The Sodium/Potassium pumps serves to maintain the....
resting membrane concentration.
The Na+/K+ atpase pump ratio is...
Three sodiums out for every two potassiums in.
The Na+/K+ atpase is the most important...
active transport system.
The purpose of the pump is to maintain proper
concentration gradients. The right amounts of potassium inside the cell and sodium outside the cell.
If there is no potential different between the intracellular and extracellular environments then the cells are no longer....
excitable.
The 5 steps of the ATPase pump
1. The transport protein binds 3 Na+ from the cytosol inside the cell.
2. The transporter is phosphorylated by ATP, donating a phosphate group. The bond formation powers a conformational change in the protein.
3. The Na+ is released to the extra-cellular
The sodium gradient across the membrane is...with more sodium....
150: 15 or 10:1, outside the cell.
The potassium gradient across the membrane is...with more potassium...
5:150 or 30:1, inside the cell.
The relative permeability of the cell membrane to sodium is...
1.
The relative permeability of the cell membrane to potassium is...
25-30.
It is much easier for .... to diffuse down its concentration gradient.
Potassium
The ATPase pump makes a ....contribution to the membrane potential difference.
negligible, -1mV to -3 mV
The concentration gradients of sodium and potassium are essentially ....
constant because it takes so few ions to establish large changes in the electrical gradient.
Potassium's equilibrium constant is..
-90 mV
Sodium's equilibrium constant is...
+60 mV
The cell's resting membrane potential is...
-70 mV
Actions potentials swing the membrane potential.... from...mV to ....mV.
100 mV, -70 to +30
Theshold potential is ...
-50 to -55 mV
The duration of an action potential is...in a given cell type.
always the same.
At threshold potential, the membrane become .....times more permeable to Na+ than to K+.
600
At threshold, the activation gates of the Na+ protein .... and the deactivation gates .....
open, begin slowly closing.
At the peak of action potential, the concentration gradient for K+ is...and the electrical gradient...
is outward and the electrical gradient is outward.
Hyperpolarization results from...
slow closing of the K+ gates.
Basic Parts of the Neuron
1. dendrites
2. cell body
3. axon hillock
4. axon
5. axon terminals
Dendrites
1. "Input zone"
2. Receives incoming signals from other neurons
3. Carries information to the cell body
Cell body
1. "Soma"
2. Also part of the "Input Zone"
3. where the nucleus and organelles are found
Axon hillock
1. Where the cell body meets the axon
2. action potentials are initiated at the axon hillock
Axon
1. the nerve fiber
2. single elongated tubular extension that conducts the action potential away from the cell body.
3. conducting zone of the neuron
Collaterals
side branches of the axon
Axon terminals
1. terminal end of the axon
2. release chemical messengers that influence other cells with which they come into close association.
3. Output zone of the neuron
Contiguous conduction
Conduction in un-myelinated axons, the action potential spreads along every patch down the length of the axon.
Schwann cells are found in the...
peripheral nervous system.
Oligodendrocytes are found in the
central nervous system.
The two factors that dictate speed of the action potential are...
1. myelination
2. axon diameter
Mylinated fibers conduct .... time faster than unmylinated.
50
The largest myelinated fibers conduct at ...mph.
270
The smaller ones in the digestive system conduct at ...mph
2
8 common neurotransmitters
1. acetylcholine
2. dopamine
3. norepinephrine
4. epinephrine
5. serotonin
6. glycine
7. glutamate
8. Gamma-aminobutryric acid (GABA)
In contrast to neurotransmitters being stored in small synaptic vesicles, Neuropeptides are stored in...
Dense-core vesicles
And example of a neuropeptide is.... and effects the "full" feeling after eating.
CCK,Cholecystokinin
The three possible synaptic drug interactions
1. altering the synthesis, axon-al transport, storage, or release of neurotransmitter
2. modifying the neurotransmitter interaction with the postsynaptic receptor
3. influencing the neurotransmitter reuptake or destruction
Effect of cocaine
Blocks the re-uptake of the neurotransmitter dopamine at the presynaptic terminals.
Effect of tetanus toxin
Prevents the release of the inhibitory neurotransmitter GABA which causes spastic paralysis.
Effect of Strychnine
Competes with inhibitory neurotransmitter glycine at the postsynaptic receptor site also causing spastic paralysis.
4 types of extra cellular chemical messengers
1. Paracrine secretion
2. Neurotransmitter secretion
3. Hormonal secretion
4. Neurohormone secretion
Paracrine secretion
1. local chemical messengers that do not enter the blood stream
2. exert an effect only on immediate neighboring cells
3. ex. Histamine, which is released as an inflammatory response
Neurotransmitter secretion
1. a neuron secretes short range chemical messengers in response to electrical signals.
2. diffuse across narrow space to act locally on adjoining cell (other neurons, muscles, or glands)
3. ex. Acetylcholine
Hormone secretion
1. long range messengers
2. secreted into the blood stream by endocrine glands
3. exert effect on target cells some distance away from release site
4. ex. insuline
Neurohormones
1. hormones released into the blood stream by neurosecretory neurons
2. distributed through the blood stream to distant target cells
3. es. Vasopression
Another name for the binding of an extracellular messenger is..
first messenger
After the first messenger binds to the surface membrane receptor the desired intracellular response happens by 3 general means.
1. opening or closing chemically gated receptor channels,
2. activating receptor-enzyme
3. activating second messenger pathways via G-protein coupled receptors
Endocrinology is defined as the...
Homeostatic activities accomplished
by hormones.
Two groups of hormones
1. hydrophilic
2. lipophilic
The results of an extracellular messenger binding to a receptor is..
A receptor channel opens allowing ion entry into the cell which results in the desired response.
The result of an extracellular messenger binding to a receptor enzyme...
a protein kinase site is activated, resulting in phosphorylation of a phosphate group from ATP to an intracellular protein which activates the protein that goes on to produce the desired effect in the cell through signal cascading. (activated protein = ch
Tyrosine Kinase pathway
1. two extracellular messengers (ligands) bind to receptors causing dimerization or joining of two
2. the protein kinase sites on the sides both phosphorylate themselves
3. a protein recognizes these phosphorylated sites and binds to the receptor at the b
Kinases come in 3 classes
1. Tyrosine
2. Threonine
3. Serine
Most extracellular chemical pathways activate second-messenger pathways via...
G-protein coupled receptors, a receptor coupled with a G protein
G-coupled protein pathway
1. a hormone binds to a 7 trans-membrane domain protein receptor and changes its conformation
2. this attracts the trimeric G protein (alpha, beta/gamma) which binds to the now active receptor.
3. The binding changes the confirmation of G protein resultin
About .... of drugs today act on G proteins in some way.
50%
The main second messenger is
cAMP
Example of cAMP dependent protein kinases
PKA (protein kinase A), Ser/Thero kinases
Consist of ...regulatory subunits and ....catalytic subunits.
2 and 2
Normally the tetramer is ....until the ...... bind to the .....subunits releasing the ...... subunits.
Inactive, cAMP, regulatory, catalytic
Neurotransmitters are the same no matter what type of cell they are found in. What differs is the....
receptor type.
Acetycholine is .....in skeletal musclse and .....in cardiac muscle.
Excitatory (influx of Na+, depolarizing), inhibitory (outflow of K+,hyper polarizing)
Physiology is...
The Study of functions of living things
Physiology is the brother of....
anatomy.
Levels of organization of the body
1. chemical
2. cellular
3. tissue
4. organs
5. body system
6. organism
The basic cell functions
1. obtain nutrients and oxygen from the surrounding environment
2. perform chemical reactions that provide energy for the cell
3. eliminate wastes, like carbon dioxide
4. regulate exchange of materials between cell and its surrounding
5. Reproduce
Cells that don't reproduce
1. nerve
2. muscle
(lose their ability to reproduce early in development)
Tissues are...
groups of cells with similar structure and specialized function.
Four primary types of tissues
1. muscle
2. nervous
3. epithelial
4. connective
Three types of muscle tissue
1. skeletal (moves the skeleton)
2. cardiac (pumps blood out of the heart)
3. smooth (encloses and controls movement of contents through organs)
Nervous tissues are found...
1. in the brain
2. in the spinal cord
3. in nerve cells
Nervous tissue is used for
initiating and transmitting electrical impulses
Epithelial tissue is used to...
1. exchange material between cells and its environment
2. connect the body and it's organs to the environment
Epithelial tissue is organized into two general types of structures
1. epithelial sheets
2. secretory glands
The purpose of connective tissues are to
connect, support, and anchor various body parts
Connective tissues are distinguished by...
having very few cells.
Examples of connective tissues are
tendons-attach skeletal muscle to bone
ligaments-attach bone to bone
blood-transports bodily materials
Organs consist of...
two or more types of tissues that work together to perform a particular function
A body system is defined as...
A group of organs that perform related functions and interact to accomplish a common activity for the survival of the whole body.
Systems work...
closely together to achieve homeostasis.
The human body consists of
11 systems.
weird one is integumentary
Homeostasis is defined as
the ability to maintain a relatively stable internal environment despite fluctuations in the external environment.
Homeostasis happens on a ... by .... basis.
Cell by cell
The two components of the extracellular environment are
Plasma and interstitial fluid
7 Main factors that are homeostatically regulated are
1. the concentration of nutrient molecules
2. the concentration of O2 and CO2
3. the concentration of waste products
4. pH
5. concentration of water, salt, and other electrolytes
6. volume and pressure
7. temperature
The contribution of the circulatory system to homeostasis is
carrying materials from one part of the body to another.
The 3 contributions of the digestive system to homeostasis are
1. breaking down food into small molecules
2. the transfer of water and electrolytes to body cells
3. eliminating undigested food residues to external environment in the feces
The 2 contribution of the respiratory system to homeostasis are
1. to get O2 and eliminate CO2
2. to maintain proper pH of the internal environment
The contribution of the urinary system to homeostasis is
1. removing excess water, salt, acid and other electrolytes from plasma and passing them in the urine in efforts to keep the blood clean.
The 4 contributions of the skeletal system to homeostasis are
1. to provide support and protection for soft tissues and organs
2. to serve as storage for calcium
3. enable movement of the body
4. bone marrow produces red blood cells
The 2 contributions of the integumentary system are
1. serving as an outer protective barrier
2. regulating body temperature
The 2 contributions of the immune system are
1. defend against foreign invaders and body cells that have become cancerous
2. paves the way for repairing and/or replacing damaged or worn out cells
The 2 contributions of the nervous system are
1. controlling and coordinating bodily activities that require rapid responses (reflexes)
2. detect and initiate reactions to changes in external environment
The 3 contributions of the endocrine system
1. regulate numerous cellular activities through hormone secreting glands
2. controlling the concentration of nutrients and adjusting kidney function
3. controlling the internal environments volume and electrolyte composition.
Contribution of the Reproductive system
1. essential for the perpetuation of the species but not for individual survival
The 3 things the homeostatic control system must be able to do is
1. detect deviations from normal in the internal environment
2. integrate this info with other relevant information
3. make appropriate adjustments in order to restore factor to it's desired value
The 2 things homeostasis disruption can lead to
1. illness and death
2. abnormal functioning of the body (disease)
In the cell membrane, we only find carbohydrates on the..
outside surface. Glycolipids and glycoproteins
We find cholesterol...
tucked between phospholipid molecules.
The purpose of the cholesterol is to
prevent fatty acids from aggregating and crystallizing.
The carbohydrates also help the cell membrane's...
fluidity and stability
Proteins are found
attached to or inserted within the lipid bilayer.
Proteins serve as
1. carrier molecules (transport molecules)
2. membrane bound enzymes
3. receptor sites
4. cell adhesion molecules
5. cell to cell interactions
The functions of the lipid bilayer is to
1. form the basic structure of the membrane
2. create a hydrophobic barrier in order to maintain certain ion concentrations
Membrane carbohydrates serves as
1. self identity markers enabling like cells to identify each other in order to build tissues
2. enable cells to recognize dislike cells so they don't invade each others territory
Cell to cell adhesion
1. binds group of cells into tissues and packages them into organs
Once arranged, cells are help together by three different means
1. extracellular matrix
2. CAMS, cell adhesion molecules in cells, like velcro
3. specialized cell junctions (gap junctions)
Proteins making up the fibers in the extracellular matrix include.
1. collagen
2. elastin
3. fibronectin
Collegen is a..
protein that forms flexible fibers or sheets.
A vitamin C deficiency leads to
scurvy, brittle collagen.
Elastin is..
a rubbery protein that promotes flexibility, mostly found in lungs.
Fibernectin
promotes cell adhesion by holding cells in position. A reduction in this leads to cancer metastasis.
Cell membranes are selectively permeable, the two properties that influence whether or not they can cross the cell membrane is
1. the relative solubility of a particle
2. the size of the particle
The 2 types of unassisted membrane transport are
1. diffusion
2. osmosis
The 4 types of assisted membrane transport are
1. carrier-mediated
2. facilitated transport
3. active transport
4. vesicular transport
Diffusion
movement of particles from an area of high concentration to an area of lower concentration.
Osmosis
movement of water from an area of low concentration to an area of high concentration of solutes.
Hypo
less than.
Hyper
more than.
The 2 types of carrier mediated transport are
1. facilitated diffusion
2. active transport
Facilitated diffusion ....
does not require energy. passive.
Active transport
requires energy. active.
The 3 characteristics that determine the kind and amount of material that can be transferred across the membrane are...
1. specificity
2. saturation
3. competition
Specificity refers to
carrier proteins transporting specific types of substances.
Saturation refers to
the fact that there are only so many of one type of carrier protein in a cell.
Competition refers to
the fact that closely related compounds can compete to be transported.
Characteristics of facilitated diffusion are
1. substances move from a higher concentration to a lower concentration, passively.
2. a solute binds to the carrier protein which changes its conformation and gets released on the other side of the membrane.
Characteristics of active transport
1. moves substances against their concentration gradients
2. requires ATP (primary active transport)
3. or it can use concentration gradients of another solute (secondary active transport)
Antiporters are...
the solute and the high concentration ion move in different directions.
Symporters
the solute and the high concentration ion move in the same direction.
Vesicular transport is when
material is moved into or out of the cell wrapped in a membrane.
Vesicular transport is ...
active, it requires energy.
The two types of vesicular transport are
1. endocytosis
2. exocytosis
Endocytosis has two forms....
1. pinocytosis
2. phagocytosis
Pinocytosis is
cell drinking, non selective uptake of extracellular fluids
Phagocytosis is
cell eating, selective uptake of solid particles.
Exocytosis
provides a mechanisms for secreting large molecules.
Depression medicines work by ...
prohibiting the re-uptake of neurotransmitters by blocking endocytosis or serotonin.