Cell & General (1) Flashcards
Define the term physiology
The study of living things and how they function.
Helps us understand how the body works, from the smallest part (cells) all the way to the whole body
Define homeostasis
The maintenance of a relatively stable and dynamic internal environment; CONSTANCY
The goal is to maintain variables within a tight range based on the set point
Ex. Body must maintain mass balance
Ex of homeostasis, positive and negative
Negative: temperature and blood glucose level
Positive: childbirth and lactation
Neg vs pos feedback loops definition and difference
Negative feedback loops: feedback reduces the difference between the desired setpoint and the actual value
Positive feedback loops: feedback increases the difference between the normal setpoint and the actual value
In negative we have deviated from baseline and want to go back, in positive we want to keep deviating
Feedforward control and examples
Feedforward control is an anticipatory response: initiation of a response in anticipation of the stimulus
EX:
- Sight, smell or thought of food is enough to initiate salivation and digestion
- Increase in ventilation (breathing) as soon as exercise begins
Describe the biological hierarchy of organization in the context of functional compartments: cells, tissues, organs
order goes smallest to largest:
atoms, molecules, cell, tissue, organ, organ system, organism
Compartmentalization allows for separation of complex processes
Describe the biological hierarchy of organization in the context of fluid compartments: Intracellular vs Extracellular
ICF: all fluid within cells; this fluid is ⅔ of the total body water volume (28L)
- Has mainly sodium
ECF: all fluids outside cells: this fluid is ⅓ of the total body water volume
- Interstitial fluid = lies between the circulatory system and the cells (11L)
- Blood plasma = the liquid matric of blood (3L)
- Has mainly potassium
List cell junctions
gap, anchoring and tight
List the four different tissue types found in the human body
muscle, epithelial, connective, neuronal
Types of epithelial tissue
Exchange, protective, ciliated, transporting, and secretory
Describe epithelial tissue
Lining that protects the internal environment of the body and regulates exchange of materials between internal/external environment
Not excitable
Types of connective tissue cells
loose, dense, adipose, blood, cartilage, bone
Loose connective tissue
elastic tissues under skin and between some cells
- Very flexible with multiple cell types and fibers
- Has fibrolasts: cells that secrete matrix proteins
- Ground substance = matrix of loose connective tissue
Dense connective tissue (and 2 ex)
provides strength and flexibility
- Regular: tightly packed and organized; tendons, blood vessel walls
- Irregular: has fibers that are not arranged in parallel bundles; collagen and dermis
Adipose tissue
provide energy storage, insulation from extreme temperatures and cushioning around soft organs
in white fat, the cell cytoplasm is almost full of lipid droplets
Blood
composed of liquid matrix (plasma), RBC, WBC, platelets
Cartilage
has firm but flexible matrix secreted by cells called chondrocytes
Bone
forms when osteoblasts deposit calcium phosphate crystals in the matrix
Types of muscle tissue cells
smooth (GI tract), skeletal and cardiac
Describe muscle tissue
Generates contractile force
- Excitable
Describe neuronal tissue
Neurons transfer information chemically or electrically via action potentials whereas glial cells give support for neurons
- Neuron are excitable but glial cells are not
- Glial cells kind up make up neuronal cells
Selective permeability and membrane transport
Type of membrane transport that is more likely for small, uncharged molecules: O2, CO2, (H2O too but thats better with channel transport)
- Membrane transport is less likely for molecules such as Ca2+, Na+, K+, and glucose
Hydrophobic phospholipid bilayer and membrane transport
Membrane transport is more likely for hydrophobic molecules because they are water hating, like the inside of the membrane
Proteins and membrane transport
- aides in bringing in larger/charged molecules, and also help with cell communication and recognition
- types of membrane proteins: transmembrane receptors, peripheral, cell and lipid anchored
Carbohydrates and membrane transport
- glycoproteins and glycolipids aides in cell communication, protection and recognition
Cholesterol and membrane transport
aides in membrane fluidity and permeability
Types of transport membrane mechanisms
non facilitated transport: simple diffusion
facilitated diffusion: protein mediated (passive and active), vesicular
Key factors that affect SIMPLE? diffusion
lipid solubility, molecular size, concentration gradient, membrane surface area, composition of lipid bilayer
Breakdown of protein mediated transport
- protein mediated has channels vs transporters, 2 subcategories: passive aka facilitated diffusion, active (primary and secondary)
Define channels
Channels = proteins in protein mediated transport that create water-filled pores linking extracellular and intracellular environment
Describe channels in protein mediated transport
Act via facilitated diffusion, ALWAYS with passive transport
Are selective about which molecules pass via ion or water channels
Can have gates to regulate flow
Ion channels: sodium, potassium, calcium, chloride
describe speed of channels in protein mediated transport
Fast transport/diffusion but are specific to a type of group
Define transporters
proteins in protein mediated transport that open to ECF or ICF, one at a time
describe transporters in protein mediated transport
Act via facilitated diffusion OR active transport
May be selective but can carry larger molecules than channels (glucose)
describe speed of transports in protein mediated transport
Flip flop mechanism heavily slows the process due to switching conformation
Explain primary active transport
directly uses ATP as its energy source (ATPases)
Ex: NaK pump
Explain secondary active transport
indirectly uses potential energy stores in concentration gradient from other molecules
- Need ATP to put PE in concentration gradients from other molecules
- Occurs via symport or antiport mechanisms
- Ex: Na + glucose transporter
Compare and contrast active vs passive transport
Passive = facilitated diffusion
- Channels or transporters do this
- Molecules move down their concentration gradient towards equilibrium
- Ex: glucose transport
Active = requires energy
- Only pumps or transporters do this
- Molecules move up (against) their concentration gradient and as a whole, the system moves away from equilibrium
- Ex: NaK pump
Breakdown of vesicular transport
endocytosis, exocytosis, phagocytosis
endocytosis
= welcoming a substance into the cell via fusion with the membrane
- Ligand binds to the membrane receptor, receptor-ligand migrates to a clathrin coated pit, fusion with membrane occurs
- Vesicle loses clathrin coat and receptor-ligand are taken by endosome and separated so receptor is engulfed by transport vesicle and ligand is taken to lysosome for trash or golgi for processing
exocytosis
= kicking a substance out of the cell via engulfing it in a vesicle and then fusing it with the membrane
- Transport vesicle engulfs substance and fuses with membrane to perform release
- Ex: NT release
Phagocytosis
= ingests and eliminates pathogens or foreign substances
RI FFF
- particle recognition, particle ingestion, early phagosome formation, late phagosome formation, and phagolysosome formation.
Transcellular transport
Form of epithelial cell transport: occurs through cells via simple diffusion, facilitated diffusion, active transport, and endo/exo
- Ions or molecules cross both apical and basolateral membranes
- Apical = with villi, and faces the lumen
- Basolateral = faces the ECF
Paracellular transport
Form of epithelial cell transport: occurs between adjacent cells to get to or from lumen
- Regulated by presence of tight junctions
Moves ions and water
Explain disequilibrium in the context of chemical gradients
Disequilibrium results from a differing concentration of ions and molecules, inside vs outside of the cell
- When equilibrium is reached, the deviation of ion charges of molecules inside vs outside the cell should be the same as the deviation of concentration of molecules in/out is the same
Explain disequilibrium in the context of electrical gradients
Disequilibrium results from a differing net ion charge, inside vs outside of the cell
- When equilibrium is reached, the deviation of ion charges of molecules inside vs outside the cell should be the same as the deviation of concentration of molecules in/out is the same
Explain disequilibrium in the context of resting membrane potential
RMP = net charge difference btw ICF and ECF @ rest
- Results from unequal distribution of ions of each side of the membrane… this results in a state of disequilibirum
Nernst Equation
used to calculate the equilibrium potential
- if CM is only permeable to one type of ion, the membrane potential = the nernst potential of that ion
Electrochemical driving force for ion flow
depends of Vm and Ex
- Vm = membrane potential difference
- Ex = equilibrium potential
= Ex - Vm
GHK equation
predicts the RMP that results from the contribution of all ions that can cross the membrane
- Based on combined contributions of concentration gradients and relative membrane permeability of each ion
how does the Na+-K+-ATPase helps maintain concentration and electrical gradient
Helps maintain the RMP by maintaining the Na and K concentration gradients during ion movement through leak channels
Modes of local distance communication
gap junctions, contact dependent, autocrine, paracrine
local distance communication in gap junctions
forms direct cytoplasmic connections between adjacent cells
local distance communication in contact dependent
requires interaction between membrane molecules on 2 cells
local distance communication in autocrine signaling
signals act on the same cell that secreted them
local distance communication in paracrine signaling
signals are secreted by one paracrine cell and diffuse to adjacent cells
Modes of long distance communication
neuronal, endocrine
long distance communication in neuronal context
involves neurohormones and neurotransmitters
neurohormones
= hormone that is a chemical that is released by neurons in neural tissue into blood, for action at distant targets
Moves over a long distance
neurotransmitter
= chemicals secreted by neurons that diffuse across a small gap to get a target cell
Moves over a small distance
Ex. acetylcholine
long distance communication in endocrine context
involves hormones
hormone
= secreted by endocrine cells/glands into blood, only target cells with receptors for the hormone will response to the signal
Ex. insulin
3 types of membrane signaling receptors
receptor-channel, enzyme-channel, G protein coupled receptors
name the 4 major features of a signal transduction pathway
receptors, signaling cascades, signal amplification, second messengers
receptors in a signal transduction pathway
activates the intracellular signal molecules
Presence of receptors determines whether a cell responds to a signal molecule
signaling cascades in a signal transduction pathway
system that helps prevent deviating cellular responses
signal amplification in signal transduction pathways
volume control, acts at each step
second messengers in signal transduction pathways
alters target proteins that end up creating a response
describe the enzyme-linked receptor signaling pathway
ligand binds to receptor, which activates associated enzyme
Ex. insulin receptor
describe the GPCR signaling pathway
AC & PLC: ligand binds to a receptor that is physically coupled to a guanosine nucleotide-binding G protein
- Binds to and activates G proteins that are made up of 3 subunits
- G protein activation leads to direct alteration of ion channel gating or alteration of a different enzymes activity
- Activation of AC adenylate cyclase will always trigger production of cAMP which then activates protein kinase A
- Activation of PLC phospholipase C always leads to production of IP3 inositol triphosphate and activation of protein kinase C
describe the ion channels signaling pathway
acts as a receptor for ligand to bind to, gated by ligand binding
describe the Ca2+ signaling pathway
Enters cells via voltage, ligand or mechanically gated channels
Can be released from stores by second messengers
