Definitions Flashcards
Vital Capacity
The maximum volume of air that can be inhaled to or exhaled from the lungs
Viscocity
Physical property of fluids that determines the ease with which the layers of a fluid move past each other
when a substance have lower viscosity, than easier for a substance with higher viscosity to move through are past.
Vesicle
small, spherical compartment in the cell surrounded by a membrane (e.g. synaptic vesicle)
venule
small vessel connecting the pillaries to veins
- blood go through capillary-venule and veins (blood circulation)
ventilation
air exchange between the lungs and the ambient air
Vena Cava
empty vain; large veins returning from the body to the right atrium were named vena cavae, because they were found empty in hanged persons dissected during medieval times.
- superior and inferior vena cava
- bring blood back to the heart without oxygen from the body
van der Waals forces
relatively weak attraction between atoms and molecules with hydrophobic properties due to the random fluctuation of the electron clouds.
Valsava’s maneuver
sustained expirational effort against a closed airway, e.g. by closing ones mouth or pinching nose.
unsaturated fatty acid
fatty acid containing one or more double bonds
Extra: (one or more double covalent bond between the carbon atoms of the hydrocarbon chain. Different to saturated fatty acid with single bonds and are saturated with hydrogen atoms)
unipolar neuron
nerve cell with only one process
turbulent flow
a flow pattern in which particles of the fluid move irregularly in all directions of the space
T-tubules
invagination of the sarcolemma, carrying excitation to the sarcoplasmic reticulum
triglycerides
lipid molecules composed of three fatty acid residues esterified to glycerol
Extra: function: protection, insulation, energy storage.
tricuspid valve
valve between the right atrium and ventricle
trachea
large respiratory passageway connecting the pharynx with the bronchi of the vertebrate lung
trace elements
elements needed in very low concentration for the normal functioning of the organism (Fe, I, Zn, Co, Mn etc.) Their total amount is about 0.01%.
time constant
time required for an externally included potential change in the membrane to decrease to 37% (1/e) of the original potential.
tight junction
area of the membrane fusion between adjoining cells that prevents the passage of extracellular material between the cells
Tidal volume
volume of air moved during a relaxed inspiration or expiration
thrombosis
blockade of a vessel due to a blood clot formed in the vessel
tetanic contraction
uninterrupted muscular contraction caused by high-frequency motor impulses
tercier structure of proteins
3D, spatial form of the protein chain stabilized by weak interactions (electrostatic, van der Waals)
systole
the portion of the heart beat when the heart muscle is contracting
happens when depolarization reaches the contractile cardiac muscle cells.
surfactant
surface active agent lining the inner surface of the alveoli (in the lungs) which decreases surface tension
surface active substance
(amphipathic - detergent) - its molecules possess both hydrophilic and hydrophobic parts; they tend to line up at the border separating two different phases (lipid-water, water-air, etc.) with the hydrophilic and hydrophobic parts located in the appropriate phase.
Surface active agent
amphipathic molecule bearing both hydrophilic and hydrophobic groups
summation
in time and space; adding up of the effects of two synaptic potentials occuring at the same synapse with short delay or in neighboring synapses concurrently
sucrose
disaccharide built up by glucose and fructose; it is the most common commercially available sweetener
Strenght (energy) of a bond
energy released during the formation of the given bond between atoms - this energy is needed to break apart the atoms
Starling’s hypothesis
theory to explain the production and absorption of interstitial fluid
spirometer
device to measure lung volumes and aspects of breathing
specificity
due to its spatial structure, a receptor, enzyme or transporter molecule can only bind a limited number of substrate molecules
Space constant
externally induced and electronically conducted potential changes in the membrane decrease to 37% (1/e) after traveling a distance equal to the space constant
Sliding filament hypothesis
generally accepted theory explaining muscle contraction by sliding of actin and myosin filaments on each other
Sinoatrial node
specialized cardiac tissue in the right atrium acting as the pacemaker of the heart
side chain
a group bond to the alpha-carbon atom of amino acids; amino acids are distinguished by the chemical composition of this group
septum
muscular tissue separating the left and right atria and ventricle
semipermeable membrane
membrane separating two solutions and limiting the penetration of some solvents from one side to the other, while admitting some other solvents.
semilunar valves
valves at the orifice of the aorta and pulmonary artery
secondary structure of proteins
formation of regular structures (alpha helix, B-sheet) in the peptide chain stabilized by H-bonds
second messengers
small molecules whose concentration changes after the first messenger (signal) attaches to the membrane receptor
Schwann cell
glia cell formin myelin sheath around axons at the pheriphery
scalar electrocardiogram
signal measured in any of the Einthoven leads, corresponding to the projection of the electrical vector of the heart onto a line connecting two electrodes, thus transforming the vector into a scalar variable
saturation
characteristic feature of protein mediated transport processes - by increasing the concentration of the molecules to be transported, increase of the transport speed increases less and less as most of the transporter molecules tend to be occupied after a certain concentration.
sarcoplasmic reticulum
similar to the smooth endoplasmic reticulum; large internal store of Ca++ ions in the muscle fibres
sarcoplasm
cytoplasm of the muscle fiber
sarcomere
are between two z lines in the myofibril
sarcolemma
membrane of the muscle fiber
saltatory conduction
fast conduction of action potentials on myelinated axons; action potentials are only regenerated, thus delayed at noeds of Ranvier, while they pass through internodes by electrotonic conduction with minimal delay - action potentials are “jumping from node to node”, hence the name.
respiratory cardiac arrythmia
changes in the sinus rhythm caused by breathing
repolarization
return of a membrane that has been depolarized to its resting membrane potential
refractory period
period during and immediately after an action potential in which the membrane cannot be excited (absolute refractory period) or has an elevated threshold (relative refractory period)
queaternary structure of proteins
spatial arrangement of peptide chains and non-peptide components of a protein
quantal release
transmitter substances are released in small packages (quanta) from the synaptic terminal
pyramidines
compounds based on a ring containing four C(carbon) and two N(nitrogen) atoms; uracil, thymidine and cytosine, bases in nucleic acids are pyrimidine compounds
Purkinje fibres
modified heart muscle fibres conducting excitation from the bundle of His to the myocardium of the ventricles
purines
compounds based on a two ring structure containing five C(carbon) and two N(nitrogen) atoms; adenine and guanine, bases in nucleic acids are purine compounds
pulse volume
volume of blood pumped by the heart into the circulation during one systole
pseudounipolar neuron
nerve cell with one process that branches near to the cell body forming two equivalent neurits
protein kinase
enzyme catalyzing the transfer of a phosphate group from ATP to a protein
protein
proteios = first in rank (Greek), macromolecule built up by amino acids
projection neuron
nerve cell with a long axon running to remote targets
primary structure of proteins
sequence of amino acids building up the molecule
Pressor area (center)
area in the dorsolateral reticular formation of the medulla; its excitation increase heart rate, constrict vessels, thus increases blood pressure through sympathetic fibres.
preganglionic neuron
autonomic neuron located in the central nervous system that sends an axon into the periphery and synapses onto postganglionic cells
precapillary sphincter
muscular ring at the origin of capillaries regulating blood flow in the capillary
posttetanic potentiation
increased efficacy of synaptic transmission following presynaptic stimulation at a high frequency
postganglionic neuron
autonomic neuron located in a peripheral ganglion that receives input from preganglionic neurons and synapses onto target organs
polysaccharides
macromolecules built up by simple sugar molecules (contain 10-100 monosaccharides).
e.g. glycogen and cellulose
polypnea
rapid breathing (or respiration)
polar
charged substance (or molecule) that can interact with water (hydrophilic).
nonpolar
substance lacking completely or partially separated charges that can be dissolved in lipids
(hydrophobic/lipophilic): cannot interact with water molecules, thus unsolvable in water.
Poiseuille’s law
equation describing the laminar flow of fluids in rigid tubes; as the function of pressure difference, tube diameter and length and viscosity.
pneumothorax
collapse of the lung due to a puncture that penetrates the pleural cavity
plateau
characteristic period in the action potential of the heart muscle cell, during which membrane potential is relatively constant
Phosphorylation
incorporation of a phosphate group into an organic molecule
phospholipid
a lipid that contains one or more phosphate group attached to it.
phosphorus-containing lipid
phosphoglyceride
- glycerol baced phospholipids.
- ubiquitous phosphorus containing lipid; its structure is similar to that of the triglycerides, but one fatty acid is replaced by a phosphoric acid and a nitrogenous compound.
- polar (hydrophilic) head and non-polar (hydrophobic) tail
Phagocytosis
pinocytosis
forms or ways of endocytosis to take up solid particles or fluid into the cell
phagocyte
a cell that ingest other cells, microorganisms or other foreign particles
permeability
ability of a compound to cross the membrane; it depends on the characteristics of the compound and of the membrane
peripheral (extrinsic) protein
protein associated to the external or internal surface of the cell membrane
peptide bond
covalent bond created by condensation (reaction releasing a water molecule) of the amino and carboxyl group of two amino acids
peptide
short protein molecule
paravertebral ganglia
chain of ganglia connected with nerve trunks along the spinal cord that contains sympathetic postganglionic neurons
paracrine communication
communication in which the signal reaches the target cell through the interstitial space
overshoot
part of the action potential, where the membrane potential becomes positive
output of the heart
blood volume pumped by the heart into the circulation in one minute
osmosis
passive diffusion of water; water is moving through the (selectively permeable) membrane from the area of higher concentration of water (solvent) to the area of lower concentration of water - following its concentration gradient.
- from area of low concentration of solute (e.g. sugar) to area of higher concentration of solute.
- from the more diluted solution toward the more concentrated solution.
- osmosis occurs only when a membrane is permeable to water bu not to certain solutes
oligodendrocyte
glia cell in the central nervous system forming myelin sheet around axons passing thorugh its vicinity
nucleotide
building block of nucleic acids formed by purine or pyrimidine base, a ribose or deoxyribose sugar, and phosphate group
nucleoside
similar to nucleotide but contains no phosphate group
non-covalent bonds or weak forces
supplemental, but important interactions between and within biological molecules: electrostatic (ionic) bonds.
e.g. hydrogen bond, result from attraction of opposite charged parts of molecules rather than from sharing electrones
Wan der Waals interaction: the two atomic nuclei are closer together than the sum of the two Van der Waals radi
Node of Ranvier
one of the regularly spaced interruptions of the myelin sheath between two Schwann cells along an axon
Nissl substance
characteristic component of nerve cells corresponding to rough endoplasmic reticulum
nicotinic acetylcholine receptor
ACh receptor at which nicotine mimics the effect of acetylcholine
neutrophil granulocyte
white blood cell (type: granular leukocytes)
- essential part in innate immune system
- containing vesicles stained by neutral stains?
Neurotransmitter (mediator)
signal molecule interacting with receptors in the postsynaptic membrane and usually modifying the membrane potential of the postsynaptic cell
neuromuscular endplate
synapse between the motoneuron and the muscle fibre
neuromodulator
signal molecule changing neuronal functions; it usually has a broader and longer lasting effect than the neutransmitters
neurocrine communication
communication in which the signal reaches the target cell through the synaptic cleft
neurit
process of neuronal cells
- any projection from the cell body of the neuron
Nernst equation
equation for calculating electrochemical equilibrium conditions
NAD
nicotinamide adenine dinucleotide, a coenzyme
myoglobin
iron-containing oxygen-binding protein molecule in the muscles resembling hemoglobin
myofibril
a longitudinal unit of a muscle fiber, made up of sarcomeres and surrounded by sarcoplasmic reticulum
myelin sheet
insulation around axons formed by Scwann cells or oligodendrocytes wrapping the axon into 50-100 layers of membrane
muscle twitch
contraction and relaxation caused by a single action potential in the muscle
muscarinic acetylcholine receptors
ACh receptor at which muscarine mimics the effect of acetylcholine
multipolar neuron
nerve cell with many processes; most neurons are like this.
monosaccharide
simple sugar (ribose, glucose, fructose etc.) - type of carbohydrate
monocyte
large white blood cell with phagocyte function
mitral valve
biscuspid valve between the left atrium and ventricle in the heart
miniature end-plate potential
small, quantal changes of membrane potential in the neuromuscular synapse caused by the spontaneous presynaptic release of transmitter molecules
microvilli
small, fingerlike protrusions of the apical membrane increasing the surface of some epithelial cells
metarteriole
vessel connecting arterioles and venules from which true capillaries originate
memory cell
lymphocyte specialized for the long-term storage of the code to synthesize an antibody
mean electrical axis
direction of the electrical vector of the heart at the peak of the R-wave
maximal ejection
part of the heart cycle following the opening of the semilunar valves during systole
lymphocyte
white blood cell responsible for the production of antibodies
Long term potentiation (LTP)
long lasting increase of efficacy in a synapse following strong stimulation in some parts of the CNS (central nervous system)
lipoprotein
protein molecule containing lipid groups
lipids
organic compounds soluble in nonpolar solvents
- most are hydrophobic - nonsoluble in polar solvents such as water.
- 18-25 % of body mass
ligand
signal molecule that can specifically bind to a receptor
laminar flow
movement of a fluid or air, during which layers are sliding smoothly on each other
lactose
disaccharide formed by glucose and galactose molecules
keto-sugar
sugar containing a ketone group (e.g. fructose)
isotropic
optically homogenous material, transmission is independent of the plane of the polarized light
isotonic contraction
contraction of muscles at constant tension when only length changes
isometric contraction
contraction of muscles at constant length when only tension changes
isometric (isovolumic) relaxation
relaxation of the ventricles while valves are closed and volume is constant (in the heart)
isometric (isovolumic) contraction
contraction of the ventricles while valves are closed and volume is constant (in the heart)
ion pump
active transport process moving ions through the membrane using energy stored in ATP molecules
ion channel
(leakage, voltage dependent, ligand dependent) - pore enabling passage of ions through the membrane; it is formed by intrinsic membrane proteins and is either continously open (leakage) or opened by a change of membrane potential or by the binding of ligand (signal) molecule
intrinsic (integral) protein
membrane protein spanning the membrane from one surface to the other
interstitial space
tissue space between cells
internode
space along a myelinated axon that is covered by a myelinating glial cell (Schwann cell or oligodendrocyte)
inspirational reserve volume
IRV- the air inspired with a maximal inspiratory effort at the end of a tidal inspiration at rest
immunoglobulin
same as antibody, which is a protein molecule produced by the lymphocytes that can specifically bind to antigens
- used by immune system to recognize and neutralize foreign substances, such as bacteria and virus
- recognizes the antigen in the foreign target
antibody
a protein molecule produced by the lymphocytes (B-cells) that can specifically bind to antigens
- same as immuunoglobulin
- used by immune system to recognize and neutralize foreign substances, such as bacteria and virus
- recognizes the antigen in the foreign target
hypopolarization
a shift of the resting membrane potential toward less negative values - a decrease
hyperventilation
increased lung ventilation
occurs when the rate and quantity of alveolar ventilation of carbon dioxide exceeds body’s production of carbon dioxide.[1][2] Hyperventilation can be voluntary or involuntary.
hyperpnea
breathing that is faster or deeper than normal
hydrophobic (lipophilic)
nonpolar molecule that is unable to interact with water molecules, thus insoluble in water
hydrophilic (lipophobic)
polar or charged molecule that is able to interact with water molecules, thus can be dissolved in water
hydrogen bond
a type of non-covalent bond or weak force
- weak interaction between an H-atom bound to a highly electronegative atom (O, N) in a molecule and another highly electronegative atom (O, N) in the same or different molecule
hydration
water molecules surround polar molecules and ions shielding off their charges and ensuring that they remain in the solution
homeostasis
maintenance of the relativ internal stability by physiological control systems
hematocrit
percentage of total blood volume occupied by (mostly red) blood cells, in humans it is normally between 40-50%
GTP
guanosine triphosphate, energy-rich nucleotide, like ATP
Goldman-Hodgkin-Katz equation
approximate description of the resting membrane potential, based on the concentration and permeability of the three most important diffusible ions (Ka+, K+, CI-)
glycoprotein
a protein containing carbohydrate groups
glycolipid
a lipid containing carbohydrate groups, in most cases galactose
glycogen
highly branched glucose polymer found in animals (“animal starch”)
glucose
aldohexose, the cell’s primary metabolic fuel; blood sugar
globulin
A type of blood plasma protein molecule that has a spherical tertiary structure (e.g. hemoglobin, immunoglobulin)
functional syncytium
heart mucle cells, in contrast to skeletal muscle cells do not fuse to form fibres, but form a functional unit because of the electrical synapses (gap juntions) between them
functional residual capacity
(FRC) volume of air remaining in the lungs at the end of a normal expiration
Fructose
ketohexose found in honey and many fruits
- type of monosaccharide carbohydrate; a simple sugar molecule
Fluid mosaic model
according to this model, biological membranes are built up of a lipid bilayer in which protein molecules can easily move (float) in the horizontal direction
filtration
movement of water and small molecules through a membrane (capillary wall) because of the pressure difference
filament
thin fiber made up of proteins; sliding of actin and myosin filaments on each other explains muscle contraction
fibrinogen
protein component of the blood plasma; its polymerization to fibrin is the most important step of blood coagulation
fibrillation
asynchronous, disorganised contraction of individual muscle fibres in the atria or ventricles of the heart
FAD
flavin - adenin dinucleotid, coenzyme
facilitation
temporal increase of synaptic efficacy due to preceding activation of that synapse
facilitated diffusion
passive transport of a molecule across a membrane along the concentration gradient, thus not using energy, but requiring a transporter to help the passage of the molecule
extrasystole
excitation and contraction of the heart not corresponding to the normal sinus rythm
A premature contraction of the heart that is independent of the normal rhythm of the heart and that arises in response to an impulse in some part of the heart other than the normal impulse from the sinoatrial (SA) node.
- The extrasystole is followed by a pause, as the heart electrical system “resets” itself and the contraction following the pause is usually more forceful than normal. These more forceful contractions are frequently perceived as palpitations.
expirational reserve volume
(ERV) volume exhaled by an active expiratory effort at the end of a passive tidal expiration
exocytosis
transport of substances stored in internal vesicles from the cell to the surroundings by fusion of the vesicle with the cell membrane
-durable, energy-consuming process by which a cell directs the contents of secretory vesicles out of the cell membrane and into the extracellular space.
Evans blue
blue stain that cannot penetrate the capillary wall; used for measuring the blood volume
eupnea
normal breathing
equilibrium
lowest energy state of a system that may result from opposing forces arising from within the system
eosinophil granulocyte
white blood cell containing vesicles stained by eosin (acidic stain)
endothelium
single cell layer forming the internal lining of blood vessels
endocytosis
entrance of substances into the cell by membrane invagination to form an internal vesicle
endocrine communication
the signal (e.g. hormone) uses the bloodstream as a channel to reach the target cells
emolism
blockade of a vessel by an air bubble or blood clot originating at a different part of the circulatory system
elimination
blockade of a vessel by an air bubble or blood clot originating at a different part of the circulatory system
electrotonic transmission
decremental transmission: electrical signal transmission in which signals are conducted with exponentially decreasing amplitude in space
Electrotonic potential: represent changes to the neuron’s membrane potential that do not lead to the generation of new current by action potential
decremental transmission
electrical signal transmission in which signals are conducted with exponentially decreasing amplitude in space
electrostatic interaction
attraction between oppositely charged ions or parts of larger molecules
electronegativity
dimensionless number indicating the affinity (tilhørighet/belonging) of atoms of a given element to the electrones
electrochemical potential
combined effect of the electrical and concentration gradients on an ion
electrical synapse
alternate name for gap junctions between excitable cells through which small molecules, thus ions carrying excitation can pass
Einthoven leads
standard way of electrode positioning for recording ECG in humans
effector protein
protein transmitting the effect of G-protein activation in the cell
edema
accumulation of fluid in the interstitial space
dyspnea
labored, difficult breathin
dorsal root ganglion
collection of somata of primary sensory neurons on the nerve trunk entering the spinal cord on the doorsal surface
Donnan Equilibrium
electrochemical equilibrium that develops when two solutions are sparated by a membrane permeable to only some of the ions in the solutions
disulfide linkage
a bond between two sulfide groups (side chains of cystein amino acids) determining the structure of proteins
disaccharides
double sugar molecule formed by two single sugars
- type og carbohydrate
- e.g. sucrose made up of glucose and fructose
dipole
a molecule having separate regions of net negative and net positive charge
diffusion
random thermal movement of atoms, molecules and ions from sites with higher concentration toward sites with lower concentration
diastole
the phase in the heartbeat during which the myocardium is relaxed and the ventricles are filling with blood
- happens after repolarization
diaphragm
dome-shaped muscle separating the thoracic and abdominal cavities in mammals
depressor area (center)
collection of neurons located caudally in medially from the pressor area in the medulla decreasing blood pressure by the inhibition of the pressor area and by excitation of the vagal efferents running to the heart
depolarization
sudden change within a cell during which the cell undergoes a dramatic electrical change
- see hypopolarization: a shift of the resting membrane potential toward less negative values - a decrease
dendrite
fine process of a neuron that typically provide the main receptive area for synaptic inputs from other neurons
denaturation
usually irreversible change in the conformation of protein molecules
covalent bond
the strongest bond between two atoms in which electrons are shared on common molecular orbits
convection
bulk flow, movement of substances caused by pressure differences
contractility
ability for shortening
- in case of myocardial contractility: the intrinsic ability of the heart/myocardium to contract
conformational change
transient, reversible change in the spatial structure of a protein molecule
conductance
reciprocal value of the resistance
May refer to:
- Electrical conductance, the ability for electricity to flow a certain path
- Fluid conductance, the ability for fluid to transmit through materials
- Thermal conductivity, the ability for temperatures to transmit through materials
concentration gradient
change in the concentration of a substance depending on distance (dc/dx)
- a gradual change in the concentration of solutes in a solution as a function of distance through a solution.
- the gradual difference in the concentration of solutes in a solution between two regions.
- In biology, a gradient results from an unequal distribution of ions across the cell membrane. When this happens, solutes move along a concentration gradient. This kind of movement is called diffusion.
complement system
protein molecules responsible for the elimination of the antigen-antibody complex
competitive inhibition
reversible inhibition caused by a molecule that can bind to the same active site of an enzyme, receptor or transporter as the inhibited molecule
compensatory pause
longer than normal pause between two heart beats following and extrasystole
- The extrasystole is followed by a pause, as the heart electrical system “resets” itself and the contraction following the pause is usually more forceful than normal. These more forceful contractions are frequently perceived as palpitations.
compartmentalization
division of a space (e.g. cytoplasm) with limiting surfaces into subspaces with limited exchange of materials
colocalization
simultaneous presence of two transmitters or a transmitter and a neuromodulator in the same synaptic vesicle
colloid osmotic pressure
osmotic pressure generated by blood proteins unable to penetrate through the capillary wall
Osmotic pressure:
the pressure necessary to prevent osmosis into a given solution when the solution is separated from the pure solvent by a semipermeable membrane
collateral processes
branches of an axon terminating in locations other than the major target location
collagen
protein, main component of the collagen fibres
CoA, coenzyme A
coenzyme built around the adenine nucleotide
cis and trans position
on the same or on the opposite side
cis means on this side
trans means on the other side
- e.g. the two possibilities for the continuation of the lipid chain at the two ends of a double bond in an unsaturated fatty acid
choroid plexus
glomeruli of blood vessels protruding into the brain ventricles and covered by glial cells whose function is the secretion of liquor (cerebrospinal fluid, CSF)
cellulose
polysaccharide built up of glucose molecules forming straight chains
catecholamines
biogenic amines based on the catechol structure
aromatic six-carbon ring with two OH groups:
- dopamine (DA),
- norepinephrine (noradrenalin, NA),
- epinephrine (adrenaline, Adr)
carotid sinus
dilatation of the internal carotid artery at its origin, containing many baroreceptors
capacitance vessels
alternate name for veins because of their large compliance
capacitance of blood vessels:
- describes the distensibility of blood vessels located within the body; it is directly related to elasticity.
- Therefore, the greater the amount of elastic tissue in a blood vessel, the greater the elasticity, and the lower the compliance.
- This ultimately describes how volume changes in response to a change in pressure within the blood vessel at hand.
cAMP
cyclic adenosine monophosphate, signaling molecule
bundle of His
- special conducting tract within the interventricular septum of the mammalian heart
- running from the atrioventricular (AV) node toward the poles of the ventricles
bronchiole
part of the airways containing no cartilage
the passageways by which air passes through the nose or mouth to the alveoli (air sacs) of the lungs, in which branches no longer contain cartilage or glands in their submucosa.
blood-brain-barrier
mechanism controlling the transport of materials from the blood to the extracellular space of the brain
- highly selective permeability barrier that separates the circulating blood from the brain extracellular fluid (BECF) in the central nervous system (CNS).
bipolar neuron
neuron with two processes fulfilling the same function
- specialized sensory neurons for the transmission of special senses. As such, they are part of the sensory pathways for smell, sight, taste, hearing and vestibular functions.
- Common examples are the bipolar cell of the retina, the ganglia of the vestibulocochlear nerve,[1] and the extensive use of bipolar cells to transmit efferent (motor) signals to control muscles.
biogenic amines
signalling molecules synthesized in the body from amino acids by decarboxylization
bilirubin
end product of heme metabolism during the normal destruction of red blood cells
beta sheet
two-dimensional secondary structure of proteins stabilised by H-bonds between peptide bonds on chain segments running in the opposite directions
basophil granulocyte
white blood cell containing vesicles stained by basic stains
basal myogenic tone
in some parts of the body, vessels with a muscular wall (mostly arterioles) contract in response to an increase in blood pressure to prevent an unnecessary increase in blood flow
baroreceptor reflex
reflex mechanism starting from baroreceptors in the carotid sinus and in the aortic arch which regulate blood pressure
the baroreceptors are stretched more the higher the blood pressure is, thus sending signals to the control centers which then decrease or increase the blood pressure depending on the signal.
axonal transport (anterograde, retrograde)
- transport mechanism in neurons providing relatively fast movement of substances toward the axon terminals (forward) and toward the cell body (retrograde)
axon
neurit, a process of neurons specialized for the transmission of excitation
autoimmune disease
erroneous immune response of an organism against its own proteins or macromolecules
atrium
chamber of the heart into which venous blood is returned
left atrium
right atrium: containing sinotrial (SA) node
atrioventricular node
specialized conduction tissue in the heart at the border of the right atrium and ventricle
ATP
adenosine-triphosphate, energy-rich nucleotide used as a common energy source by all cells
arteriovenous oxygen difference
difference between the partial pressure of oxygen in the arterial and venous blood flowing to and from an organ
arteriovenous anastomosis
short vessels found especially in the skin, connecting arterioles and venules
arteriole
muscular vessel connecting arteries and capillaries
- type of muscular artery
- smooth muscles that are in the wall of the artery make the venule very tight, which increases its resistance
apnea
a suspension or absence of breathing
antigen
usually a large molecule or a smaller part of it that induces immunological response in the target organism
- in the surface of the blood plasma
antagonist
a substance that inhibits the effect of a mediator or transmitter at the receptor
annulus fibrous
sheet of connective tissue separating the atria from ventricles and providing anchoring points for the valves
anisotropic substance
differentially transparent to polarized light depending on the plane of the light
alveoli
functional units of the lung, gases are exchanged through the walls of the alveoli
alpha helix
helical secondary structure of proteins spabilized by H-bonds between peptide bonds located above each other
alpha carbon atom
in organic acids the C-atom closest to the carboxyl group
see alpha amino acids
all-or-none response
amplitude of action potentials induced in excitable cells does not depend on the strength of the stimulus only on the membrane properties and on the ionic gradients
aldo-sugar
sugar containing a aldehyde group (e.g. glucose, galactose)
albumin
largest protein fraction in the blood plasma, mainly responsible for the colloid osmotic pressure of the plasma
agonist
a substance that have the same effect on a receptor as the mediator or transmitter
afterhyperpolarization
hyperpolarization following an action potential
acive transport
energy- requiring translocation of a substance across a membrane against its electrochemical gradient
actin and myosin
proteins responsible for the muscle contraction
granylocyte
white blood cells with multilobed nuclei and cytoplasmic graules whose staining is used to differentiate between the three basic types: neutrophil, basophil and eosinophil
