Exam 1: Cell Physiology & Neurophysiology Flashcards
Define physiology
The study of how living organisms function and work, the WHY and HOW
Looks at mechanisms underlying integrated events at the level of molecules, cells, tissues, organs, and organ tissues
Employs approaches of integrative science
Explain the body control mechanism and the closed loop
Variable - what is being regulated
Sensor (receptor) - detects changes in the variable
Integrating center (controller, command center) - makes the decision
Effector - makes the change in the variable
What is homeostatic negative feedback, and explain the role of the control elements
A closed loop that keeps a variable toward the set point
Response to a change in a variable that moves the variable in the opposite direction
Ex: The body’s desired temp is 37 C, when body exceeds it is picked up by nerve cells in skin and brain, temp regulatory center in brain, sweat glands throughout body, body temp is lowered
Ex: Blood glucose rises after a meal, which is sensed, then to integrating center, to effector, to lowering glucose
What is non-homeostatic positive feedback, and explain the role of the control elements
Non-homeostatic, explosive and amplified responses in the same direction to a change in the variable,
Good for activating systems rapidly
Requires exit stop
Often leads to pathological conditions
Ex: Blood clotting, uterine contractions, opening of voltage-gated channels
What is dynamic internal consistency
Levels of a variable can change over short periods of time, but will remain relatively constant over long periods of time
What happens if negative feedback for blood glucose concentration fails
Diabetes Mellitus (morbidity and mortality), hyperglycemia
What if negative feedback in maintaining core body temp fails
Hyperthermia - body temp set point remains the same and the elevated body temp is too high for the set point and heat loss is needed, if fails, heat exhaustion -> heat stroke
Explain blood clotting in terms of non-homeostatic positive feedback
Explain Uterine contraction in terms of non-homeostatic positive feedback
Explain voltage-gated channels leading to action potential in terms of non-homeostatic positive feedback
What are stem cells
“Undeclared” cells and can duplicate/change into many different cells
What are totipotent cells
(2-8 cell stage) can develop into a person in utero and have the ability to make an embryo and extra-embryonic cells that make a placenta
What are pluripotent cells
(Inner cell mass of a blastocyst) can develop into any cell type of the body
What are multipotent cells
(hematopoietic stem cells) can develop into a limited number of cells with the same lineage
ectoderm cells, mesoderm cells, endoderm cells
Explain ectoderm cells, mesoderm cells, and endoderm cells
Ectoderm: neurons, glial cells, odontoblasts, epidermis, retina/lens, pigment cells
Mesoderm: Connective tissue, skeletal muscles, smooth muscles, urogenital system, adipose tissue, blood cells
Endoderm: Pulmonary alveoli, thyroid gland, pancreatic cells, intestinal epithelium
What are the 4 basic types of the oral cavity cells
Nerve cell, muscle cell, epithelial cell, connective cell
Name the matrix amount, matrix type, unique features and location of epithelial cells
Matrix amount: Minimal
Matrix type: Basement membrane
Unique features: No direct blood supply
Location: Covers body surface, lines cavities and hollow organs and tubes, Secretory glands
Name the matrix amount, matrix type, unique features and location of connective cells
Matrix amount: Extensive
Matrix type: Varies; protein fibers in ground substance that ranges from liquid to gelatinous to firm to calcified
Unique features: Cartilage has no blood supply
Location: Supports skin and other organs; Cartilage, bone and blood
Name the matrix amount, matrix type, unique features and location of muscle cells
Matrix amount: Absent
Matrix type: NA
Unique features: Able to generate electrical signals, force, and movement
Location: Makes up skeletal muscles, hollow organs, tubes, cardiac muscle, smooth and skeletal muscle
Name the matrix amount, matrix type, unique features and location of nerve cells
Matrix amount: Absent
Matrix type: NA
Unique features: Able to generate electrical signals
Location: Throughout body, concentrated in brain and spinal cord
Name the organization of the body
Cell, tissue, organ, organ system
What is a cell
Smallest unit; basic unit of the body - 100 trillion of cells - all work together
What is a tissue
Group of the same cells
What is an organ
Consisted of multiple tissues that work together to perform specific function
What is an organ system
Consisted of multiple organs that work together for a specific job
i.e. cardiovascular system
What functions of the organ system are controlled at a cellular level
Growth, healing, repair, hypertrophy, hyperplasia, atrophy, metaplasia, dysplasia, tumor
Name cellular organelles that control the functions of the organ systems
Nucleus, ribosome, endoplasmic reticulum, golgi apparatus, lysosome and peroxisome, cytoskeleton, plasma membrane
Describe the nucleus and what it does
Site of DNA replication and transcription and RNA processing
Surrounded by nuclear envelope: Nuclear pores join the 2 membranes of the nuclear envelope together
Nucleoli: contains genes for forming RNA associated with ribosomes
Chromatin: DNA and histone proteins
Explain DNA replication in the nucleus
Explain transcription and RNA processing in the nucleus
What are ribosomes and what do they do
Free ones function in the cytosol
Membrane bound ribosomes (rough ER) synthesize proteins that are bound for organelles in the ER, golgi apparatus, lysosomes, or plasma membrane : some proteins are sent to secretory vesicles and later expelled from the cell via exocytosis
Describe the endoplasmic reticulum
Rough - with ribosomes, site of protein synthesis (membrane-proteins and secretory proteins)
Smooth - site of lipid/steroid synthesis and calcium storage (no ribosomes)
Calcium stored in sarcoplasmic reticulum
Explain the golgi apparatus
Site of modification, packaging, and trafficking of secretory protein or membrane proteins
Explain the mitochondria
Site of ATP synthesis (powerhouse of cell)
Cellular respiration (oxidation of glucose derivatives, fatty acids and amino acids)
Site of electron transport system that generates ATP molecules
Lipid and steroid synthesis along with smooth ER
Explain lysosomes and peroxisomes
Cellular sorting center for cellular disposal debris and toxins
Lysosomes: digestive enzymes, digest macromolecules and damaged cell organelles (autophagy)
Peroxisomes: hydrogen peroxide, modifies of fatty acids and phospholipids, alcohol and toxins, detoxification center
Explain the cytoskeleton
Movement of organelles and shape/movement of a cell
Microfilament: Actin, gliding, contraction and cytokinesis
Intermediate filament: Keratin gives strength
Microtubule: Tubulin acts as a scaffold to determine cell shape and movement of cell organelles and vesicles, spindle fibers, flagella, cilia
Explain plasma membrane
cell boundary and transcellular movement of solutes and solvents
ECF = ISF + Plasma
Phospholipid bilayer + proteins
Components of plasma membrane
Phospholipid bilayer + proteins
Lipids: repel water but passes small hydrophobic molecules such as gases and steroids
Amphipathic phospholipids form a bilayer, fatty acid tail increase fluidity
Cholesterol: Amphipathic molecule, decrease membrane mobility at 37C
Explain the proteins of the plasma membrane
Integral membrane proteins: proteins that are embedded in the lipid bilayer
Peripheral proteins: proteins that are NOT embedded in the bilayer, reside at one surface, bound to integral proteins, cytoskeletons, signaling molecules
Carbohydrates in proteins and lipids of the membrane modify their functions
Summary of cell organelles and their functions
Explain interdependent relationship of cells, body systems and homeostasis
Explain movement with plasma membrane
Average ion concentration in blood plasma, ISF, and ICF
Explain osmosis (movement of solvent/water)
Passive movement of water by diffusion: No energy required
In order for it to occur: Must be difference in solute concentration across the membrane
Membrane must be selectively permeable to water but not the solute
Define characteristics of diffusion
High concentration to low concentration
No energy required
rate is higher for:Larger concentration gradient of the solute, higher temp of the environment, larger surface area of the membrane
rate of diffusion = permeability x area x [C1-C2]
Explain passive transport of small hydrophobic molecules (uncharged, non-polar) by diffusion
High permeability
Down the concentration gradient (high -> low)
permeability matters
i.e. gases, hydrophobic hormones such as steroid hormones and thyroid hormones because they are small enough to pass through
Explain passive transport of hydrophilic (charged) ions
Pass through integral proteins that form a channel
down the concentration gradient (high -> low)
permeability is determined by selectivity
i.e. ions such as Na+, K+, Ca++, etc
Explain ion channels, leaky and gated
Leaky - always open
Gated - voltage, ligand, signal-gated
Explain the movement of large polar substances
Require carriers
move by facilitated diffusion (no energy)
down the concentration gradient (high -> low)
i.e. glucose by glucose transporter
They are integral proteins and transport has these characteristics:
- specificity
- competition
- saturation (Tm)
Explain active movement
Requires a carrier and energy expenditure
Moving substances AGAINST their concentration gradient (low -> high)
Primary and secondary
Explain primary active transporters
Enzymes that hydrolyze ATP
Using their energy released form ATP hydrolysis, they move molecules against the concentration gradient (low-> high)
Explain secondary active transporters
Symporters or antiporters
“Hitching a ride”
Na-K pumps Na out of the cell, Na low inside now, When Na moves back into the cell, other substances, are transported by the same carrier proteins (i.e. glucose)
Uptake of amino acids at the apical membrane requires secondary active transporter, amino-acid Na symporter which requires the Na-K pump activity
In the presence of the solute concentration gradient (1 Osm glucose in the left vs. 2 Osm in the right), water will _______ across the membrane
Move from low(solute) to high (solute) across the membrane
Explain endocytosis
Extracellular -> intracellular
Phagocytosis (engulfing bacteria)
Pinocytosis (interstitial fluid)
Receptor-mediated endocytosis (LDL uptake)
Give a summary of the molecular movement through the plasma membrane
What is resting membrane potential
Membrane potential of the inside of the cell (-90 to -65 mV) compared to the outside of the cell (0 mV) at rest
K permeability os greater than Na permeability
Intracellular K and Na remain relatively constant due to Na/K pump
What is depolarization
Membrane potential becomes less negative, inside of cell becomes more positive with respect to RMP
Membrane permeability to Na (and or Ca++) increases
Action potentials
What is repolarization
a return to the resting membrane potential
What is hyperpolariation
membrane potential becomes more negative, inside the cell becomes more negative with respect to the RMP
Explain passive and voltage gated ion channels
Passive: ion channels that are always open and allow ions to move down their concentration and electrical gradients (usually selective to K) ;Sometimes called leaky channels
Voltage gated channels: open or close when they detect a change in the membrane potential. Open, and then inactive when the membrane depolarizes. Close when the membrane repolarizes
What are chemically gated ion channels
Also called ligand gated channels - open when a chemical ligand (neurotransmitter) binds the channel
Chemical ligands can bind from the cytosol or extracellular fluid
Name how much millimoles there are of blood plasma, ISF and ICF for Na, K, Ca, and Cl
Explain how Na/K pump keeps gradients constant
Pumps Na and K in opposite directions
“electrogenic”- pumps 3 Na out for every 2 K in
Maintains low Na concentration and high K concentration in the cells
Explain how action potentials work in neurons
Explain how membrane permeability changes during an AP
AP depolarization is produced by an increase in Na+ permeability, after short delay, repolarization occurs due to increase in K+ permeability
Action potentials in different cell types
Explain neuron excitability
Dendrites receive incoming signal (graded potential)
Graded potential travels to a trigger zone
axon hillock: site where AP originates when incoming signal reaches threshold
What are graded potentials
Amplitude of graded potentials depends on the strength of stimulus
They decrease in strength as they move through the cell/cytoplasm
If below threshold at trigger zone, then no AP occurs
threshold depolarizes the membrane to open VG Na+ channels in trigger zone to generate an AP
Temporal summation
two sub-threshold excitatory potentials will summate if they arrive in the trigger zone within a short period of time
No temporal summation
Spatial summation
3 separate neurons can generate subthreshold excitatory graded potentials (excitatory postsynaptic potential EPSP)
Can summate in trigger zone to generate AP
Explain spacial summation in terms of inhibitory signals
excitatory postsynaptic potential = depolarization
Inhibitory postsynaptic potential (IPSP) repolarization or hyperpolarization, damp or prevent EPSP from reaching threshold
Explain integration
Explain divergence integration
Explain convergence integration
Explain VG Na+ channels in the trigger zone
Membrane depolarization causes Na+ channels to open, which depolarizes the membrane more, causing more VG Na+ channels to open -> AP
Example of positive feedback!!
AP refractoriness: Absolute vs relative
Absolute - membrane in incapable of producing another AP, VG Na+ channels are open or inactivated
Relative - Axon membrane can produce another AP, but requires stringer stimulus because VG K+ channels are open, making it harder to depolarize
AP conduction
Influx of Na+ depolarizes the adjacent region membrane, shooting AP down the axon
AP must be produced at every part of the axon
Occurs in 1 direction and previous region is in it refractory period
How mylinated axon increase speed of AP conduction
Myelin prevents decay of AP signal (insulation)
Spaces between myelin (Nodes of ranvier) contain VG Na+ and K+ channels
AP only occurs at the nodes (AP at 1 node depolarizes membrane to reach threshold at the next node)
Saltatory conduction (leaps) - fast rate of conduction; jumping from node to node
Disease states can decrease myelination and disrupt AP conduction
Electrical synapse
Electrical - gap junctions (intercellular channels) allow direct ionic current flow between cells
Impulses can be regenerated without interruption in adjacent cells
the gap junctions connect cytoplasm of 2 cells because adjacent cells are electrically coupled
brain (rare), smooth and cardiac muscles, glial cells
Chemical synapse
Uses neurotransmitters released from presynaptic neuron that bind to receptor proteins on postsynaptic cell to alter its membrane potential
Presynaptic axon terminal is separated from post synaptic cell by synaptic cleft
Chemical ligands are released form pre-synap in synaptic vesicle
vesicles fuse with axon membrane and the chemical ligands are released by exocytosis
Amount of chemical ligands released depends upon frequency of AP being generated
chemical ligands are released and diffuse across synaptic cleft
ligands bind to specific receptor proteins in post synaptic cell membrane
chemical ligands are cleared to end transmision
Post synaptic signalling
Iontropic receptors - chemically gated ion channels
Metabotropic receptors - indirectly linked with ion channels of the plasma membrane of the cell through intracellular signal transduction mechanisms (seconds messenger, often G-protein coupled receptors)
Gap junctions
intercellular channels that allow direct ionic current flow between cells
Organization of nervous system
PNS - cranial and spinal nerves
Afferent - in to CNS
Efferent - out of CNS
Functional classification of nerves
Sensory (afferent) - impulses from sensory receptors to CNS
Interneurons (CNS) - integrative function
Motor (efferent) - conduct impulses out of CNS to effector organs
Different types of neurons (Pseudounipolar, bipolar, multipolar)
Other glial cells in nervous system
Peripheral - schwann cells and satelite cells
CNS - astrocytes, microglia, oligodendrocytes, ependymal cells
Schwann cells and satellite cells
schwann cell - wrap around axon to form myelination in PNS, provide insulation and speed AP conduction
satellite cells - support neuron cell bodies within a group of neurons called ganglia
Oligodendrocytes
CNS; for a myelin sheath around axons of CNS
Similar to Schwann cells, but this is one cell forming many myelinations
Explain generator potentials, tonic response, and phasic response
Properties of stimulus intensity and sensory adaptation
Sensory adaptation:
- Tonic receptors: fire APs as long as stimulus is applied (pain)
- Phasic receptors: bursts of APs but quickly reduce firing rate even id stimulus maintained
What comprises the CN and difference between grey and white matter
CNS -> Brain and spinal cord
Grey = cell bodies, dendrites, synapse
White = axons connecting different parts of grey matter
Somatic motor pathway linking CNS to skeletal muscle (include ligand and receptors)
Each somatic neuron innervates a skeletal muscle cell and the motor neuron axon branches to innervate multiple fibers. Each muscle fiber receives a single axon terminal from its motor neuron
Ligand - ACh
Receptor - Nicotinic
Cellular pathway for both parasympathetic and sympathetic neurons linking the CNS to the target tissue (include ligand and receptor)
Parasympathetic has long pre ganglion and short post ganglion
- ACh and nicotinic
- ACh and muscarinic
Sympathetic has short pre ganglion and long post ganglion
- ACh nicotinic
- NorEpi adrenergic (alpha and beta)
- adrenergic is metabatropic (G-protein coupled) *
Autonomic signaling via the adrenal medulla
The properties of how the sympathetic system regulates blood vessel “tone”
Alpha receptors constrict blood vessels in most of body
Beta receptors dilate blood vessels that supply skeletal muscle
The steps associated with ligand release from varicosities. How is it similar or different than synaptic signaling with axon terminals
- Action potential arrives at the varicosity
- Depolarization opens voltage-gated Ca++ channels
- Ca++ entry triggers exocytosis of synaptic vesicles
- NE binds to adrenergic receptor to target
- Receptor activation ceases when NE diffuses away from synapse
