Exam 1 Flashcards
What is physiology?
The study of the functioning of living organisms
Define teleological and give an example.
Why something happens or the ultimate consequence it provides. Ex: Heart rate increases during exercise to increase blood flow to working muscles.
Define mechanistic and give an example.
How something happens. A heart rate increases during exercise because the sympathetic nervous system input increase to pacemaker cells of the heart.
What are the 4 themes of physiology?
- Structure & Function
- Biological Energy Use
- Infomation Flow
- Homeostasis
What is homeostasis?
The ability of the body to maintain a relatively constant internal environment.
What are examples of regulated variables?
Temperature, pH, ion concentrations, nutrient availability, etc.
What are the parts of a control system that maintains homeostasis?
Stimulus, Sensor, Integrating center, Target/Effector
What is the feedforward control strategy?
Occurs in anticipation of change
What is the feedback control strategy and what types are there?
Feedback occurs in response to change. Negative feedback restores normal value and positive feedback enhances change.
What is homeostatic dysregulation?
Body can’t maintain homeostasis which can lead to dysfunction, disease, and death.
What are the 3 types of biological work? Describe each.
- Chemical: Making/breaking chemical bonds
- Mechanical: moves things
- Transport: moves things across membrane of cell or organelle
What are the types of potential energy?
Chemical bonds, concentration gradients, and electrical gradients
What are the body’s 3 fluid comartments?
- Intracellular fluid (ICF)
Extracellular fluid (ECF) - Plasma (blood)
- Interstitial Fluid (ISF)
Compartments maintain _________ concentrations of each solute.
Different
What separates the ECF from ICF? Is it permeable to all substances.
Plasma membrane separates the ECF from ICF and is selectively permeable.
Define Lipophilic.
Hydrophobic (non-polar- no separation of charges)
Define Lipophobic.
Hydrophilic (polar)
What is a passive gradient?
Flowing down the concentration, from high concentration to low. Doesn’t require any energy to occur.
What is an active gradient?
Flowing against a gradient, from low to high. Uses ATP.
What are the 3 types of transport mechanisms? Describe each and what molecules they transport.
- Simple Diffusion: diffusion across lipid bilayer (nonpolar molecules: gases, lipids, etc)
- Protein-mediated transport: (small polar molecules: glucose, amino acids, water)
- Vesicular transport: (very large molecules: proteins)
What is Fick’s Law?
Diffusion rate is increased by:
-incr. surface area
-incr. concentration gradient
-incr. membrane permeability
-decr. diffusion distance
What is a channel protein? What do they transport?
Channel proteins form continuous connection between ICF & ECF to transport ions and water.
What are the types of channel proteins?
- Leakage (open)
- Gated (closed)
- Chemically-gated
- Mechanically- gated
- Voltage- gated
What are the characteristics of channel proteins?
-can only mediate passive transport
-rate depends on gradient & number of channels
What is a carrier protein?
Bind to molecules and change shape to carry them across a membrane.
What are the characteristics of carrier proteins?
-Never form continuous connection between ICF & ECF (“revolving door”)
-slower than channel proteins
-can move larger molecules
-can use passive or active transport to move across gradients
-has binding sites for transported molecules that displays specificity, competition, & saturation
What are the types of carrier proteins?
- Uniporter: one kind of molecule
- Cotransporter: two or more kinds of molecules
- Symporter: in same direction
- Antiporter: in opposite direction (exchanger)
What is primary active transport? What is an example?
Binds ATP directly. Ex: Na/K ATPase
What is secondary active transport? What is an example?
Uses ATP indirectly. Uses energy stored in a concentration gradient to move something else against its concentration gradient. Ex: Na/glucose-linked transporter
What are the characteristics of vesicular transport?
-for large molecules
-uses ATP for energy
-involves changes in the cytoskeleton
What is Endocytosis?
Cell membrane pinches off to form vesicle = molecule taken into cell
What is Exocytosis?
Vesicle fuses with cell membrane = molecule released from cell
What is phagocytosis?
Used to engulf large objects
What is an aquaporin?
Channel proteins that specifically allow water to cross cell membrane.
What is osmosis?
Water moves across membrane toward the side with a higher solute concentration.
What does it mean if cell A is isomostic to cell B?
Cell A has equal number of solute particles/L as cell B.
What does it mean if cell A is hyperosmotic to cell B?
Cell A is more particles/L than cell B.
What does it mean if cell A is hyposmotic to cell B?
Cell A has fewer particles/L than cell B.
If surrounding solution is hyperosmotic to the cell, the solution is ______tonic to the cell. So water will move _____.
hyper;out
If surrounding solution is hypoosmotic to the cell, the solution is _____tonic to the cell. Water will move _____.
hypo;in.
What is Tonicity?
Used to predict water movement in/out of cell that depends on concentration difference in nonpenetrating solutes across the cell membrane.
What is electrical force/gradient?
When the overall charge is different on one side of a membrane than the other.
What is the Equilibrium potential of K+?
-90mV
What is the Ex of Na+?
+60mV
What is the Equilibrium potential of Cl-?
-63mV
What is the membrane potential? What does it arise from?
At the resting membrane potential, no ion species is at its equilibrium potential. Membrane potential (Vm) arises from weighted contributions of each ion’s Ex based on:
1. Ion’s concentration gradient
2. Ion’s permeability
What is the value of the resting membrane potential?
-70 mV
How are electrical signals produced?
Gated channel opens or closes which changes an ion’s membrane permeability and the resting membrane potential.
What is depolarizaton?
Vm becomes more positive
What is hyperpolarization?
Vm becomes more negative
What is repolarization?
Vm returns to original value
During electrical signaling, how does permeability and ion concentration change?
Only permeability changes, ion concentrations do NOT change.
What are the type of local cell-to-cell communications?
A. Gap Junctions
B. Juxtacrine
C. Autocrine
D. Paracrine
What is gap junction cell signaling?
Direct cytoplasmic transfer of signal
What is juxtacrine cell signaling?
Direct contact between membrane molecules of 2 cells
What is autocrine cell signaling?
Signal diffuses to the cell that secreted it. “Note to self”
What is paracrine signaling?
Signal diffuses to nearby cells.
What are the types of long distance signaling?
- Hormones
- Neurons
How do hormones communicate between cells?
Hormones secreted into the blood by endocrine cells are carried to receptors.
What are the type of neurocrine secretions?
- Neurotransmitter
- Neurohormone
- Neuromodulator
What does a neurotransmitter do?
Diffuse across synapse (short distance) to have rapid effect
What does a nuerohormone do?
Secreted into the blood (long distance).
What does a neuromodulator do?
Similar to NTs but slower and long-lasting effects; can modify effect of NT
What are the receptors for lipophilic signal molecules?
-Intracellular
-slow, long-lasting response (gene expression)
What are the receptors for lipophobic signal molecules?
-Membrane receptor-extracellular binding site
-Rapid, brief response
What are the types of lipophobic receptors?
- Receptor channel
- G-protein coupled receptor
- Receptor enzyme
- Integrin receptor
What is the general concept of a signal transduction pathway for a lipophobic signal molecule?
- ligand binds to membrane receptor
- receptor activates intracellular signal
- activates effector proteins
- produces cellular response
What is a cascade?
Each activated molecule in turn activates the next molecule.
What is amplification?
One ligand results in many intracellular signal molecules
What is an amplifier enzyme?
Produces second messenger molecules.
What defines second-messenger molecules?
Small, fast-diffusing
What are protein kinases?
Phosphorylate (activate or inactivate) other proteins
How do G-protein coupled receptors work?
- When extracellular receptor is activated the cytoplasmic G-protein exchanges GDP for GTP
- GTP-bound form activates other proteins
- GTPase activity converts GTP to GDP
- GDP-bound form is inactive
What is the GPCR-cAMP system?
- Activated G proteins activate adenylyl cyclase
- Adenylyl cyclase converts ATP to cyclic AMP.
- cAMP activates protein kinase A
- Protein kinase phosphorylates other proteins.
In the GPCR-cAMP system, the 2nd messenger is.
cAMP
In the GPCR-cAMP system, adenylyl cyclase is a ________.
amplifier enzyme
What is the GPCR-phospolipase C system?
- Activated G proteins activate phospholipase C
2.Phospholipase C converts phospholipid into DAG & IP3 - DAG activates protein kinase C
- IP3 opens Ca2+ channels allowing Ca2+ to be released from ER
What is the GPCR-phospolipase C system?
- Activated G proteins activate phospholipase C
2.Phospholipase C converts phospholipid into DAG & IP3 - DAG activates protein kinase C
- IP3 opens Ca2+ channels allowing Ca2+ to be released from ER Wha
What is the GPCR-phospolipase C system?
- Activated G proteins activate phospholipase C
2.Phospholipase C converts phospholipid into DAG & IP3 - DAG activates protein kinase C
- IP3 opens Ca2+ channels allowing Ca2+ to be released from ER W
What are the second messengers in the GPCR-phospholipase C system?
Ca2+, DAG, & IP3
What is the amplifier enzyme of the GPCR-phospholipase C system?
Phospolipase C
What is an example of an indirectly gated channel?
Ligand activates GPCR which gates ion channel
How are signals modulated and regulated?
-Receptors show specificity & competition
-Receptors may have more than one ligand
-Ligands may have more than one receptor
What are receptor isoforms?
The type of receptor that matches to a ligand can have different variations that each lead to a different pathway and action.
What is endogenous mean?
Ligand normally produced in the body.
Define exogenous.
From outside the body.
What is an agonist?
A competing ligand that is similar enough to an endogenous molecule that it can bind to the receptor & elicit the same response.
What is an antagonist?
A competing ligand that binds & elicits no response (blocks receptor activity)
What is upregulation?
Increase cell response by adding receptors.
What is downregulation?
Decrease cell response by removing receptors OR decreasing their binding affinity.
How can a signal be terminated?
-Inactive or remove the ligand
-GTPase activity of G-proteins
-Inactivate 2nd messengers
-Pump Ca2+ back into ER
-protein phosphatases
What is tonic control? What is an example?
Signal is always present, but changes in intensity (volume knob). Ex: blood vessel diameter
What is antagonistic control?
Opposing signals send parameter in opposite directions (balancing input from parasympathetic vs. sympathetic nervous system based on environment. )
What is a hormone?
Signal molecules for long distance communication, secreted into the blood by endocrine cells.
What are characteristics of a hormone?
-Elicit response only in cells that have receptor
-Exert effects at low concentrations
-Signal must be terminated
What are the 3 classifications of hormones?
Peptide, steroid, and amine
How are peptide hormones synthesized & released?
-Synthesized from a preprohormone that is converted to a prohormone and transported to Golgi complex then converted to active hormone & stored in vesicles.
-Released by exocytosis
What are the characteristics of a peptide hormone?
-Water soluable
-short half-life
-bind to membrane receptors
-rapid effects
What are the characteristics of a steroid hormone?
-Lipophillic
-Can’t be stored/ synthesized on demand
-Made in only a few organs
-protein carriers
-long half life
-cytoplasmic or nuclear receptor
-slow, long lasting effects
What are the 2 amino acids that Amine hormones can be derived from? What are examples of each and are they lipophillic or lipophobic?
Tyrptophan
- melatonin (lipophillic)
Tyrosine
- catecholamines (epinephrine) (lipophobic)
- thyroid hormones (lipophillic)
What is the simple endocrine pathway?
Endocrine cell directly senses stimulus, integrates, and responds by secreting hormone.
What is the complex endocrine pathway involving insulin?
Pancreatic endocrine cells evaluate 3 input signals when “deciding” whether and how much insulin to secrete.
What hormones does the posterior pituitary secrete? What do they do?
- Vasopressin: water balance in kidneys
- Oxytocin: uterine contractions
What are the 6 tropic hormones that the anterior pituitary releases? What do they do?
1&2. LH & FSH: reproduction & metabolism
3. Prolactin: milk production
4. Thyroid stimulating hormone (TSH): development & metabolism
5. Growth hormone (GH): growth & metabolism
6. Adrenocorticotropic hormone (ACTH): stress & metabolism
What are releasing hormones and where are they secreted from?
Releasing hormones increase secretion by anterior pituitary and are released from the hypothalamic neurons.
Gonadotropin RH (GnRH) stimulates ______ & ________.
LH & FSH
Dopamine inhibits __________.
Prolactin
Thyrotropin RH (TRH) stimulates ________.
Thyroid stimulating hormone (TSH).
Growth Hormone RH (GHRH) stimulates _______.
Growth Hormone (GH)
Corticotropin RH (CRH) stimulates _______.
ACTH
What is the HPG axis? What is an example?
Hypothalamic-pituitary-gonadal axis
GnRH (hypothalamic) –> LH/FSH (pituitary) –> sex hormones (gonads)
What is the HPT axis? What is an example?
Hypothalmic-pituitary-thyroid axis
TRH (hypothalamic) –> TSH (pituitary) –> thyroid hormones (thryoid)
What is the HPA axis? What is an example?
Hypothalamic-pituitary-adrenal axis
CRH (hypothalamic) –> ACTH (pituitary) –> cortisol (adrenal cortex)
What is long-loop feedback?
Peripheral gland secretion inhibits secretion by hypothalamus & anterior pituitary
What is short-loop feedback?
Anterior pituitary secretion inhibits secretion by hypothalamus
What is the difference between non-penetrating and penetrating solutes?
Non-penetrating: cannot move across the membrane, therefore water will move and shrink or expand a cell
Penetrating: Can move across a membrane
Facilitated diffusion is synonymase with _____ diffusion.
Passive
What is the correct sequence in the secretion of a peptide hormone such as insulin?
- Production of preprohormone in rough ER
- Production of prohormone
- Transport to Golgi complex
- Storage in vesicle
- Exocytosis
What does phosphodiesterase (PDE) do?
Breaks down cAMP to terminate signal.
What is an example of a receptor isoform?
Epinephrine can bind to different forms of the adrenergic receptor.One form will dilate blood vessels, while the other form will constrict blood vessels.
What lipophobic receptor type binds to the extracellular matrix?
Integrin
What lipophobic receptor type is the fastest?
Receptor Channel
What kinds of transport can a carrier protein use?
- Facilitated and Active gradients
- Primary & Secondary ATP
