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Flashcards in S-words Deck (27):
1

saltatory conduction

the propagation of APs from myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of APs

2

sarcolemma

membrane of the muscle fiber

3

sarcomere

basic unit of striated muscle tissue

4

sarcoplasm

cytoplasm of the muscle fiber

5

sarcoplasmic reticulum

similar to the smooth endoplasmic reticulum, the sarcoplasmic reticulum stores calcium ions and pumps them out into the sarcoplasm when the muscle fiber is stimulated

6

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

7

Schwann cell

glia cell forming the myelin sheath around the periphery (external surface) of axons

8

second messengers

small molecules whose concentration changes after the first messenger attaches to the membrane receptor

9

secondary structure of proteins

regular structures of peptide chains stabilized by hydrogen bonds (alpha helix, beta sheet)

10

semilunar valves

valves at the opening of the aorta and pulmonary artery

11

semipermeable membrane

membrane separating two solutions, permeable to only some of the solvents

12

septum

muscular tissue separating the left and right atria and ventricle

13

side chain

a group bond to the carbon atom of amino acids

14

sinoatrial node

specialized cardiac tissue in the right atrium acting as the pacemaker of the heart

15

sliding filament hypothesis

theory explaining muscle contraction by the sliding of actin and myosin filaments on each other

16

space constant

externally induced and electronically conducted potential changes in the membrane decrease to 37% after traveling a distance equal to the space constant

17

specificity

due to its spatial structure, a receptor, enzyme or transporter molecule can only bind a limited number of substrate molecules

18

spirometer

device used to measure lung volumes and aspects of breathing

19

Starling's hypothesis

theory used to explain the production and absorption of interstitial fluid

20

strength (energy) of a bond

energy released during the formation of the given bonds between atoms, which is needed to break apart the atoms

21

sucrose

built up of glucose and fructose, most common commercially available sweetener

22

summation

adding up the effects of two synaptic potentials occurring at the same synapse with short delay, or in neighboring synapses concurrently

23

surface active agent

amphipathic molecule bearing both hydrophilic and hydrophobic groups

24

surface active substance

its molecules possess both hydrophilic and hydrophobic parts and they tend to line up at the border separating two different phases with the hydrophilic and hydrophobic parts located in the appropriate phase

25

surfactant

surface active agent lining the inner surface of the alveoli and decreasing surface tension

26

saturation

characteristic feature of protein mediated transport processes – if the concentration of the molecules to be transported increases, the speed of the transport decreases, as most of the transporter molecules tend to be occupied after a certain concentration

27

systole

the part of the cardiac cycle when the heart contracts