Physiology Midterm Flashcards
Chapters 1-9
Physiology is defined as
the study of how animals work. This includes the structure and function of various parts, diversity of animals, and unifying themes.
Levels of biological organization
atoms, molecules, cells, tissues, organs, organ systems, organisms, populations, communities, ecosystems, and biosphere.
physiological subdisciplines
cell and molecular physiology, system physiology, organismal physiology, ecological physiology, integrative physiology.
Unifying themes of Physiology
A) physiological processes obey physical and chemical laws. B) physiological processes are usually regulated: regulation is a central theme in physiology. C) physiological phenotype is a product of genotype and phenotype. D) Genotype is the product of evolution.
Homeostasis
maintenance of internal constancy: negative feedback and positive feedback systems are frequently major players in homeostatic mechanisms.
Positive and negative feedback
Negative feedback works against body change. Examples are both body temperature and blood sugar regulation. Positive feedback works towards body change. An example is blood clotting.
Genotype
genetic makeup
Phenotype
morphology, physiology, and behavior
Physical properties of cell and tissue are linked to
structure and function
Molecular interactions are governed by
chemical laws both thermodynamic and kinetic
___ describe membrane function; especially excitable cells
Electric laws
___ influences physiological patterns
Body Size
Name 2 strategies for coping with changing conditions.
Conformers and Regulators
Conformers
Allow internal conditions to change with external conditions.
Regulators
Maintain relatively constant internal conditions regardless of external conditions.
Equilibrium
no net change or dissipation of energy.
Steady state
no net change, but continuous dissipation of energy or matter.
Life is a ___ process
Steady state. Animals continuously dissipate energy to keep away from equilibrium.
Phenotypic plasticity
single genotype generates more than one phenotype depending on environmental conditions.
____ contain a surprising amount of membrane
animal cells
The ___ is about 5-10nm thick: fluid-mosaic model
plasma membrane
Cell Membrane Structure
membrane, lipid, membrane lipid, membrane proteins
Membrane
lipid-protein assemblies held togethor in thin sheet by noncovalent bonds.
Lipid
Protein ratio varies greatly depending on membrane type: e.g. inner mitochondrial and myelin sheath
Membrane lipids
wide diversity of amphiathic lipids. most are phosolipids. Cholesterol is also present. Are distributed asymmetrically n the outer and inner layer of the bilayer.
Membrane proteins
can be more than half of the membrane mass. structural and regulatory functionss. two main types are Integral proteins and peripheral proteins
Lipid types
Phospholipids, sphingolipids, glycolipids, cholesterol
Phospholipids
make up lipid bi-layer. primarily phosphoglycerides
Sphingolipids
alter electrical properties
Glycolipids
communication between cells
Cholesterol
increase fluidity while decreasing permeability
Selectivity of membrane lipids
easy passage of water and no passage of proteins, glucose, and amino acids.
Integral membrane proteins
Tightly bound to the membrane. Embedded in bilayer or spanning the entire membrane.
Peripheral membrane proteins
weaker association with the lipid bilayer
Semipermeable membrane
allows molecules to cross while restricting others
Osmosis
the diffusion of water
Osmotic pressure
force associated with the diffusion of water
Osmolarity
the ability of a solution to induce water to diffuse across a membrane. determined by the concentration of dissolved particles.
Tonicity
the effect of a solution on cell volume.
hyperosmotic
higher osmolarity
hyposmotic
a solution with a lower osmolarity
isosmotic
osmolarities are the same
water diffuses from a ____ solution to a ____ solution
hyposmotic to hyperosmotic
hypertonic solution
water leaves the cell by osmosis. cells shrink
hypotonic
water enters the cell by osmosis. cells swell.
Isotonic
no net osmosis. cell neither shrink nor swell
Mode of membrane transport
passive diffusion
Passive diffusion
lipid-soluble molecules. no specific transporters are needed - molecules cross lipid bilayer. no energy needed. depends on concentration gradient - from high to low concentration. steeper gradient results in faster results. Example: water, steroid hormones and common medicines.
Facilitated Diffusion
hydrophilic molecules. protein transporter is needed. no energy needed. depends on concentration gradient - from high concentration to low concentration. Example: glucose, ions, amino acids.
Active transport
Protein transporter is needed. energy is required. molecules can be moved from low to high concentration.
Types of facilitated diffusion:
carrier proteins for small organic molecules such as glucose. ion channels: Na+, K+,Ca2+, Cl-.
Ion channels
a) a gate controls the opening and closing of the channel. b) three types: voltage-gated, ligand-gated, and mechanogated ion channels. c) defective channels -> severe diseases (Example: cystic fibrosis).
Two types of active transport
primary and secondary
Primary active transport
direct use of an exergonic reaction: ATP hydrolysis. Example: Na+/K+ ATPase (pump): found in the plasma membranes of every cell; spends one ATP for transporting 3 Na+ ions out of and 2 K+ ions into the cell; results in high K+ and low Na+ in the cytoplasm; results in a voltage difference across the membrane (membrane potential).
Secondary active transport
Use energy in electrochemical gradient of one molecule to drive another molecule against its gradient.
Antiport or exchange carrier
molecules move in opposite directions. secondary active transport. Example: Cl-/HCO3- exchanger in red blood cells.
Symport or cotransporter
molecules move in the same direction. secondary active transport. Example: Na+ gradient is used to efficiently drive glucose or amino acid import.
First law of thermodynamics
energy can be neither created nor destroyed; total energy in the universe remains constant.
Second law of thermodynamics
Disorder (entropy) in the universe, a closed system, is continuously increasing. no energy transfer is 100% efficient. Some energy dissipates as heat, random motion that contributes to entropy.
Potential energy
stored energy
Kinetic energy
energy of motion
Free energy
as energy increases, free energy decreases. G=H-TS where G is free energy, H is enthalpy (potential energy of the system), T is temperature in Kelvin, and S is entropy.
Dynamic Equilibrium
in a chemical reaction. rate of change is exactly the same in both directions. no work is done. delta G = 0.
Exergonic reactions
has negative delta G value -free energy decreases. are spontaneous - release free energy that can perform work.
Endergonic reactions
have positive delta G value - free energy increases. are not spontaneous.
coupled reaction
input of free energy is required to drive an endergonic reaction is supplied by an exergonic reaction. ATP hydrolysis is used to drive most cellular endergonic processes.
Adenosine triphosphate (ATP)
immediate energy currency of cells. donates energy of 3rd phosphate group. formed by phosphorylation of adenosine diphosphate (ADP) - endergonic process.
Catabolism
degradation of large complex molecules into smaller, simpler molecules. exergonic
Anabolism
synthesis of complex molecules from simpler molecules. endergonic
Phosphocreatine
alternative high-energy phosphate compound. creatine + ATP ADP + phosphoceatine. Reaction is reversible so phosphocreatine can be used to produced ATP when levels are low.
Routine ATP synthesis involves a symphony of events including ___, ____, and ____.
glycolysis, the TCA (Krebs) cycle. and the oxidative phosphorylation.
Equation of Glycolysis
Glucose + 2 ADP + 2 Pi + 2NAD+ —-> 2 Pyruvate + 2 ATP + 2 NADH + 2 H+ + 2 H2O
Enzymes
are mediators of metabolism, responsible fro almost all of the reactions that occurs in a cell. required only in small amounts, have no effect of the delta G of the reaction. lower the activation energy. active and allosteric sites.
Metabolic rate
the rate of energy consumption. the rate which organisms convert chemical energy to heat and body work. the measurement is a basic indicator of important life processes and allows us to see effects of challenges to the animals, such as environmental changes, activity, sickness, drugs, etc.
Methods of measuring metabolic rate
a) direct calorimetry - measures the number of calories ingested by the animal. b) indirect calorimetry - measures the consumption of oxygen rather than dealing with calories.
Respiratory Quotient (RQ)
compares the volume of carbon dioxide produced to the volume of oxygen consumed by dividing the former by the latter. RQ = .7 for lipids, .8 for proteins, 1.0 for carbohydrates.
A ____ is necessary for metabolic rate
base line
Three items need consideration as to their effects of metabolic rate:
circadian rhythms, environmental fluctuations, physiological and genetic constitution of the animal, including its body mass.
Two ways to look at the effect of body size on metabolic rate
a) with increasing body size, the metabolic rate (O2 consumption) of the whole animal increases. b) with increasing body size, the metabolic rate per gram of animal decreases.
Competitive inhibition
the inhibitor competes with the normal substrate for the active site of the enzyme. a competetive inhibitor occupies the active site only temporarily.
Noncompetitive inhibition
the inhibitor binds with the enzyme at a site other than the active site, altering the shaoe of the enzyme and thereby inactivating it.
Multicellular organisms must ____ the activitie of the millions - trillions of cells that compose their bodies. This ____ requires that cells be able to communicate information to other cells, sometimes over great distances.
coordinate, coordination
Cell signaling
communication between cells
Types of cell signaling
direct (contact-dependent) signaling, autocrine and paracrine signaling, endocrine signaling, neuronal signaling.
Direct (contact-dependent) signaling
signaling cell and target cell connected by gap junctions. signal passed directly from one cell to another.
Indirect cell signaling
signalig cell releases chemical messenger. chemical messenger carried in extracellular fluid. Chemical messenger binds to a receptor on target cell. Activation of signaling transduction pathway. response in target cell.
Paracrine signaling
short distance indirect signaling. chemical messenger diffuses to nearby cell.
Autocrine signaling
short distance indirect signaling. chemical messenger diffuses back to signaling cell.
Endocrine signaling
long distance indirect signaling. chemical messenger tranported by circulatory system.
Nueronal signaling
long distance indirect signaling. electrical signal travels along a neuron and chemical messenger is released.
Types of chemical messengers (ligands)
peptides, steroids, biogenic amines, and nitric oxide (NO)
Gap junctions
specialized protein complexes create an aqueous pore between adjacent cells. movement of ions between cells, changes in membrane potential. chemical messengers can travel through (Example cAMP). Opening and closing can be regulated.
Peptide/ Protein Hormones
2-200 amino acids long. synthesized on the rough ER. stored in vesicles. secreted by exocytosis. hydrophilic (soluble in aqueous solutions). Bind to transmembrane receptors. Rapid effects on target cell.
Steroid Hormones
Derived from cholesterol. synthesized by smooth ER or mitochondria. three classes: mineralocoticoids (electrolyte balance), glucocorticoides (stress hormones), and reproductive hormones. hydrophobic. can diffuse through plasma membrane. cannot be stored in cell. must be synthesized on demand. transported to target ell by carrier proteins. slow effect on target cell (gene transcription).
Amine Hormones
Chemicals that posses amine group (-NH2). Some true hormones, some neurotransmitters, some both. Most hydrophylic (thyroid hormones are hydrophobic). Diverse effects.
Gases - NO - Chemical Messengers
most act as paracrines
Intracellular receptors
located inside of the cell and interact with hydrophobic chemical messengers.
Transmembrane receptors
are located in cell plasma membrane and generally interact with hydrophilic chemical messengers.
Types of transmembrane receptors
Ligand-gated ion channels, receptor-enzymes, G-protein-coupled receptors (GPCR)
Ligand-gated ion channels
initiate a response in the target cell by changing the ion permeability of the membrane. only the correctly shaped ligand can bind to the recptor.
Ligand mimics
Agonists- activate receptors. Antagonists- block receptors. many act as drugs or poisons.
Receptor-enzymes
induce a response by activating or inactivating intracellular enzymes.
G-protein-coupled receptors (GPCR)
send signals to an associated G protein, which then initiates a signal transduction pathway that causes a response in the target cell.
Detailed GPCR explanation
a) G proteins are describes as heterotrimeric because they have 3 different polypeptide subunits (aplha, beta, gamma). b) when ligand binds to the GPCR on the surface of cells, the receptor is activated. c) activated receptor binds to G-protein-GDP. d) GDP is replaced by GTP. G-protein-GDP becomes G-protein-GTP. e) G-protein-GTP disassociates, G subunit alpha-GTP activated adenylyl cyclase (AC). f) Activated AC uses ATP to make cAMP. g) GTP of G subunit alpha-GTP hydrolyzes to form G subunit alpha-GDP. G subunit alpha-GDP disassociates from AC and reassociates with betagamma units to reform the inactive heterotrimeric G protein.
Hypothalamus
1) integral to communication between nervous and endocrine systems. 2) produces hormones that act on pituitary gland.
Pituitary glands have two portions
anterior and posterior
Anterior pituitary
makes and secretes growth hormone, thyroid stimulating hormone, prolactin, follicle stimating hormone, luteinizing hormone, and adrenocorticotropic hormone.
Posterior pituitary
does not synthesize hormones; it releases two hormones that are made in hypothalamus: oxytocin, antidiuretic hormone.
ADH
acts to reduce urine production. goal is to retain more water.
ADH release process
Osmoreceptors are located in the hypothalamus. they are sensitive to blood osmotic pressure. elevated osmotic pressure (low blood volume) triggers release of ADH. When ADH travels and reaches target cells (Kidney, frog’s skin), it binds to the receptor located in target cell. This turnes on G-protein coupled receptor signaling pathway.
Movement is characteristic of animals. Movement is a cellular phenomenon that is dependent on the ____ and ____ that interact to form _____
cytoskeleton and motor proteins interact to form molecular motors.
cells can use a ____ as an intracellular support, using reorganization of the _____ elements to change cell shape.
cytoskeleton.
Cells use the ____ like a lever, pulling the cytoskeletoon backward.
motor protein
cells can use the ______ as a track for motor proteins to move along, often carrying intracellular cargo.
cytoskeleton
____ pull on the cytoskeleton, the cytoskeleton reorganizes and this generates movement.
Motor proteins
Cytoskeleton
protein-based intracellular network
motor proteins
enzymes that use energy from ATP to move
Microtubules (MTs)
made of polymerized alpha and beta tubulin heterodiemers: (-) and (+) ends. Two motor proteins: kinesins and dyneins move along MTs.
Kinesin
responsible for anterograde movement (to the + end of the microtubules)
Dynein
move in a direction opposie to kinesin (to the - end of microtubules)
Cilia
numerous wave-like motion. constructed of a precise arrangement of microtubules.
Flagella
single or in pairs, whiplike movement. constructed ofa precise arrangement of microtubules.
Microfilaments
made of the polymerization of globular actin subunits.
___ use actin polymerization during fertilization
sperm.
The motor protein, ____ moves along microfilaments
myosin
Actin and myosin based movement can be described as the _____ model
sliding filament
sliding filament model
Actin is the rope, myosin is your arm. Alternating cycle of grasp, pull, release. ATP binds causing myosin to detach. Myosin head extends and attaches to adjacent actin. Release of phosphate promotes power stroke. ADP is released.
the ability of muscle to generate motion is often related to the ____ system. muscle contraction is transmitted to a mechanical system by an ______ or ______
skeletal, endoskeleton, exoskeleton
exoskeleton
non-living skeleton (think cicada)
endoskeleton
consists of living tissue
skeletal system
supports and protects the body. transmits mechanical forces generated by muscles.
hydraulic skeleton
fluid in closed body compartment transmits forces generated by contractile cells or muscle. Found in soft-bodied invertebrates.
Two types of muscle cells
smooth and striated
Smooth muscle fibers
lack cross-striations, are spindle-shaped, and have centrally located nucleus. they occur generally in flat sheets rather than in discrete bundles. the cells are very close to one another, an important point for electrical connection between the cells. Connected at gap junctions, contract in all dimensions, no sarcomeres, no t-tubules and minimal SR.
Multiunit smooth muscle
Examples: iris, ciliary body, nictitating membrane, some muscle in blood vessels. Contraction cycles are short and they resemble skeletal muscle.
Visceral smooth muscle
The more typical smooth muscle. it features slower contraction and relaxation, often contracting spontaneously, often lining a cavity and exerting pressure on the contents of that cavity.
____ is involuntary and is innverted by both sympathetic and parasympathetic nerves usually that act antagonistically.
Smooth Muscle
Smooth muscle contains ____, ____, and ___ but these proteins are less highly organized structurally than they are in skeletal and cardiac muscle. The sliding filament process probably applies in smooth muscle contraction.
actin, myosin, and tropomyosin
Understanding that categorizing muscle types is somewhat imprecise, skeletal muscle is sometimes identified in at least two categories:
type I fibers and type II fibers.
Type I fibers
tonic fibers; largely aerobic yeilding relatively slow contractions that are sustained; recieve multiple innervations and a fiber responds by a summation of small contractions.
Type II fibers
twitch fibers; largely anaerobic during contraction; no graded response (that is, there is “all-or-none” contraction by an individual cell); there are other subdivisions of this category. This is the type of skeletal muscle more common in vertebrates.
Specialized terminology associated with a muscle discussion
sarcolemma, sarcoplasm, sarcoplasm recticulum, sarcosomes.
Myocytes
muscle cells. contractile unique to animals
each skeletal muscle fiber is composed of parallel ____.
myofibrils
Myofibrils are composed of ____ and _____ filaments.
myosin (thick) and actin (thin)
The region of a sarcomere where thick filaments occur forms a dark region called the _____. It is the middle region of the sarcomere.
A (anisotropic) band
The ____ appears lighter because there is no myosin there. It is located on either side of Z disk and occupied by thin filament
I (Isotropic) band
The ____ (with an M line in the middle) appears lighter because there is no actin there.
H zone
Z disks
form border of the sarcomere. Thin filaments attached to it extend from it towards the middle of sarcomere.
sarcomeres are arranged into _____ - single, linear continuous stretch of interconnected sarcomeres. Extends the length of the muscle cell. have a parallel arrangement in the cell.
myofibrils
During contraction we see this happen
a) the H zone becomes smaller or disappears. b) the A bands stay the same size. c) the I bands become smaller. d) the z lines get closer.
“triad” in skeletal muscle
At various places the sarcolemma invaginates into the fiber and this membrane now comes in close contact with two pieces of the sarcoplasmic recticulum forming a “triad” of membranes. This is an important anatomic item in that it carries the muscle fiber action potential (impulse) into the interior of the cell.
Sarcoplamic recticulum
Stores Ca2+ bound to protein sequestrin. Terminal cisternae increase storage.
Transverse tubules (t-tubules)
Invaginations of sarolemma. Enhance penetration of action potential into myocyte.More developed in larger, faster twitching muscles. Less developed in cardiac muscle.
Regulation of contraction
exitation-contracting coupling. depolarization of the muscle plasma membrane. Elevation of intracellular Ca2+. contraction - sliding filaments.
Ca2+ allows myosin to bind to actin
At rest, cytoplasmic Ca2+ is low. Troponin-tropomyosin cover myosin binding sites on actin. Cytoplasmic Ca2+ increases. Ca2+ binds to TnC. Troponin-tropomyosin moves, exposing myosin-binding site on actin. Myosin binds to actin and cross-bridge cycle begins. Cycles continue as long as Ca2+ is present. Cell relaxes when sarcolemma repolarizes and intracellular Ca2+ returns to resting levels.
isometric contraction
one in which the length of the fiber stays the same but the internal tension increases.
isotonic contraction
one in which the length changes (shortens) but the tension stays the same.
Recording of a single twitch of a muscle, though artificial from a normal standpoint, shows some important contraction characteristics. Those include the ___, ____, and ____
latent period, contraction period, and the relaxation period.
Applying repeated stimulations befor relaxation can occur causes the contractions to pile on top of one another. This is also called ____.
Temporal summation.
The starling principle
illustrates that, up to a point, pre-stretch/pre-loading of muscle yields a more forceful contraction.
____ represent lose anatomic associations between cells and contribute to the functional syncytial nature of cardiac muscle.
Intercalated discs
Noteable features of cardiac muscle
a) starling principle. b) the lack of a stable resting potential leading to spontaneous contractions. c) extended action potentials. d) a clear refractory period..
an organism’s ability to survive and to maintain homeostasis depends largely on how effectively it detects and responds to ___ - changes in the environment. Most animals have a nervous system that, like a cmputer, takes in information, integrates it, and responds.
stimuli
The nervouse system is composed mainly of two specialized types of cells __ and ___.
neurons and glial cells
A typical neuron consists of
a cell body, dendrites, and an axon.
In vertebrates, the axons of many neurons outside the central nervous system are surrounded by ___, glial cells that form an insulating covering called the myelin sheath.
Schwann cells
___ is a whit, fatty material found in the plasma membranes of Schwann cells.
Myelin
The _____ in a neuron is basically the same as the ___ in a muscle fiber. both are “excitable” cells.
electrical event
Depolarization
membrane potential becomes less negative
Repolarization
membrane potential returns to resting value
Hyperpolarization
membrane potential becomes more negative than resting value.
To account for the resting potential difference, we note the ___ and ___ and certain underlying membrane
intracellular and extracellular fluid ionic components
The resting potential features these ionic characteristics:
in the intracellular fluid, K+ is the principle cation, there is some Na+, and the chief anion is mostly protein. In the extracellular fluid Na+ is the principle cation, there is some K+, and the chief anion is Cl-.
Important characteristics underlying the resting potential include these items:
The membrane is impermeable to protein. In the resting neuron, the membrane is up to 100 times as permeable to K+ as to Na+. Na+ pumped out of the neuron cannot easily pass back into the cell, but K+ pumped into the neuron easily diffuse out. Therefore, the resting potential has been identified as K+ diffusion potential.
Action potential
is a reversed polarity across the membrane. the neuron becomes more permeable to sodium ions. theres is also an increase in permeability to potassium ions that follows the sodium ion permeability increase. Therefore, it has been identified as a sodium ion diffusion potential.
Threshold
represents the amount of disturbance that a resting potential can absorb before an action potential is generated.
All or none responses
occurs or doesn’t occur all APs are same magnitude
Absolute refractory period
coincides with the depolarization and repolarization phases. cell incapable of generating a new AP
Relative refractory period
coincides with the after-hyperpolarization phase. more difficult to generate new AP
Spatial summation
graded potentials from different sites influence the net change
Temporal summation
graded potentials that occur at slightly different times influence net change.
Synapse
a junction between a neuron and another neuorn or effector cell. consists of a presynaptic, the synaptic cleft, and a postsynaptic cell.
neuromuscular junction
a specific type of synapse involving the terminal part of a motor axon and the sarcolemma of a nearby muscle fiber. At this junction, a neurotransmitter substance is released from the axon. it travels across the synapse and contacts the sarcolemma and acts as a stimulus. this is an example of a ligand-gated event. subsequent propagation of the action potential down the sarcolemma occurs by voltage-gated events.
Electronic current spread
charge spreads along membrane
regenerative cycle
ion entry -> electronic current spread -> triggering of AP
self propagating
an AP triggers the next AP in adjacent areas of the membrane without degradation.
____ conductance of action potentials is common in animals. In a few specialized situations, there is also __ conductance of action potentials. In these situations, the cell membranes of the adjacent cells are close enough that an action potential can be passed electrically from one to another via ion flow. These are typically bi-directional, in contrast to more typical chemical synapses that are one-way
chemical, electrical
neurotransmitters
synthesized in neurons; released by presynaptic cell following depolarization; bind to postsynaptic receptor and cause an effect
Acetylcholine (ACh)
causes post synaptic potential that is stimulatory to the skeletal muscle.
Inhibitory neurotransmitters
cause hyperpolarization of the membrane - inhibitory postsynaptic potential (IPSP). Make postsynaptic cell less likely to generate an AP.
Excitatory neurotransmitters
cause depolarization of membrane- excitatory postsynaptic potential (EPSP). make postsynaptic cell more likely to generate an AP.
At any synapse the transmitter substance present must be ____.
Temporary.
At the neuromuscular junction, ACh cannot just stay in the synaptic cleft; it is broken down by ____ in the synaptic space. This allows the receiver cell membrane to return to resting potential.
acetylcholine esterase (AChE)
Organophosphate (OP)
insecticides that inhibit AChE activities. widely used to control insect pests.
Two experimental manipulations allow us further insight into the neuromuscular junction.
a) compounds such as curare that stabilizes the sarcolemma. b)compounds such as nicotine and succinylcholine chloride that lead to persistent depolarization.
____ are often classified as either ionotropic or metabotropic.
Neurotransmitter receptors
Ionotropic receptors
are ligand-gated ion channels. Fast
Metabotropic receptors
receptor changes shape. formation of second messenger. alters opening of ion channel. slow. may lead to long-term changes via other cellular functions.
ACh receptors can be ____ or ___
ionotropic or metabotropic
Two major classes of ACh receptors
the nicotinic and the mscarinic receptors.
Receptor for ____ and _____ are termed the adrenergic receptors. In mammals, the great diversity of receptors ( alpha 1, alpha 2, beta 1, beta 2, etc) allows ___ and ____ to have opposing effects on different tissues, depending on the particular receptor that is present.
norepinephrine and epinephrine
___ detect information about changes in the internal or external environment. They can be as simple as a single sensory neuron, or can involve complex sense organs, such as eyes, ears, and nose.
sensory receptors
____ refer to cells that are specialized to detect incoming sensory stimuli. some ___ are themselves afferent neurons. Other ____ are epithelial cells that send a signal to a separate afferent neuron.
sensory receptors
Based on the type of stimulus, there are
chemoreceptors, mechanoreceptors, photoreceptors, thermoreceptors, electroreceptors, and magnetoreceptors
generator potential
sensory receptor is also the primary afferent neuron. change in membrane potential spreads along membrane.
receptor potential
sensory receptor is separate from the afferent neuron. change in membrane potential triggers release of neurotransmitter.
Most cells can sense incoming ___, and animals have many types of _____ that they use to sense their external and internal chemical environments, such as olfaction and gustation.
chemical signals, chemoreceptors
__ are neurons with cilia. __ are G-protein-coupled receptors
olfactory receptor cells, odorant receptor proteins.
Odorant receptors
a)binding of odorant to an ororant receptor protein causes a conformation change, which sends a signal to an associated G-protein, Golf. b) activated Golf activates adenylate cyclase (AC). c) Activated AC uses ATP to make cAMP. d) cAMP opens cAMP-gated Na+ and Ca2+ channels. e) Na+ and Ca2+ enter the cell, causing a generator potential. f) the Ca2+ also opens Ca2+ activated Cl- channels, causing Cl- to leave the cell, increasing depolarization. g) the generator potential opens voltage-gated Na+ channels, triggering action potentials.
Taste receptors are ____ that release neurotransmitters
epithelial cells
Taste Receptor cells
a) Na+ from salty food enters through a Na+ channel, causing a recptor potential. b) the resulting depolarization opens voltage gated Ca2+ channels. c) the influx of causes neurotransmitter release. d) the releasing of neurotransmitter would trigger an action potential in the afferent neuron.
____consists of the entire field that can be seen without moving the eyes. In humans, about half of the neurons coming from each eye cross over each other in the optic chiasm
Visual field
The ___ is one of the body’s homeostatic control systems, helping to regulate physiological processes and coordinate behavior.
nervous system
Associated with the nervous system
afferent neurons, efferent neurons, and interneurons. Central nervous system and peripheral nervous system.
In vertebrates, ___ is composed of the brain and spinal cord. The___ is protected by the meninges.
Central nervous system (CNS)
The ____ are made of one or more protective layers of connective tissues.
meninges
Within the meninges, the brain and spinal cord float in a plasma-like fluid called
cerebrospinal fluid (CSF)
The CNS is also physiologically separated from the rest of the body by the ____, which is formed by tight junctions between the endothelial cells lining the brain capillaries.
blood-brain barrier
The _____ prevents materials from leaking out of the bloodstream and into the CNS via paracellular patways
blood-brain barrier
The efferent branch of the PNS can be divided into two main divisions:
the autonomic division and the somatic motor division
Autonomic nervous system
is involved in the homeostatic regulation of most physiological function, including heart rate, blood pressure, breathing, and many other processes that are critical for life.
Somatic motor pathways
control skeletal muscles, which are usually under conscious control
The autonomic division can be differentiated into three branches
the sympathetic, parasympathetic, and enteric nervous systems.
Sympathetic nervous system
is most active during periods of stress or physical activity, and is referred as “fight or flight” system.
Parasympathetic nervous system
is most active during periods of rest, and is referred as “resting and digesting” system.
Enteric system
is mainly involed in digestion.
The CNS regulates the _____
autonomic nervous system
three mechanisms for regulating autonomic function
dual innervation, antagonistic action, basal tone
dual innervation
most organs recieve input from both systems
antagonistic action
one system stimulates while other inhibits
basal tone
even under resting conditions autonomic neurons carry APs
three parts of the meninges
dura mater, arachnoid mater, pia mater
spinal nerves
branch from spinal cord. enter and exit between adjacent vertebrae. named based on region of vertebral column from which they emerge. mixed nerves.
Cranial nerves
exit directly from skull. 13 pairs. some afferent, some efferent, some mixed.
