Physiol Exam 1: Chps. 1-7, 9 Flashcards
a. Distinguish: atoms vs. molecules vs. ions (including cations & anions)
b. Identify examples of each: atoms vs. molecules vs. ions (including cations vs. anions)
a. Atoms: smallest particle of an element that retains the characteristic of chemical properties
Molecules: group of chemically combined atoms (at least 2)
Ions: atoms or molecules that have a + or - charge (due to unequal # of protons and electrons)
* Cations: positively charged ions
* Anions: negatively charged ions
b. Atoms: H
Molecules: H2O
Ions: Al2S3, Ca3N2
* Cations: Na+, K+, H^2, Ca^2, NH4+
* Anions: Cl-, HCO3-, PO4^3-
a. Name the 4 categories of macromolecules
b. Identify examples of each macromolecule category
- Carbohydrates - Glucose, fructose, lactose, sucrose, glycogen, starch, fiber
- Nucleic Acids - DNA, mRNA
- Lipids - Cholesterol, fatty acids, phospholipids, triglycerides
- Proteins - Enzymes, channels, pumps
Define enzyme, describe its function & name some characteristics essential to its function
Enzymes: catalytic proteins for anabolic (build) or catabolic (break) reactions
* Function: ↑ rate of a reaction (by ↓ activation energy)
— Specificity
— Not used up (reused)
Name the 5 types of membrane proteins (including sub-types) & describe each of those membrane protein’s function
- Enzyme: degrades chemical messenger, terminating its effect
- Cell-identity marker: glycoprotein that helps distinguish body’s own cells from foreign cells
- Receptor: binds to chemical messengers (ex. hormones)
4a. Leakage channel: constantly open; tunnel allows substances to pass into & out of cell
4b. Gated channel: opens & closes to allow substances through at certain times - Carrier: bind to glucose, ions & other substances to transfer them to other side of cell
Define homeostasis; define set point; name the type of feedback that most often maintains vs. opposes homeostasis
Homeostasis: dynamic constancy of the internal environment
Set point: average
Negative feedback - mostly maintain homeostasis
Positive feedback - opposes homeostasis
Name the 5 common components of a feedback loop, memorize how they are sequenced & describe each component
- Stimulus: A change in the body or environment
- Sensor/receptor: Inside body detecting change (always active) & sends info to…
- Integrating center: Assesses change around a set point & sends instructions
- Effector: Carries out instructions of integrating center
- Response
Describe negative feedback
Counteracts the change
Memorize the details of the 2 negative feedback loops for thermoregulation
a) Body Temperature Fall BELOW Normal
1. Stimulus - Cold environmental temps. lower body temp. to below normal
2. Receptor - Sensory receptors in skin detect cold, sending information to brain
3. Integrating center - Hypothalamus of brain compares sensory input regarding temperature decrease to normal set point of 37 C
4. Effectors - BV in skin constrict; sweat glands become inactive; skeletal muscles shiver to generate heat
5. Response - Body temperature returns to normal
b) Body Temperature Rises Above Normal
1. Stimulus - Exercise or hot environmental temps raise body temp. to above normal
2. Receptor - Sensory receptors in skin detect heat, sending information to brain
3. Integrating center - Hypothalamus of brain compares sensory input regarding temperature decrease to normal set point of 37 C
4. Effectors - BV in skin dilate; sweat glands secrete sweat, which, if evaporated, will cool the skin’s surface
5. Response - Body temperature returns to normal
Describe antagonistic effectors & their purpose
Homeostasis often maintained by opposing effectors moving conditions in opposite directions = finer control
— Effectors that do the opposite of one another to help fine tune and regulate the responses around the set point to maintain homeostasis; effectors that help us get to the set point quicker
Describe positive feedback
Positive feedback: A change in normal value that is amplified or accelerated
— Continues the change
Distinguish positive feedback from negative feedback
Negative feedback - counteracts the change
Positive feedback - continues the change
Recognize examples of negative vs. positive feedback
Negative feedback:
* Thermoregulation
Positive feedback :
* Child birth
* Breast feeding
Memorize the details of the negative feedback loop for blood pressure regulation involving the nervous system
Lying down
1. Stimulus - Standing up = BP falls
2. Sensor - BP receptors respond
—> Sensory nerve fibers
3. Integrating center - Medulla oblongata of the brain
—> Motor nerve fibers
4. Effector - HR increases
5. Response - Rise in BP
Memorize the details of the 2 negative feedback loops for blood sugar regulation involving the endocrine system (hormones)
A) Eating
1. Stimulus -↑ glucose
2. Sensor - Pancreatic islets (of Langerhans)
3. Integrating center - Pancreatic islets (of Langerhans)
— compare it to set point (~70-140 mg/dL after a meal)
4. Effector - Pancreatic islets (of Langerhans) and ↑ insulin
— ↑ Cellular uptake of of glucose
5. Response - ↓ Blood Glucose
B) Fasting
1. Stimulus - ↓ Blood Glucose
2. Sensor - Pancreatic islets (of Langerhans)
3. Integrating center - Pancreatic islets (of Langerhans)
— compare it to set point (~70-100 mg/dL during fasting)
4. Effector - Pancreas ↓ Insulin, ↑ Glucagon, targeting the liver
— ↓ Cellular uptake of glucose; ↑ Glucose secretion into blood by liver
5. Response - ↑ Blood glucose
Memorize how water is distributed amongst the ICF, ECF, interstitial fluid & plasma
ICF = 2/3
ECF = 1/3
- Interstitial fluid = 80%
- Blood plasma = 20%
Define selectively permeable for cell membranes
Selectively permeable: some particles (certain ions) can go in/out
Distinguish non-carrier mediated transport from carrier-mediated transport & identify examples for each type of transport
Non-carrier mediated: transport does NOT require membrane protein carriers
* Simple diffusion of lipid-soluble molecules
* Simple diffusion of ions through membrane channel proteins
* Osmosis through membrane water channel proteins
Carrier-mediated: transport requires membrane protein carriers
* Facilitated diffusion = passive transport
(no ATP)
* Active transport = ATP required
* Specific carrier proteins called pumps
Distinguish passive transport from active transport
Passive transport = No ATP
Active transport = ATP
Define diffusion & describe how a concentration gradient drives it
Diffusion: net movement of particles (molecules or ions) from regions of higher to regions of lower concentration
* Due to concentration gradient; higher the concentration gradient, the faster the rate of diffusion
* Continues until no difference = NO net diffusion
Describe the types of particles that the cell membrane is permeable & identify examples for the different types
Permeable to:
1. Non-polar (Lipid-soluble AKA hydrophobic) molecules, small & large
* Ex. steroid hormones & O2
2. Small molecules with polar bonds but uncharged
* CO2, ethanol & urea
3. Small amounts of H2O
Describe the types of particles that the cell membrane is impermeable to & identify examples for the different types
IMpermeable to:
1. Large polar (Charged AKA hydrophilic) molecules: carbohydrates (ex. glucose) & amino acids (& their polymers)
* Require carrier proteins
2. Charged inorganic ions (Na+,K+,Cl-,Ca^2+ )
* Require ion channels
- Leakage
- Gated
Describe the 4 factors that affect rate of diffusion through a cell membrane
Depends on:
1. Concentration difference
* “Steep” (high rate) vs. “shallow” (low rate)
2. Cell membrane permeability
* Ex. At rest, neuron cell membrane 20x more permeable to K+ than to Na+
3. Temperature (T)
* Higher T = faster
4. Surface area
* Microvilli; Alveoli
Define osmosis & describe the 2 requirements needed for osmosis
Osmosis = Water
* Net DIFFUSION of H2O across selectively permeable membrane from high [H2O]→low [H2O] where H2O=Solvent
* Requirements:
1. Solute at different concentration across membrane
2. Membrane relatively impermeable to solute
- Osmotically active = Solute that can NOT pass freely through membrane
Describe osmotic pressure & osmotically active. How are they related to each other?
— Osmotic pressure: force exerted to stop osmosis; indicates how strongly H2O wants to diffuse
— Osmotically active = Solute that can NOT pass freely through membrane
* Osmotic pressure is proportional to osmotically active solute concentration
Memorize the range (& unit in Osm & mOsm) for plasma osmolality (blood)
- Plasma osmolality ~0.3 Osm or ~300 mOsm
- Range: 275-295 mOsm
Convert the concentration of solutions into molality & osmolality
EX) Since electrolytes ionize in water,
*1 mol NaCl → 1 mol Na+ (+) 1 mol Cl-
*1 m NaCl = 2 Osm
Describe the 3 characteristics that carrier proteins exhibit
- Specificity: Interact with specific molecule(s) only
- Competition: Molecules with similar chemical structures compete for carrier site; rate of transport is affected
- Ex. Amino acids
- Saturation: All carrier sites filled = Transport Maximum (Tm)
Define transport maximum
All carrier sites filled = Transport Maximum (Tm)
- carrier proteins working at maximum speed
Define facilitated diffusion
Facilitated diffusion: Carrier-mediated transport of particles through the cell membrane along/down concentration gradient
Name the cells that contain GLUT4 carriers & describe how GLUT4 carriers are inserted into the cell membrane from the cytoplasm
- Location: muscle cells and adipocytes
- In unstimulated muscle cell, GLUT4 within membrane of a cytoplasmic vesicle
- In stimulated muscle cell, vesicle fuses with cell membrane
- Due to:
- exercise OR
- insulin
- Result: More glucose into muscle via facilitated diffusion
Define active transport & name the 2 requirements
Active transport: Movement of molecules & ions against their concentration gradients; “Uphill”: from [lower] to [higher]
* Requires both
1. Carrier protein
2. ATP
Define primary active transport & name the energy source that powers it
Primary active transport: uses carrier proteins that changes shape
— DIRECTLY uses ATP to transport molecules up/against its concentration gradient
Name the ions exchanged, the amounts exchanged & their starting & ending locations for the Na+/K+ pump
Overall: Exchanges 3 Na+ out for 2 K+ in
Describe the 3 purposes of the Na+/K+ pump
- Na+ gradient as energy for moving other molecules (important for secondary active transport)
- Electrochemical signals in muscles & nerves
- Osmotic reasons
Define secondary active transport & name the energy source that powers it
Secondary active transport: Energy for uphill (against) movement of a particle (ex. glucose) comes from downhill transport of Na+
— ATP powers it indirectly
Distinguish primary active transport from secondary active transport
Primary active transport: Directly uses ATP
Secondary active transport: Indirectly uses ATP
Distinguish symport from antiport & identify examples for each type of transport
Symport: Molecule or ions move in same direction as Na+
*Ex. Glucose-Na+
Antiport: Molecule or ions move in opposite direction as Na+
*Ex. Na+-H+
Distinguish apical surface from basolateral surface for epithelial membranes
Apical surface: faces lumen; 2 K+ in
Basolateral surface: faces inside of body; 3 Na+ out
Distinguish endocytosis from exocytosis
Endocytosis: In
* Includes receptor- mediated endocytosis (specific)
Exocytosis: Out
Describe receptor-mediated endocytosis
Receptor-mediated endocytosis: specific, a certain particle (LDL, cholesterol) has to bind to a receptor in order to enter the cell
Define membrane potential & describe how certain particles create it (4)
Membrane potential: difference in charge across cell membrane
*Fixed anions: proteins & phosphates that can’t leave
* Attract cations
*K+most permeable
- More K+ in (150 mEq/L) vs. out (5)
* Na+/K+ pumps: 3 Na+ out for 2 K+ in
• Constantly “pumping” in the background unless there is no ATP available
Describe the charge on the inside vs. outside of the cell membrane
Inside of cell membrane = Negative
Outside of cell membrane = Positive
Define equilibrium potential
Equilibrium potential: theoretical voltage across membrane if only 1 ion allowed to diffuse through membrane
Memorize the value (&unit) for EK vs. ENa
K+ equilibrium potential (EK):
Potential difference if K+ only diffusible ion = -90 mV for given [K+] inside vs. out
Na+ equilibrium potential (ENa):
Potential difference if Na+ only diffusible ion = + 66 mV [Na+] inside vs. out
Compare the extracellular vs. intracellular concentrations of Na+, K+, Cl- & Ca2+ ions
Intracellular - Extracellular
Na+ = 12 mM - 145 mM
K+ = 150 mM - 5 mM
Cl- = 9mM - 125 mM
Ca2+ = 0.0001 mM - 2.5 mM
Define resting membrane potential (RMP)
Resting membrane potential: > EK of -90 mV because:
1. Some Na+ can diffuse across cell membrane into cell
2. K+ diffusion out of the cell
* RMP = -70 mV
Memorize the value (& unit) for RMP of a typical neuron & describe how certain particles create it
RMP = -70mV inside the cell membrane vs. outside
* Range: -65 mV to -85 mV
Why?
1. Some Na+ can diffuse across cell membrane into cell
2. K+ diffusion out of the cell
Distinguish paracrine vs. synaptic vs. endocrine signaling
- Paracrine signaling: to target cells (of the same organ)
- EX) Paracrine - Synaptic signaling: neurons regulate target cells
- EX) Neurotransmitter - Endocrine signaling: regulators travel in the blood to target cells
- EX) Hormones
Identify examples of nonpolar vs. polar regulatory messenger/molecules
Nonpolar Chemical Messengers - Steroid hormones (estrogen, testosterone, progesterone, cortisol), Thyroid hormones (T3 & T4), NO
Polar Chemical Messengers - Epinephrine, Norepinephrine, ACh, Insulin
Distinguish the location(s) for the receptor proteins for nonpolar vs. polar regulatory molecules
Nonpolar’s receptor - In cytoplasm OR nucleus
Polar’s receptor - Cell membrane
Describe the events that occur after a nonpolar vs. polar regulatory molecule binds to its receptor
Nonpolar - Regulate gene transcription/ translation
Polar - 1st messenger binds to receptors on the cell membrane, and activates the 2nd messenger with signal transduction
— Signal transduction: transmission of info from 1 side of a membrane to the other using membrane proteins
Name examples of 2nd messengers, describe how they perform their action & describe their purpose
- Examples: ions (Ca2+) or molecules produced within cytoplasm (cyclic AMP, cAMP)
- Action: Enter cytoplasm to mediate actions of regulatory molecules
*Purpose: Amplify signals
Memorize the details of the negative feedback loop for blood osmolality regulation: dehydration
- Stimulus - Dehydration: ↓ Blood volume, ↑ Plasma osmolality
- Sensor - Osmoreceptors in the hypothalamus
- Integrating center - Osmorecpetors in the hypothalamus
— Compares it to the set point (range: 275-295 mOsm) - Effector - ADH secretion from posterior pituitary gland (thirst) → kidneys (help reabsorb water)
- Response - ↑ Water intake, ↑ Water retension
Distinguish isotonic vs. hypotonic vs. hypertonic solutions & describe the effect on a cell’s volume when the cell is placed in each solution
- Isotonic solutions: “equal tension”
— RBCs in isotonic sol. will not gain or lose H2O
— EX of isosmotic solution:
• Normal saline (0.9 g NaCl per 100 ml sterile water)
• Ringer’s lactate
• 5% dextrose AKA D5W (5 g glucose per 100 ml sterile water) but hypotonic when given to a patient - Hypotonic solutions: Fewer osmotically active solutes & lower osmotic pressure than plasma
— RBC: will expand; possibly burst (hemolyse) - Hypertonic solutions: More osmotically active solutes & higher osmotic pressure than plasma
— RBC: will shrink (crenate)
Define hemolyse/hemolysis vs. crenate/crenation
Hemolyse: will expand; possibly burst
Crenate: shrink
Distinguish neurons vs. neuroglia in terms of their function & prevalence
Neurons: conducts action potentials (AP)
* Mostly can NOT divide by mitosis
Neuroglia: support
* More abundant (5x more neuroglia than neurons)
Distinguish the dendrite vs. cell body vs. axon of the neuron
Dendrite: receive chemicals & transmits electrical signals to the cell body.
Cell body: contains nucleus (organelle) & Nissl bodies
Axon (nerve fiber): conducts APs away from the cell body
Distinguish sensory neuron vs. motor neuron vs. interneuron
- Sensory neuron
— Receptors → CNS
— EX) Dorsal root ganglion - Motorneuron
— CNS → Effector (muscle, gland)
— Somatic motor neuron vs. (pre ganglionic neuron) autonomic motor neuron (post ganglionic neuron)
— EX) Lateral horn of spinal cord - Interneuron
— Entirely within CNS
Identify the 2 neuroglia that belong in the PNS vs. 4 in the CNS
PNS Neuroglia:
1. Schwann cells
2. Satellite cells
CNS Neuroglia:
1. Oligodendrocytes
2. Microglia
3. Ependymal cells
4. Astrocytes
Describe the function(s) of each neuroglia in the PNS
- Schwann cells - insulation and regeneration for axons
- Satellite cells - insulate and regulate chemical environment of the cell body
Describe the function(s) of each neuroglia (4) in the CNS
- Oligodendrocytes - insulation
- Microglia - Phagocytose foreign and degenerated material (dendrites or bad myelin)
- Ependymal cells - secrete CSF
- Astrocytes - form tight junctions = blood-brain barrier
• Uptake glucose → lactate
• Recycle neurotransmitter - Ex: glutamate (Glu) to glutamine (Gln)
• Regulate ECF K+ in brain
• Form CNS synapses
Compare the number of axon(s) each Schwann cell surrounds vs. each oligodendrocyte
Schwann cells - ONE per axon
Oligodendrocytes - Covers SEVERAL axons
Define graded potentials, name the locations they are produced & describe the 2 types that can be produced
- Graded Potential: a change in the membrane potential with amplitudes that are varied based on stimulus intensity
- Location: Dendrite and cell body
- Types:
1. Excitatory (makes membrane potential positive)
OR
2. Inhibitory (makes membrane potential negative)
Memorize the value (and unit) for the threshold membrane potential for a neuron
Threshold membrane potential = -55 mV
Distinguish depolarization vs. repolarization vs. hyperpolarization
Depolarization: RMP goes ↑ = more positive or less negative
Repolarization: return to RMP
Hyperpolarization: RMP goes ↓ = more negative or less positive
Describe the 2 types of channels found on the axon cell membrane & identify the ion that moves through each type of channel
- Non-gated channels
* Leakage channels: for K+ - Gated channels
* Voltage-gated channels: for Na+
— 1. activation gate
— 2. inactivation gate
* Voltage-gated channels: for K+
— 1. activation gate
Distinguish when a channel is closed vs. open vs. inactivated & identify the status of the activation & inactivation gates for each channel situation
Closed (at RMP, -70 mV):
* Activation gate blocking
* Inactivation gate open
Open (caused by depolarization [-55 mV])
* Activation gate open
* Inactivation gate open
Inactivated (during refractory period)
* Activation gate open
* Inactivation gate blocking
Define electrochemical gradient
- Electro - Ion goes from an environment that’s positive → an environment that’s negative
- Chemical - High concentration of ion → low concentration of ion
Memorize the details of the depolarization phase of the AP
- Na+ moves down electro- chemical gradient = inward (influx)
- Eventually channel becomes inactivated
Memorize the details of the repolarization phase of the AP
- K+ moves down electrochemical gradient = outward (efflux)
- After- hyperpolarization: channels stay open just a bit longer
Define the all-or-none law & describe how it affects the duration & amplitude of all AP
- AP ALWAYS same amplitude or NONE produced (all-or-none law)
- All AP have ~ the same:
— Duration (time): due to inactivation of Na+ channel
— Amplitudes: concentration gradient of Na+; amt. of Na+ enters is consistent = AP always the same
Describe how the nervous system determines the quality vs. quantity (2 methods for quantity) of a stimulus
What kind of stimulus is it? (Quality)
* Labeled line code: each axon to the brain leads from a receptor that recognizes a particular stimulus type
- Axons in optic nerve = provides info on light receptors in the eye
How intense is the stimulus? (Quantity)
1. Recruitment:
* Neurons with lower threshold fire 1st
* Stronger stimuli activate neurons with higher threshold
2. Within a neuron, ↑ frequency of AP (# per unit time) = greater stimulus strength
* Ex: Warm vs Hot
Distinguish absolute vs. relative refractory period & describe when and why each period occurs
Absolute refractory period: Axon CANNOT produce new AP
— Occurs during depolarization and repolarization of AP, thus voltage gated Na channels aren’t activated
Relative refractory period: Axon CAN produce new AP but requires stronger stimulus
— Occurs after hyperpolarization, but very difficult to produce another AP, due to K+ diffusing
Compare graded potentials to AP’s in terms of location produced in the neuron, threshold, gradation, summation & refractory period
Graded potential:
- Location: Dendrite and cell-body
- Threshold: no
- Graded: yes
- Summation: yes
- Refractory period: no
Action potential:
- Location: axon’s cell membrane
- Threshold: yes (-55mV)
- Graded: no; “all or none”
- Summation: no; voltage gated channel is inactive
- Refractory period: yes; absolute (no AP) and relative refractory period (possible but difficult to make AP)
Describe the propagation of action potentials after they are generated
1 AP does NOT travel entire axon
- New AP has to be made
Distinguish the propagation of APs on unmyelinated axons
- Depolarization (Na+ influx) → new depolarization @ adjacent axon with voltage-gated channels → new AP
- Propagate along entire length
- Conducted without decrement/diminished (AP will continue till the end)
- Velocity: slow, ~1 m/s (2.23 miles/hr)
Distinguish the propagation of APs on myelinated axons
- Myelin = insulation; no APs
- Nodes of Ranvier (about 1-2 mm away from each other) with voltage-gated Na+ & K+ channels for APs
- Node-to-node = saltatory conduction (signal jumps from one node to another)
- Velocity: fast, >100 m/s (223 miles/hr)
Name the 2 factors that influence conduction speed of an AP & describe how each factor affects the speed
- Presence of myelination
- Thicker axon/ axon with a larger diameter
- less resistance inside axon
- is also myelinated
Define synapse and the types
Synapse: functional connection between neuron & 2nd cell
* Neuron → neuron (dendrite, cell body or axon)
* Neuron → effector (gland or muscle)
* If muscle = neuromuscular junction AKA neuromuscular synapse
1. Electrical synapse
2. Chemical synapse
Describe electrical synapse and the different types of substances that travel through it
- Occurs at gap junctions
- 6+6 connexin proteins form water- filled channels that join electrically & mechanically
- Ions & molecules can pass
- APs can cross gap junction:
- Cardiac muscle
- Smooth muscle
- 6+6 connexin proteins form water- filled channels that join electrically & mechanically
- Other locations:
- Neuroglial cells (Ca2+ )
Memorize the details of how an AP leads to the release of neurotransmitters into the synaptic cleft
- AP reaches presynaptic terminal bouton
— Open voltage-gated Ca2+ channels
— Ca 2+influx & binds to synaptic vesicles with neurotransmitter
— Vesicles fuses with membrane & exocytosis neurotransmitter - Exocytosis requires ATP
Describe the effect of altering the number of APs in a neuron has on neurotransmitter release by that neuron
This process of chemical synapse applies to how many neurotransmitters are released
* In general, more APs → more neurotransmitters exocytosed
Distinguish agonists from antagonists
- Agonist: a particle different than the neurotransmitter that can bind to & activate the receptor
- Antagonist: a particle different than the neurotransmitter that can bind to & reduce the activity of the receptor
Define cholinergic fibers, cholinergic receptors & cholinergic synapses
Cholinergic = ACh
* Cholinergic fiber - the axon that releases ACh as a neurotransmitter
* Cholinergic receptor - the receptor that receives ACh
* Cholinergic synapse - a location where the axon that releases ACh makes a connection with another target cell
What are monoamine neurotransmitters made from and name examples of monoamines
- From amino acids
- Catecholamines: from precursor tyrosin
1. Dopamine
2. Norepinephrine (functions as neurotransmitter & hormone)
3. Epinephrine (functions as hormone only)
- Histamine: from precursor histidine
- Serotonin: from precursor tryptophan
Define adrenergic fibers, adrenergic receptors & adrenergic synapses
Adrenergic = Norepinephrine
* Adrenergic fiber - the axon that releases norepinephrine as a neurotransmitter
* Adrenergic receptor - the receptor that receives norepinephrine
* Adrenergic synpase - a location where the axon that releases norepinephrine makes a connection with another target cell
Memorize the type of neurotransmitter dopamine is (excitatory or inhibitory)
Inhibitory neurotransmitter for midbrain neurons
Name the enzyme that degrades monoamines & name its specific location
monoamine oxidase (MAO) in presynaptic terminal bouton
Identify the amino acid neurotransmitters considered excitatory (1) vs. inhibitory (2) & describe how these inhibitory neurotransmitters produce inhibition
Excitatory:
GLUTAMATE
- NMDA receptor (memory)
- AMPA receptor (possibly memory)
- Kainate receptor
Inhibitory: Cl- goes in making cell inside more negative
1. GABA: IPSP via Cl- channels
- Role: motor functions in cerebellum
- Most common neurotransmitter in brain; (Huntington’s disease)
2. Glycine: IPSP via Cl- channels
- Role: help control skeletal movements (inhibits antagonistic muscle)
Identify the most common neurotransmitter in the brain
GABA
- Role: motor functions in cerebellum
Describe the function(s) and what it’s made from for the following neurotransmitters: substance P, nitric oxide
Substance P for pain sensations
- polypeptides as neurotransmitters
Nitric oxide (NO) ; gases as neurotransmitters
- crosses cell membrane easily
- CNS: made by presynaptic & postsynaptic neurons
- PNS: autonomic neurons targeting smooth m. to relax
- Endothelial cells (blood vessel) to smooth m., causing vasodilation
- Macrophages use to kill bacteria
Distinguish divergence from convergence
Divergence: 1 neuron synapses w/ many
Convergence: many neurons synapse on 1
Distinguish spatial summation from temporal summation
Spatial summation: Release of neurotransmitters from 2 presynaptic neurons to reach threshold (-55 mV)
Temporal summation: Successive release of neurotransmitter from one presynaptic neuron that reaches threshold (-55 mv)
Name the 2 divisions of the ANS & the 4 general effectors each division innervates
Sympathetic division and Parasympathetic division
1. Smooth muscle
2. Cardiac muscle
3. Endocrine glands
4. Exocrine glands
Name the neurotransmitter(s) released by sympathetic vs. parasympathetic preganglionic neurons
ALL ANS preganglionic fibers releases ACh
Name the neurotransmitter(s) released by sympathetic vs. parasympathetic postganglionic neurons
- Most postganglionic sympathetic fibers use NE, and some ACh
- Most postganglionic parasympathetic fibers use ACh, and some NO
Distinguish the action that sympathetic vs. parasympathetic nerves produce on the following: radial m. (Iris), circular m. (iris),
Sympathetic:
* Radial m. - Contracts (dilate pupil)
* Circular m. - None
Parasympathetic:
* Radial m. - None
* Circular m. - Contracts (constrict pupil)
Distinguish the action that sympathetic vs. parasympathetic nerves produce on the following: SA node
Sympathetic: Increases heart rate
Parasympathetic: Decreases heart rate
Distinguish the action that sympathetic vs. parasympathetic nerves produce on the following: cardiac m. (heart)/ contractility
Sympathetic: Increases
Parasympathetic: Decreases (atria)
Distinguish the action that sympathetic vs. parasympathetic nerves produce on the following: skeletal m. vessels
Sympathetic: Relaxes (vasodilation)
Parasympathetic: None
Distinguish the action that sympathetic vs. parasympathetic nerves produce on the following: bronchiolar smooth m.
Sympathetic: Relaxes (bronchodilation)
Parasympathetic: Contracts (bronchoconstriction)
Distinguish the action that sympathetic vs. parasympathetic nerves produce on the following: GI tract smooth m. in walls,
Sympathetic: Relaxes
Parasympathetic: Contracts
Distinguish the action that sympathetic vs. parasympathetic nerves produce on the following: GI tract secretion,
Sympathetic: Inhibits
Parasympathetic: Stimulates
Distinguish the action that sympathetic vs. parasympathetic nerves produce on the following: urethral sphincter
Sympathetic: Contracts
Parasympathetic: Relaxes
Distinguish the action that sympathetic vs. parasympathetic nerves produce on the following: sweat glands for thermoregulation
Sympathetic: Increases
Parasympathetic: None
Name the structure that is considered a modified sympathetic ganglion & identify the type of innervation it receives
Adrenal medulla
— Receives ONLY preganglionic innervation
Identify the 4 cranial nerves associated with the parasympathetic division
Cranial nerve III, VII, IX, X
Name the locations where α1 vs. β1 vs. β2 adrenergic receptors are found & describe the action produced by each receptor when stimulated (use the bulletpoint information & NOT table 9.4)
▪ a1 : Blood vessels; Constricts smooth m. in blood vessels & gut (vasoconstriction)
▪ b1 : Heart; ↑ HR + contraction strength of heart
▪b2 : Lungs; Relax smooth muscle in bronchioles
Memorize the details of the mechanism after a β adrenergic receptor is stimulated (1.at the heart & 2. at the bronchioles) vs. an α adrenergic receptor is stimulated (at blood vessels)
β Adrenergic Receptors
1. Epinephrine OR Norepinephrine binds to its (adrenergic) receptors
2. G-proteins subunits dissociate and one of the subunits go to a membrane protein/enzyme, adenylate cyclase
3. Adenylate cyclase is activated; breaks ATP into cyclic AMP
4. Cyclic AMP activates protein kinase , which opens ion channels:
* β1 at heart: HCN channel (for Na+)
* β2 bronchioles: K+ channel
α1 Adrenergic Receptors
1. Epinephrine OR Norepinephrine binds to its (adrenergic) receptors
2. G-proteins subunits dissociate and one of the subunits go to a membrane protein/enzyme, Phospholipase C
3. Phospholipase C take a phospholipid from the cell membrane and turns it into 2 different molecules, DAG and IP3
— IP3 travels into cytoplasm to the endoplasmic reticulum to help release Ca+ into the cytoplasm
4. Ca binds to calmodulin→
* Activates protein kinases
* α1 at blood vessels = vasoconstriction
Name the locations in the body for nicotinic cholinergic receptors (3)
- Neuromuscular junctions (neuron and skeletal muscle)
- autonomic ganglia (preganglionic and postganglionic)
- some CNS
Identify the effect on membrane potential after ACh binds to the nicotinic receptor & describe the ions & their movement that permit this effect
- General effect: ALWAYS excitatory; membrane potential is +
- Opens Na+/K+ ion channel w/in protein
— More Na+ in than K+ out = depolarization → excitation
Name the agonist vs. antagonist of the nicotinic receptor
Agonist - Nicotine
Antagonist - Curare
Name the locations in the body for muscarinic cholinergic receptors
Most parasympathetic axons to effectors
Identify the effects on membrane potential after ACh binds to muscarinic receptors & describe the mechanism to produce this effect
- General effect: EITHER excitatory or inhibitory
— there are different subtypes/ 5 types of muscarinic receptors: M1-M5
Name the agonist vs. antagonist of the muscarinic receptor
Agonist: Muscurine
Antagonist: Atropine
Name the enzyme that degrades ACh & name its specific location
Acetylcholinesterase (AChE)
- found in post-synaptic membrane/cell
Name 3 neurotransmitters released by nonadrenergic, noncholinergic postganglionic fibers
- ATP
- vasoactive intestinal peptide (VIP)
- nitric oxide (NO)
Define duel innervation
Most visceral organs receive dual innervation = innervation from both divisions (sympathetic and parasympathetic)
Name the 4 structures & organs that receive only sympathetic innervation
- Adrenal medulla
- Arrector pili
- Sweat gland
- Most blood vessels
Describe the functions of the medulla oblongata
Medulla oblongata regulates the visceral reflexes from visceral functions
