport different from passive transport?

ACTIVE TRANSPORT- involves moving a substance against its concentration gradient. low---> high by using an input of ENERGY. *different than facilitated diffusion because it uses an energy source to push molecules against it's concentration gradient. It also moves against its concentration gradient from low--->high so it the direction is different.

Amines? α-adrenergic and β-adrenergic receptors?

AMINES- are derived from single amino acids *includes serotonin, histamine, dopamine, epinephrin and NOREPINEPHRINE- activates ADRENERGIC(means neuron that secrets norepinephrine) RECEPTORS Adrenergic receptors are G-protein coupled receptors: a-adreneergic: contract smooth muscle in blood vessels b-adrengergic- relax smooth muscle in digestive tract, increases heart rate and force of contraction.

How do the phenomena of spatial and temporal summation contribute to the generation or inhibition of action potentials?

Action potentials are not generated unless the threshold depolarization is reached at the trigger zone. Depolarized cells make it easier for a graded potential to be above the threshold at the trigger zone because its starting point is more positive, further above threshold in order to maintain it. pushes the membrane potential closer to threshold for voltage gated channels(EXCITATORY POSTSYNAPTIC POTENTIALS) Hyper-polarized cells make it harder because its more negative and pushes the membrane potential away from the threshold for voltage gated channels (INHIBITORY POSTSYNAPTIC POTENTIALS)

Why don't action potentials overlap? Why can't an action potential be conducted backwards? What is the difference between the absolute and relative refractory periods?

Action potentials don't overlap because of refractory periods. ABSOLUTE REFRACTORY PERIOD- the brief time during which a 2nd action potential cannot be triggered, no matter how strong the stimulus. Na+ channels are reseting to normal resting period, action potential can't start until the channels reset. *action potentials moving from trigger zone to axon terminal cannot overlap and cannot travel backward. Ensures a one way travel of an action potential from cell body to axon terminal by preventing the action potential from traveling backward. RELATIVE REFRACTORY PERIOD- the time when a higher than normal graded potential is required to trigger an action potential. during depolarization, Na+ channels are still closing and K+ channels are open. Can trigger action potential but needs a stronger stimulus to reopen the Na+ channels. This action potential will have a lower than normal amplitude.

What is the difference between tonic(agonist ?) and antagonistic control?

Agonist- binds and activates a response just like the primary ligand. Antagonist- binds and blocks the receptor activity. ex- anahistamines

What are the structural differences between AMINE, peptide, and steroid hormones?

Amine Hormones- these are derivatives of single amino acids *created from either tyrosine or tryptophan *EXAMPLES: dopamine, epinephrine, thyroxine, and melatonin

How are sensory, motor, and mixed nerves different from one another?

Axon s are bundled into nerves(bundle of cells). Sensory- to CNS, Motor nerves- out to response, Mixed nerves- does both, can take info out and in of both PNS and CNS.

How does a signaling cascade operate? What types of enzymes are often involved, and how do they work? How does a signaling cascade often result in signal amplification?

CASCADES- utilizes sequential enzyme activation; often utilizes KINASES: are enzymes that carry phosphate groups and bind it to proteins. intracellular signal pathways are cascades. blood clotting is an example of extracellular cascades. SIGNAL AMPLIFICATION- turns one signaling molecule into many SECOND MESSENGERS- one signal molecule(or ligand) turn into many secondary messengers.

What role is played by carbohydrates associated with the cell membrane?

Carbohydrates create GLYCOPROTEINS and GLYCOLIPIDS which: *form protective layer on outside of cell (glycocalayx) *plays key role in body's immune response (ABC blood groups)

How are hormones produced and released via the posterior pituitary? What roles do vasopressin/ADH and oxytocin play?

Cell bodies in hypothalamus produce VASOPRESSIN(acts on kidneys to regulate water balance in the body) and OXYTOCIN(controls the ejection of milk during breast feeding and contractions of the uterus during labor and delivery) hormones are packaged in vesicles of cell boy of the neuron and sent down an axon into the posterior pituitary, where they are stored until a release signal happens. exocytosis of hormones occurs then when calcium enters the cell. Then hormones are released into a blood vessel.

How are steroid hormones synthesized, stored, transported, and received?

Cells that secrete steroid hormones usually have large amounts of ENDOPLASMIC RETICULUM. Steroid secreting hormones can't be stored in secretory vesicles. they are LIPOPHILIC- diffuse easily out of parent cells and into target cells. Cant be stored in vesicles of parent cells steroid hormones much be synthesized ON DEMAND from precursor converting to active hormone in the cytoplasm(basically synthesize as its needed) *intracellular(hormone) rises-->diffusion out of the cell

What are the different divisions and subdivisions of the nervous system? What is the general flow of information in the nervous system?

Central Nervous System- insists of the brain and spinal cord. Peripheral Nervous System- consists of the Sensory(afferent) division and the motor (efferent) division. These send signals to and from the CNS. Motor divison divides into the somatic(skeletal) and autonomic division(visceral, organs and smooth muscle) Autonomic divison divides into the: sympathetic, parasympathetic and Enteric nervous system

What are the different types of channel proteins? What conditions might cause a gated channel to open or close?

Channel proteins: -channels make openings and make pores, unlike carrier proteins. -water channels are made up of a protein called AQUAPORIN -hundred types of ion channels -OPEN (LEAKY) CHANNELS: the gates are always open. Allow ions to move back and forth across a membrane. -GATED CHANNELS(3 kinds): there are chemical(ions) which are controlled by intracellular messenger molecules that bind to channel proteins volted(voltage) open and close when electrical state of the cell changes mechanically gated(physical force)- response to physical forces, such as increased temp or pressure that puts tension on the membrane and pops the channel gate open.

What factors can affect the speed of action potential conduction?

Check slides for steps: action potential conduction is how the action potential travels down toward axon terminals. Example of positive feedback because depolarization opens Na+ channels, and Na+ enters and it just keeps depolarizing and opening Na+ channels to conduct the action potential to the axon terminal. Conduction speed is influenced by: 1. diameter of the axon- charges encounter resistance from membranes, thus larger diameter--> faster conduction 2. resistance of the membrane to ion leakage out of the cell- more leak-resistant membrane--->faster confuction 3. Degree of mylenation- mylenated axons helps to minimize current leak--> faster conduction

What are the body's main fluid compartments?

Component are ICF and ECF ECF: 1/3 *can be interstitial fluid(little bit of fluid surrounding not fully bound cells) *blood plasma, cerebrospinal fluid and synovial fluid. ICF: 2/3- fluids inside cell *these components are separated by membranes. CELL MEMBRANES are barriers for ICF and ECF.

What are the different parts of a control system, and what do they do?

Components: input signal(STIMULUS) integrating system(defines the SET POINT..optimal pt of body like ph, temp)- reads the stimulus Output signal(creates RESPONSE)

How specific is the ligand-receptor relationship? What are the different outcomes when a receptor binds to a ligand?

Different ligands with a similar structure may be able to bind to the same receptor *example- "fight or flight response" norepinephrine and epinephrine bind to a class of receptors called adrenergic receptors, though some subtypes have a higher affinity for one or the other. One ligand may have multiple receptors as well. Different ISOFORMS of a receptor may initiate different transduction pathway *ex. epinephrin binds to B2 isoform because it has a high affinity for it. adrenergic receptors have an alpha and beta isoforms for binding sites, these can change the results of the systems like constricting or dilating blood vessels based on the isoform receptor.

What are neuronal divergence and convergence?

Divergence- when a single presynaptic neuron synapses with multiple target neurons Convergence- when a group of presynaptic neurons provide input to a smaller number of neurons. converge into one neuron.

How do electrical synapses work? Where might you find them?

ELECTRICAL SIGNALS- these utilize GAP JUNCTIONS to move from cell to cell- which are connected and have channels for signals to pass through cells. These are found in neurons of the CNS, glial cells, cardiac and smooth muscle. Advantage of electrical signals is that its rapid and has bidirectional signals from cell to cell synchronized activity with network of cells.

How does the hypothalamic-pituitary feedback system work? What is the difference between long-loop and short-loop negative feedback?

Each released hormone acts to suppress hormone secretion by integrating centers earlier in the pathway. LONG LOOP- when the last hormone in a pathway feeds back to suppress secretion of other hormones SHORT LOOP- pituitary hormones feed back to suppress hypothalamic tropic hormones. Hormones produced by the anterior pituitary shuts off hormones. *DIFFERENT from other feedback loops because they shutting off production of hormones, not just turning off the stimulus.

How can these be diagnosed?

Endocrine pathologies may also be triggered by changes in the responsiveness of target tissues. examples: hyperinsulinema and down regulation of insulin mutations in the protein sequence of androgen receptors in androgen insensitive syndrome genetic alterations in signal transduction pathway proteins(G proteins).

How does facilitated diffusion work? At what stage is ATP involved?

FACILITATED DIFFUSION- another form of passive transport, doesn't need energy. *transported molecules move down their concentration gradient. *uses ATP to make gp6 storage for glucose *when equilibrium is reached the glucose concentrations inside and outside the cells are equal. Net movement stops when equilibrium is met. Glucose gets phosphorylated so that the concentration of substrate in the cell stays low avoiding equilibrium.

What determines the speed of a postsynaptic response? What's the difference between a neurotransmitter and a neuromodulator?

Fastest response when ion channels are open or closed. Neurotransmitters create rapid, short acting fast synaptic potentials. Slowest response happens through G-protein coupled receptors. Neuromodulators create slow synaptic potentials and long term effects. Slow because it activates second messenger pathway, can modify existing proteins or regulated synthesis of new proteins to coordinate intracellular response.

How does a G protein signaling pathway operate? What types of proteins, enzymes, and other molecules are involved?

G-PROTEIN COUPELED RECEPTORS(GPCR)- crosses lipid bilayer 7x. receptors cytoplasmic tail is associated with G PROTEIN: *made up of 3 subunits * inactive when bound to GUANOSINE DIPOSPHATE(GDP) *active when bound to GUANOSINE TRIPOSPHATE(GTP) *active G proteins may open an ion channel or alter enzyme activity

What are glial cells? What are the functions of oligodendrocytes and Schwann cells? How do they differ from one another?

GLIAL CELLS- or neuroglia, which provide physical support and communicate with neurons. More abundant than neurons. Glial cells in the CNS: ependymal cells, astrocytes, microglia and OLIGODENDROCYTES oligodendrocytes- form myelin sheets around axons in the CNS. Glial cells in the PNS: SCHWANN cells and satellite cells. SCHWANN cells- form the myelin sheath in the PNS. Difference between this and oligodendrocytes is that schwann cells only wrap one cell around axons. Node of Ranvier- segments in between Schwann cells that are unmylenated.

How does a G protein signaling pathway operate? What types of proteins, enzymes, and other molecules are involved?

GPCR-cAMP pathway was first signal transduction pathway. transduction system for many protein hormones. it uses adenylyl cyclase as the amplifier molecule that converts ATP to second messenger molecule cyclic AMP. cAMP then activates protein kinase A, which then phosphorylates other intracellular steins for part of signal cascade.

Spatial and Temporal summation

Graded potential integrate- EPSPs and IPSPs are added together. Temporal Summation- 2 events occurring close together in time at the same location *if two sub thresholds graded potentials arrive at trigger zone within a short period of time, they may sum and initiate an action potential Spatial summation- 2 simultaneous events occurring near to each other in space. *summation- several sub threshold signals results in an action potential *synaptic inhibition- one IPSP sums with two EPSP's to prevent an action potential in the postsynaptic cell.

How is a graded potential generated, and what are some of its properties?

Graded potentials are variable strength signals that travel over short distances and lose strength as they travel through the cell *can be depolarizations or hyperpolarizations *typically occur in dendrites, cell bodies and sensory receptors *amplitude is directly proportional to the triggers event, but falls with increasing distance from stimulus. **if strong enough, it may reach the TRIGGER ZONE(axon hillock)- if strong enough it can trigger an action potential to pass on signal. further ions go, less strength.

What are the causes and effects of hypersecretion and hyposecretion?

HYPERSECRETION- to much hormone is secreted causes: benign tumors of endocrine glands Malignant tumors of endocrine glands occasionally non-endocrine tumors treatment: with an exogenous hormone can have similar effects. glands may atrophy(die), making them unable to regain normal function after treatment. HYPOSECRETION- to little hormone is secreted most common cause: atrophy of cell can cause trophic hormone levels to rise drastically.

What ions are more concentrated in ECF and ICF respectively?

ICF- high amounts of K+ and proteins ECF- interstitial fluid: high NA and Cl plasma: High Na, Cl and proteins

What properties of a molecule dictate how quickly it diffuses across a cell membrane? What properties of the cell membrane itself affect the rate of diffusion?

If these increase: Distance of diffusion- decreases speed Concentration gradient- increases Temperature- increases Size of a molecule- decrease Properties: If surface area increases- it increases the speed of diffusion If more permeability to a molecule- increase in diffusion If membrane is thinner- rate of diffusion increases

UP regulation

Increase in the number of receptors *often in response to low amount of ligands *receptor addiction occurs via exocytosis- more receptors will be brought to the surface. ex. neuron is damaged and can't release normal amount of neurotransmitters. the target cells will up regulate surface receptors. This also is used during development for growth factors.

What are the primary ions that affect resting membrane potential? Where are each of these ions more concentrated?

K+ - ICF, Na+- ECF, Cl- ECF, CA2+- ECF. -Electrochemical gradients for K+ Na+ Cl- and Ca+(though resting cells are not permeable to Ca+) -Cell membrane is more permeable to K+ than Na+ and Cl--->RMP closer to Ek -leak of Na+ into the cell makes the RMP less negative than Ek+ -changes in the K+ concentration gradient or ion permeabilities alter the membrane potential.

What determines whether a ligand binds to a target cell receptor inside the cell or on the cell surface? How is the response time different between these two methods?

LIPOPHILIC LIGANDS- which diffuse through the cell membrane and bind to receptors inside target cells. These are slow responses related to changes in gene activity. ex. Steroids or hormones LIPOPHOBIC LIGANDS- remains in the ECF and binds to the receptors on the surface on the target cell, can't go through the cell membrane. This is a rapid cellular responses. ex. peptide and amine signals

How do the different forms of local communication work?

LOCAL COMMUNICATION- occurs over very short distances...types of them:

What properties of a molecule or ion dictate how it gets across a cell membrane?

Molecules such as oxygen, C02,, and lipids move easily across cell membranes. Ions, most polar molecules and very large molecules(like proteins) have more difficulty crossing membranes. TWO PROPERTIES: the size of the molecule and lipid solubility. Small molecules and lipid soluble pass easier than big and non polar molecules. and also lipid composition of the membrane.

What is a neurocrine molecule? How do neurotransmitters, neuromodulators, and neurohormones differ from one another?

NEUROCRINE molecule- electrical signal is converted into a chemical signal. NEUROTRANSMITTERS- travel short distances and have rapid effects. NEUROMODULATORS- travel short distances but act slowly. NEURHORMONES(long distance)- are released into the blood and circulate through whole body. difference between this and hormones is that its produced by neural cells. Similar in that they bridge the gap between the nervous system and endocrine system.

How do local anesthetics and other neurotoxins work?

NEUROTOXINS- bind to and block Na+ channels. Then the Na+ channels can't function an thus Na+ can't enter the axon. No depolarization will occur so therefore no action potentials can be generated. similar to anesthetics called procaine, which blocks sensation. Local anesthetics- example like lidocaine, novocaine, Tetrodotoxin(TTX)- this is found in puffer fish

What are the functions of the different parts of a neuron?

Neurons- are highly specialized cells that transmit messages in the form of electrical signals from one part of the body to another.

What is osmosis, osmotic pressure and how does it work?

OSMOSIS- movement of water across a membrane to differences in concentrations of solute *Water movement: dilute solution --->concentrated solution OSMOTIC PRESSURE- exact amount of pressure needed to oppose the H20 movement.

What does it mean to say that extracellular fluid (ECF) and intracellular fluid (ICF) are simultaneously in a state of OSMOTIC EQUILIBRIUM and chemical disequilibrium?

OSMOTIC EQUIL- water is the only molecule that freely moves in and out of the iCF and ECF, so theres equal concentrations *Homeostasis does not equal equilibrium, a continual input of energy helps maintain chemical and electrical disequilibrium, which is important for physiological functions.

How do the different types of ion channels work? OPEN LEAKY CHANNELS

Open leaky channels- nearly always open

How does one calculate a solution's molarity? Osmolarity?

Osmolarity- OsM=osmoles(particles) of solute/liter of solution Molarity- moles of solute/liter of solution

What are the differences between paracellular transport, transcellular transport, and transcytosis?

PARACELLULAR- between the junctions of adjacent cells(between cells). this is more rare because of the tight junction than trans cellular and increased movement through can be a hallmark for disease. TRANSCELLULAR- goes through the cells and crosses two membrane, first and second compartments. Transcellular uses a combination of active and passive transport. TRANSCYTOSIS-molecules that are to large to cross epathelia on membrane transporters use transcytosis. This is a combination of endocytosis, vesicular transport(helps cross membrane) and exocytosis. Makes it possible for large proteins to pass membrane.

What are the differences between phagocytosis, endocytosis, and exocytosis?

PHAGOCYTOSIS- is the actin-mediated process by which a cell engulfs a bacterium or other particle into a large membrane bound vesicle called a phagosome. Requires ATP and imports large molecules and particles. ENDOCYTOSIS- second process by which large molecules or particles move into cells, differs from phagocytosis in 2 ways: membrane surface indents or invaginate rather than pushes out. and vesicles formed are much smaller. EXOCYTOSIS- opposite of endocytosis. the intracellular vesicles move to the cell membrane and fuse with it and release their contents to the ECF. This is used to export large lipophobic molecules such as proteins synthesized in cell and to get ride of wastes left in lysosomes from intracellular digestion.

What is physiology and how does it relate to anatomy?

PHYSIOLOGY- the study of normal functioning of a living organism and it's component parts. *closely tied with anatomy(form and macroscopic) and physiology focuses on the (function microscopic). *Form-->function *integration of function across multiple levels of organization.

What is the difference between primary active transport and secondary active transport?

PRIMARY ACTIVE TRANSPORT- uses ATP as energy source. *ex. Sodium-Potassium pump, primarily ATPases. SECONDARY ACTIVE TRANSPORT- uses the potential energy stored in a concentration gradient. -indirectly driven by ATP -can involve symport(same direction) or anti port(both directions) ex. Sodium-glucose secondary active transporter *Na goes with its concentration gradient. *glucose goes against its concentration gradient **ATP is involved from the concentration gradient by using the potential energy in Na+ to use for moving molecules across a membrane.

What is the difference between a primary endocrine pathology and a secondary endocrine pathology? How can these be diagnosed?

PRIMARY PATHOLOGY- arises in the last endocrine gland in a complex reflex pathway. ex. if tumor in the adrenal cortex begins to produce excessive amount of cortisol, the resulting condition is called primary hypersecretion SECONDARY PATHOLOGY- when a problem lies in the anterior pituitary or the hypothalamus. ex. if pituitary is damaged because of head trauma and ACTH secretion diminishes, the resulting cortisol deficiency is considered to be secondary hypersecretion.

What hormones are released via the anterior pituitary, and what are their functions?

PROLACTIN- controls milk production in the female breast GROWTH HORMONE- affects metabolism of many tissues in addition to stimulating hormone production by the liver. FOLLICLE STIMULATING HORMONE(FSH) and LUTEINIZING HORMONE(LH)- known as gonadotropins, are known for the effects ion the ovaries but also the testes. THYROID STIMULATING HORMONE(TSH)- controls hormone synthesis and secretion in the thyroid gland. ADRENOCORTICOTROPHIC HORMONE(ACTH)- acts on certain cells of the adrenal cortex to control the synthesis and release of steroid hormone cortisol.

What are the different types of membrane proteins, and what are their various functions?

Peripheral proteins- surface of lipid bilayer, can be in it. integral proteins-tightly bound to membrane *transmembrane- crosses membrane * lipid-anchored- covalently bound to lipid tails.

How do the different types of membrane receptors work? Receptor- channel

RECEPTOR-CHANNEL- ligand binds and opens/closes the channel

What is the average resting membrane potential of a neuron? How is this explained with respect to Na+ and K+ ions, leak channels, and the sodium-potassium pump?

RESTING MEMBRANE POTENTIAL- is an electrical gradient that exists between the ICF and the ECF. cells end with more positive ions outside and more negative inside. POTENTIAL OF A NEURON- -70 mV, more leaky channels for K+ leading more K+ ions on outside of surface Na+(offsets potential to (-70) can leak into the cell and K+(causes membrane to be (-90) out but not at the same rate. *sodium-potassium pump uses the active transport of K+ and Na+ to maintain this negative membrane potential by brings 3 Na out and 2 K+ in to keep RMP at -70.

What is saltatory conduction, and how do myelinated axons conduct impulses more rapidly than unmyelinated axons?

SALTATORY CONDUCTION- the apparent jump of the actin potential from node to node. oligodendrocytes and schwa cells create myelination for resistance of leakage. unmylenated conduction- moves a lot slower, needs to be reinforced with every ion channel. mylenated conduction- moves a lot faster, reinforced at every node of Ranvier. This is the jumping of action potential from node to node.

What are the different functional categories for classifying a neuron?

SENSORY (AFFERENT) NEURONS- carry information from receptors to CNS. Can be pseudo unipolar or bipolar INTERNEURONS(between two neurons in CNS)- lie entirely within the CNS. Complex branching processes to communicate with many neurons. 99% in body and are multipolar. MOTOR(EFFERENT) NEURONS- creates respinse in body, includes somatic motor and autonomic neurons. Large axon terminals and varicosities for storing neurocrines. Most are multipolar.

What are the different ways in which hormones can interact with one another?

SYNERGISM- occurs ehn 2+ hormones together produce an effect greater than simply adding their individual effects. ex. glucose levels. epinephrin and glucagon together are better than them separate. PERMISIVENESS- occurs when one hormone cannot fully exert its affects unless a second hormone is present. ex. reproductive development thyroid hormone alone--> no development FSH and LH alone--> delayed development THYROID HORMONE, FSH and LH---> normal ANTAGONISM- occurs when the effects of one hormone produce the opposite effects on another hormone ex. Insulin(decreases BP) and glucagon(increases BP).

When might a cell down-regulate or up-regulate a certain receptor, and how would these situations affect the target cell's sensitivity to a signal?

Saturation- occurs when protein activity reaches a maximum rate based on the number of active proteins(when all ligands are bound to receptors) *a cell has 50-100,000 surface receptors DOWN REGULATION- decrease in receptor number *causes by a prolonged high of ligands *removal occurs via endocytosis(more receptors will be brought in the membrane) *DESENSITIZATION- binding a chemical modulator to the receptor(often phosphorylation) this can change structure of receptor by binding phosphates to down regulate. ex. drug tolerance

Amino Acids? How does GABA act as an inhibitory neurocrine?

Several amino acids function as neurocrine molecules in the central nervous system - Gamma- aminobutyric acid (GABA) *main inhibitory neurocrine in the brain *causes hyper polarization in postsynaptic cells by opening cl- channels--> Cl- flows into the cell(more action potentials, makes cell more negative) applications of GABA: -Hunigtons disease- more spasms, not enough GABA to control muscles - Tetanus toxin- prolonged contraction of muscles because GABA is blocked.

other lipids?

Sphingolipids *fatty acid tail, but different backbone *head contains phosphorus or sugar residues *larger than phospholipids *associate with lipid anchored proteins to form LIPID RAFTS Cholesterol- hydrophobic mostly *helps membrane maintain fluidity(filling gaps) *makes membrane impermeable to small water-soluble molecules

How are peptide hormones synthesized, stored, transported, and received?

Starts off as a PREPOHORMONE(which contains 1+ copies of the peptide hormone and a SIGNAL SEQUENCE(directs protein into lumen of ER) Then the signal sequence is removed--->making it a PROHORMONE (not quite active yet) Golgi complex then packages pro hormone with PROTEOLYTIC ENZYMES(which clip the pro hormone into active hormones and other fragments) secretory vesicles with an active hormone are stored in the cytoplasm until the cell receives a signal to induce SECRETION

Synapses

Synapses are the regions where an axon terminal meets its target cell *presynaptic cell- delivers signal to synapse *synaptic cleft- narrow space between pre and postsynaptic cells *postsynaptic cell- receives signal at the synapse

How are local controls different than (systemic) reflex controls?

There can be LOCAL CONTROLS(low 02-->vasodilation blood vessels localize low O2 levels near the point) and systemic REFLEX CONTROLS (changes in BP, happens through systems of brain to do changes, not as local)

What does it mean to say that an action potential is an "all-or-none" phenomenon?

There is an all-or-none phenomenon threshold(about -55mV) that must be reached in order to trigger an action potential. They either occur at maximal depolarization when the stimulus reaches threshold or they do not occur at all, when stimulus is below threshold. The strength of graded potential that initiates the action potential has no influence on the amplitude of the action potential.

How are the steroid hormone signals transduced?

They are not soluble in plasma- must be transported by bounding to protein carriers in the blood. *this protects hormones from degradation(which is why they have longer half-life) *half life-long *slower response than peptide hormones must be released to enter cell because proteins limit ability to enter target cells *most not all act on intracellular receptors(cytoplasm and nucleus) Complex acts as a transcription factor

How does the control pathway for secretion of cortisol work?

This is an example of feedback loops. Cortisol is a stress hormones, increases BP and surpasses immune response. 1. hypothalamus secretes CRH(corticotropin-releasing hormone) 2. CRH stimulates the anterior pituitary to release ACTH 3. ACTH travels to the adrenal cortex, stimulating the release of cortisol. 4. cortisol then feeds back to inhibit further secretion of CRH and ACTH by the hypothalamus and anterior pituitary respectively

What is a hormone's half-life? How do the half-lives of peptide and steroid proteins compare to one another? What accounts for this difference? How are hormones eliminated from the body?

a hormones HALF-lIFE is the time it takes for the concentration of the hormone to drop by 50 %. PEPTIDE hormones- short half lives(seconds to minutes) due to their solubility in water(can diffuse from blood vessels to the enzymes that inactive them) STEROID hormones- longer half lives (60-90 minutes) because they are bound to plasma proteins and inaccessible to inactivating enzymes inactive hormone metabolites produced by degradation are eliminated by the liver and kidney.

Autocrine signals

act on the same cell that secreted them. goes into interstitial fluid and binds to the same cell. Can use both paracrine and autocrine signals at the same time.

Paracrine signals

actor neighboring cells(on different cells) then the one that secreted it. ex. a bump after scratching

feedforward control

allows the body to predict that a change is about to occur, allowing the response loops to start in anticipation of the change ex. salivation reflex, cardiovascular system and gastroilliac reflex(anticipating them happening)

Transporters?

are membrane proteins that move molecules across membranes. Include channel and carrier proteins.

What are some of the critical levels of membrane potential (in mV) for an average neuron: resting membrane potential, threshold, depolarization maximum, hyperpolarization maximum?

at resting state: (-70mV) depolarization stage: if graded potential depolarizes to threshold(-55mV) then gated channels open. Membrane potential will depolarization maximum of (+30mV). Hyperpolarization: period where K+ permeability persists longer than needed to restore the resting membrane potential (-90mV).

Biorhythms

can result from orderly changes in the set point of a system ex. CIRCADIAN RYTHM- sets where your body temp will be, daily biological rhythm to when your body temp goes up. For morning people it can be right in the morning.

Carrier proteins?

carrier proteins are tropical slow transporters. They never form an open channel between both sides of the membrane. UNIPORT CARRIERS- carry one molecule(substrates) these are typically slow transporters. COTRANSPORTERS- can carry multiple ions across a membrane.

GPCR-cAMP Pathway

check pg. 175 steps on next slide

How does the sodium-potassium pump work?

check slides

How does the sodium-glucose secondary active transporter work? At what stage is ATP involved?

check slides -Na+goes with its concentration gradient. glucose goes against its concentration gradient. -uses concentration gradient from Na K pump to use it for moving molecules.

What are all of the different components of a cell membrane? What functions do they serve?

components: cholesterol, phospholipids, spingholipids, carbohydrates and proteins. Cholesterol and Phospholipids together form the lipid bilayer- functions as a barrier b/w cytosol and external environment Carbohydrates and Sphingolipids form GLYCOPROTEINS and Carbohydrates and Proteins form GLYCOLIPIDS- both functions or structural stability, cell recognition and immune response. *higher protein= more mitotically active

gap junctions

connexion proteins connect the cytoplasms of adjacent cells(good for electrical to chemical) channels between cells, found in cardiac cells.

GPCR-Phospholipase C Pathway

converts a membrane phospholipid into two lipid-derived second messenger molecules. 1. signal molecule activates receptor and associated g protein 2. g protein activates phospholipase C(PLC), an amplifier enzyme 3. PLC converts membrane phospholipids into diacylycerol(DAG), which remains in membrane, and IP3, which diffuses into the cytoplasm. need more steps?

In what ways might a postsynaptic neuron respond to a stimulus? How is the strength of the stimulus passed on?

e.g. open a Na+ channel-->depolarization--> EPSP e.g. open K+ channel---> hyper polarization--> IPSP(harder for action potential to be triggered) *different signals from different presynaptic neurons are integrated to determine whether or not an action potential is generated in the postsynaptic neuron. (it generates the graded potential to see if its high enough for trigger zone to trigger action potential) *Stronger the stimuli->higher freq of action potentials--> more neurocrine molecules releases

How is negative feedback different from positive feedback? What are some biological examples of each?

feedback loops-->turn of stimulus within bad ranges NEGATIVE FEEDBACK- response opposes/removes the original stimulus; stops response loop. ex. ph gets to high, negative stops stimulus to bring down. Also blood glucose levels, temperature and down regulating receptors.

At what levels of organization does physiology operate?

focuses primarily on organs, organ systems, organisms and population of one species.

voltage gated ion channels

found in all neurons; respond to changes in a cells membrane potential. Most important ion channel. *threshold voltage varies from one channel to another Channels open at diff rates (K+ usually slower than Na+) channel inactivated happens at diff rates

Chemically gates ion channels

found in most neurons; respond to extracellular ligands(neurocrine molecules) or intracellular signaling molecules(second messenger)

Mechanically gates ion channels

found is sensory neurons; open in response to physical forces

liposomes

has an aqueous hollow center

What is the law of mass balance, and how does it relate to homeostasis?

homeostasis requires the body to maintain MASS BALANCE. *means what comes in needs to equal what comes out. input=output. *feeding muscles and getting rid of waste could be how it relates.

Transepithelial transport of Glucose

how active and passive transport can work together to transport glucose.

What is the resting membrane potential of most neurons? What could cause depolarization? What could cause hyperpolarization?

if Na+ enters the cell--> DEPOLARIZATION(more positive inside the cell) if K+ exits the cell or Cl- enters the cell--> HYPERPOLARIZATION( more negative inside the cell) *these aren't changes in ion concentration. can change polarity without changes in concentration.

why is maintaining homeostasis important?

if your body gets outside homeostasis than enzyme's can't maintain that environment, organ systems fail.

What would happen to a cell placed in an isotonic solution? A hypotonic solution? A hypertonic solution?

isotonic- cell doesn't change size at equilibrium hypotonic- cell gains water and swell hypertonic- cell loses water and shrinks at equilibrium

Acetylocholine? What are the differences in effects between nicotinic and muscarinic cholinergic receptors?

it activates CHOLINERGIC RECEPTORS(neurons that secrete ACh and receptors that bind ACh) *can exhibit or inhabit 1- Nicotinic chlonergic receptors: they are monovalent cation channels- allows anything with +1 charger to enter. allows passage of Na+ and K+(more Na+ in due to steeper electrochemical gradient) *Found is autonomic nervous system ganglia; stimulates post ganglionic neurons and skeletal muscle fibers(neuromuscular junctions) 2- Muscarinic cholinergic receptors: 5 subtypes are all linked to G-protein coupled receptors *contracts smooth muscle, stimulates gland secretion and slows heart rate.

What is Tonicity?

it's a comparative term to describe a solution based on how that solution would affect the volume of a cell placed in that solution.

What is homeostasis? Why is it important to maintain homeostasis?

it's a maintenance of a relatively stable internal environment. Its NOT a constant internal environment its a DYNAMIC STEADY STATE.

What role does the hypophyseal portal system play in stimulating the anterior pituitary? How are they released?

its a network of capillaries that shuttle hormones into the anterior pituitary. The arrangement of capillaries and its portal veins allows a small number of secretory neurons in the hypothalamus to control the anterior pituitary. Secretion is controlled by neurohormones from the hypothalamus, which are carried to the anterior pituitary via the hypophyseal portal system. 1. Neurons synthesizing trophic neurohormones release them into capillaries of portal system 2. portal vessels carry trophic neurohormones directly to the anterior pituitary, where they act on endocrine cells 3. endocrine cells then release their peptide hormones into the second set of capillaries for distribution of the rest of the body.

receptor enzyme

ligand binds to a receptor-enzyme that activates an intracellular enzyme. ex. insulin binding

integrin receptor

ligand binds to the integrin receptors and alters enzymes or the cytoskeleton.

G-protein coupled receptor

ligands binds to a g-protein coupled receptor and opens an ion channel or alters enzyme activity.

How might the extracellular concentration of K+ affect the resting membrane potential of a neuron and its relative sensitivity to stimuli?

normal concentration: 3.5-5 mol/l HYPERKALEMIA- increase in blood K+(more K+ in the ECF) *K+ will want to stay in the cell to make it more positive, which creates more action potentials *Resting membrane potential would then be closer to the threshold and neurons will fire action potentials in response to small graded potentials. HYPOKALEMIA- decrease in blood K+(less K+ in the *more K+ will want to exit the cell, which makes it more negative and harder to create action potentials *resting membrane is farther from threshold and neurons need larger graded potentials to fire action potentials *this often shows up in muscle weakness, because action potentials aren't being sent.(neurons that are controlling skeletal muscles are not firing normally due to low action potentials)

How can a single type of signaling molecule have different effects in different tissues?

one ligand may have multiple receptors. the target cell response depends on its receptor or its associated intracellular pathways, not on the ligand. ex- epinephrin can bind to different adrenergic receptor isoforms in the two tissues.

positive feedback?

respinse reinforces original stimulus; destabilizes system and requires outside intervention to be stopped. ex. child birth, platelets activation and lactation.

micelles

single layer of lipids helpful for digestion

chemical/electrical disequilibrium

some solutes are more concentrated on one side of the membrane than others. *CHEMICAL- usually certain chemical makeups that are unequal on both sides. (Different solutes) *ELECTRICAL- uneven ion distribution(different ion charges)

What are some ways that an action potential is different than a graded potential? In which part of the neuron is each produced?

strength of stimulus- graded potentials depend on the initial stimulus, can be summed. Action potential is an all or non phenomenon; can't be summed. initiates signal: graded potentials are initiated by entry of ions through gated channels. action potential is initiated above threshold graded potential at the trigger zone opens ion channels. action potentials can travel long distances, graded potentials decrease strength as they travel. graded potentials happen within the dendrites and the cell body, or less frequently near the axon terminal.

What is an equilibrium potential? What are the equilibrium potentials of Na+ and K+?

the membrane potential that exactly opposes the concentration gradient of a given ion. Na+ is 60+ and K+ is -90 but flow in a way to offset back to -70mV.

How is the pituitary gland structured?

the pituitary gland is a lime bean structure that extends downward from brain connected to it by a think stalk that involves fusion of two tissue types: ANTERIOR PITUITARY- true endocrine gland that is derived from embryonic tissue that formed the roof of the mouth(referred to as adenohypophysis) POSTERIOR PITUITARY(neurohypophysis)- extension of neural tissue from the brain; secretes neurohormones produced by the HYPOTHALAMUS(releases signals from all over the body)

steroid hormones

these are derived from cholesterol *source is more limited: cortex of adrenal glands, gonads, and placenta(during pregnancy) *Examples: aldosterone, cortisol, androgens and estrogen

peptide hormones

these range from residues of 3 amino acids to large proteins or glycoproteins *encompasses majority of hormones *EXAMPLES: INSULIN, OXYTOCIN, PROLACTIN, ERYTHOPOETIN

chemical synapses

these utilize neurocrine molecules(most common way) electrical signal is converted into a chemical signal(neurocrine) that crosses the synaptic cleft and binds to a receptor on its target cell.

How are the peptide hormones signals transduced?

they are water soluble and therefore generally dissolve easily in the extracellular fluid for transport throughout the body. HALF LIFE- is short(several minutes), if the response to a peptide hormone needs to be sustained, then it must be secreted continually. bind to surface receptors because they are LIPOPHOBIC often act through cAMP second messengers

In what ways can cells communicate over long distances? How do these methods differ from one another? How might they be similar?

this takes place through LONG-DISTANCE COMMUNICATION. which is often through the endocrine and nervous systems. *endocrine systems uses HORMONES- secreted into blood and carried throughout the body. *nervous system uses a combination of chemical and electrical signals. electrical signal travels along a NEURON. *hormones persist for a longer period of time after release than paracrine and autocrine signals.