synapse in which an action optential in a presynaptic neuron increases the probability of an action potential occurring in postsynaptic cell
what is an exitatory synapse?
acetylcholine and glutamate
excitatory neurotransmitters
- in neuronal cell body
- presynaptic terminal
where are neurotransmitters synthesized ?
in the synaptic cleft
where is the calcium located that flows into the cell during action potential
- calcium binds to synaptotagmin on vesicle
- after the binding the protein interacts with SNARE protein which induces the fusion of the vesicle membrane and the presynaptic membrane
what happens after the calcium has entered the presynaptic terminal ?
the neurotransmitters enter the synpatic cleft and bind to receptors on the postsynaptic cell membrane - these receptor go under conformational changes that may open a transmembrane channel forming an EPSP or IPSP
what happens after the vesicle fuses with the presynaptic membrane ?
protein that Ca2+ binds to in the vesicle releasing from the presynaptic terminal - this protein binds to SNARE
what is synaptoragmin ?
K+ out and Cl- in
increased permeability for ______ and ______ in IPSP
Na+
in EPSP the cell is more permeable for
the principle that a motor nerve responds to the alternation of value of an electric current from moment to moment
define the law of exitation
The all-or-none law is a principle that states that the strength of a response of a nerve cell or muscle fiber is not dependent upon the strength of the stimulus.
- Essentially, there will either be a full response or there will be no response at all for
describe the all or non law
Strength duration curve is a graph between electrical stimuli of different intensities and recording the time needed by each stimulus to start the response.
explain strength duration curve
it is the lowest intensity with indefinite pulse duration to form an action potential or a muscle tension contraction
define rheobase
Chronaxie is the minimum time required for an electric current to double the strength of the rheobase to stimulate a muscle or a neuron
define chronaxy
A = 2x rheobase
B = chronaxie
C = rheobase
X = stimulus strenght
y = stimulus duration
name the values
0.3-0.5 ms
how long time is the chronaxie in a healthy nerve tissue ?
the curve is shifted up and to the right - need more stimulus and more time
how is the strength duration curve in a muscle fibre or in a damaged nerve fibre different from a healthy nerve fibre ?
chronaxy and rheobase
_______ and _______ are points defined for strength and duration of excitable tissue in the body
chronaxymeter
______ is used for measuring the excitability in a tissue:
- rheobase
- chronaxie
name two things on the strength duration curve that define stimulus of an excitable tissue
the study of relationship between different forms of energy involved in chemical and physical processes
define thermodynamics
the ability of an object to receive a heat from another object spontaneously (or give)=
define temperature
thermal balance or imbalance
what does temperature describe in thermodynamics ?
it is caused by the movements of particles
what is causing the temperature to increase or decrease?
Celcius, farenheit or kelvin (the basic unit of thermodynamics)
name the units of temperature
energy cannot be created or destroyed, it can only be converted from one form to another - the total internal energy of an isolated system is constant
define the first law of thermodynamics
the total entropy of an isolated system always increases in a spontaneous process
define the second law of thermodynamics
heat is a change of thermal energy - the energy stored within the object in a form of irregular movement of particles (
define heat
Joules
unit for heat
radiation only
in vacuum heat can only be transferred by
it can change from one form of energy to another form - even into work
abilities of heat
only from the body with higher thermal energy to the body with lower thermal energy
under what circumstances can heat be transferred spontaneously from one body to another ?
Heat describes the transfer of thermal energy between molecules within a system and is measured in Joules. Heat measures how energy moves or flows.
Temperature describes the average kinetic energy of molecules within a material or system and is measured i
describe the difference between heat and temperature
1. conduction
2. convection
3. infrared radiation
4. evaporation
name physical ways to spread heat
A = evaporation
B = convection
C = radiation
D = conduction
name the ways to spread heat
conduction occurs as rapidly moving or vibrating atoms and molecules interact with neighboring particles, transferring some of their kinetic energy - in two solid substances
explain conduction
it is the flow of warm substances in gases and liquid
explain convection
the heat transferred in a form of electromagnetic radiations by photons
explain infrared radiation
done by evaporation of sweat - gives the heat loss, also against the thermal gradient
explain evaporation
the evaporation
which way of transferring heat is the most effective one ?
the amount of heat necessary for raising the temperature of the object by 1K
what is thermal capacity ?
the amount of substance in the object
thermal capacity depends on
J/K
unit of thermal capacity
the amount of heat necessary for raising the temperature of 1K of the substance by 1K
define specific heat
J/kg*K
unit for specific heat
volume, pressure and temperature
what conditions do specific heat and thermal capacity depend on ?