Test 1- vocab Flashcards
1
Q
pathophysiology
A
study of the function of body parts
2
Q
physiology
A
study of disease states
3
Q
basement membrane
A
extracellular protein layer that epithelial cells rest on
anchors the tissue
4
Q
cell differentiation
A
the process of transforming an unspecialized cell into a specialized cell
formation of 4 general types of cells
- muscle cells (skeletal, cardiac, and smooth muscle)
- neurons
- epithelial cells
- connective tissue cells
5
Q
cells
A
simplest structural units into which a complex multicellular organism can be divided and still retain the functions characteristic of life
6
Q
collagen fibers
A
rope like fibers
7
Q
connective tissue
A
one of the four major categories of tissues in the body
major component of extracellular matrices, cartilage, and bone
8
Q
connective tissue cells
A
connect, anchor, and support the structures of the body
9
Q
elastin fibers
A
proteins with elastic or springlike properties; found in large arteries and in the airways
10
Q
epithelial cells
A
cells at surface of body or hollow organ; specialized to secrete or absorb ions and organic molecules; with other epithelial cells form an epithelium
11
Q
epithelial tissues
A
one of the four major tissue types in the body, comprised of aggregates epithelial cells
12
Q
epithelium
A
tissue that covers all body surfaces, lines all body cavities, and forms most glands
13
Q
extracellular matrix (ECM)
A
a complex consisting of a mixture of proteins interspersed with extracellular fluid
14
Q
fibers
A
15
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functional units
A
small structures within an organ that acts similarly to carry out an organ’s function
16
Q
muscle cells
A
specialized cells containing actin and myosin filaments and capable of generating force and movement
17
Q
muscle tissue
A
one of the four major tissue types in the body, comprising smooth, cardiac, and skeletal muscle; can be under voluntary or involuntary control
18
Q
nerve
A
group of many axons from numerous neurons, encased in connective tissue and traveling together in peripheral nervous system
19
Q
nervous tissue
A
one of the four major tissue types in the body, responsible for coordinated control of muscle activity, reflexes, and conscious thought
20
Q
neuron
A
cell in nervous system specialized to initiate, integrate, and conduct electrical signals
21
Q
organs
A
collections of tissues joined in structural units to serve common function
22
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organ system
A
organs that together serve an overall function
23
Q
tissues
A
aggregates of single type of specialized cell; also denote general cellular fabric of a given organ
24
Q
extracellular fluid
A
fluid outside cell
composed of:
25
internal environment
extracellular fluid (interstitial fluid and plasma)
26
interstitial fluid
extracellular fluid surrounding tissue cells, excludes plasma
27
interstitium
interstitial space; fluid-filled space between tissue cells
28
intracellular fluid
fluid in cells; cytosol plus fluid in cell organelles
composed of
29
plasma
liquid component of blood; component of extracellular fluid
30
dynamic constancy
a way of describing homeostasis that includes the idea that a variable may vary in the short term but is stable and predictable when averaged over the long term
31
homeostasis
relatively stable condition of internal environment that results from regulatory system actions
32
equilibrium
no net change occurs in a system; requires no energy
33
feedforward regulation
34
homeostatic control systems
collections of interconnected components that keep a physical or chemical variable internal environment within predetermined normal ranges of values
35
negative feedback
characteristic of control systems in which system's response opposes the original change in the system
36
positive feedback
a characteristic of control systems in which an initial disturbance sets off train of events that increase the disturbance even further
37
set point
steady-state value maintained by homeostatic control sytstem
38
steady state
no net change; continual energy input to system is required however, to prevent net change
39
acquired reflexes
behaviors that appear to be stereotypical and automatic but that in fact result from considerable conscious effort to be learned
40
afferent pathway
component of reflex arc that transmits information from receptor to integrating center
41
effector
cell or cell collection whose change in activity constitutes the response in a control system
42
efferent pathway
component of reflex arc that transmits information from integrating center to effector
43
hormone
chemical messenger synthesized by specific endocrine cells in response to certain stimuli and secreted into the blood which carries it to target cells
44
integrating center
brain region that compares the actual value of a variable such as body temperature to a set point
45
learned reflexes
same as acquired reflexes
46
local homeostatic responses
responses acting in immediate vicinity of a stimulus, without nerves or hormones, and having net effect of counteracting stimulus, without nerves or hormones, and having net effect of counteracting stimulus
47
receptor
for messengers: protein either on cell surface, in the cytosol, or in the nucleus that binds a chemical messenger such as a hormone or neurotransmitter and mediates its actions
in sensory system: specialized peripheral ending of afferent neuron, or separate cell intimately associated with it, that detects changes in some aspect of environment
48
reflex
biological control system linking stimulus with response and mediated by a reflex arc
49
reflex arc
neural or hormonal components that mediate a reflex; usually includes receptor, afferent pathway, integrating center, efferent pathway, and effector
50
stimulus
detectable change in internal or external environment
51
autocrine substances
chemical messengers secreted into extracellular fluid that act upon the cell that secreted them
52
endocrine glands
group of epithelial cells that secrete into the extracellular space hormones that then diffuse into the blood stream
53
neurotransmitters
chemical messengers used by neurons to communicate with each other or with effectors
54
paracrine substances
chemical messengers that exert their effects on cells near their secretion sites; by convention, exclude neurotransmitters
55
acclimatization
environmentally induced improvement in functioning of a physiological system with no change in genetic endowment
56
adaptation
evolution: a biological characteristic that favors survival in a particular environment
neural: decrease in action potential frequency in a neuron despite constant stimulus
57
circadian rhythm
occurring in an approximately 24 hour cycle
58
entrainment
adjusting biological rhythm to environmental cues
59
free-running rhythm
cyclical activity driven by biological clock in absence of environmental cues
60
melatonin
an amine derived from tryptophan produced in the pineal gland and that plays a role in circadian rhythms
61
negative balance
loss of substance from body exceeds gain, and total amount in body decreases; also used for physical parameters such as body temperature and energy
62
pacemaker
neurons that set rhythm of biological clocks independent of external cues; any neuron or muscle cell that has an inherent autorhythmicity and determines activity pattern of other cells
63
pineal gland
part of the epithalamus of the brain; produces melatonin involved in circadian rhythyms
64
pool
the readily available quanityt of a substance in the body; often equal amounts in extracellular fluid
65
positive balance
gain of substance exceeds loss, and amount of that substance in body increases
66
stable balance
net loss of substance from body equals net gain, and amount of substance in body neither increases nor decreases
67
cell organelles
membrance-bound compartments, nonmembranous particles, or filaments that perform specialized functions in cell
68
cytoplasm
region of cell interior outside nucleus
69
cytosol
intracellular fluid that surrounds cell organelles and nucleus
70
nucleus
cell: large membrane-bound organelle that contains cells DNA
neural: cluster of neuron cell bodies CNS
71
plasma membrane
membrane that forms outer surface of cell and separates cell's contents from extracellular fluid
72
cadherins
proteins that extend from a cell surface and link up with cadherins from other cells; important in the formation of tissues
73
desmosomes
junctions that hold two cells together; consist of plasma membranes of adjacent cells linked by fibers, yet separated by a 20 nm extracellular space filled with a cementing substance
74
fluid-mosaic model
cell membrane structure consists of proteins embedded in bimolecular lipid that has the physical properties of a fluid, allowing membrane proteins to move laterally within it
75
gap junction
protein channels linking cytosol of adjacent cells; allows ions and small molecules to flow between cytosols of the connected cells
76
integral membrane proteins
Proteins embedded in membrane lipid layer; may span entire membrane or be located at only one side
77
integrins
Transmembrane proteins in plasma membrane; bind to specific proteins in extracellular matrix and on adjacent cells to help organize cells into tissues
78
peripheral membrane proteins
hydrophilic proteins associated with cytoplasmic surface of cell membrane
79
phospholipids
lipid subclass similar to triglycerides except that a phosphate moiety and small nitrogen-containing molecule are attached to third hydroxyl group of glycerol; major components of cell membranes
80
tight junction
cell junction in which extracellular surfaces of the plasma membrane of two adjacent cells are joined together; extends around epithelial cell and restricts molecule diffusion through space between cells
81
transmembrane protein
proteins that span the plasma membrane and contain both hydrophilic and hydrophobic regions; often act as receptors or ion channels
82
actin filaments
polymers of G-actin that form part of the cell cytoskeleton and are part of the contractile apparatus of the muscle cells
83
adenosine triphosphate (ATP)
nucleotide that transfers energy from metabolism to cell functions during it breakdown to ADP and release of Pi
84
centrioles
small cytoplasmic bodies, each having nine fused sets of microtubules; participate in nuclear and cell division
85
centrosome
region of cell cytoplasmic bodies, each having nine fused sets of microtubules; participate in nuclear and cell division
86
chromatin
combination of DNA and nuclear proteins; principal component of chromosomes
87
chromosomes
strands of DNA formed from condensed chromatin, containing all the genes that for the proteins found in the body
88
cilia
hairlike projections from specialized epithelial cells that sweep back and forth in a synchronized way to propel material along epithelial surface
89
ciliopathies
what diseases associated with mutated genes expressed in cilia in different tissues. These occur most frequently in the retina, liver, kidneys, and brain
90
cristae
the inner membrane of mitochondria, which may assume sheetlike or tubular appearances; site containing cytochrome P450 enzymes involved in steroid hormone production
91
cytoskeleton
cytoplasmic filamentous network associated with cell shape and movement
92
endoplasmic reticulum
cell organelle that consists of interconnected network of membrane-bound branched tubules and flattened sacs; two types are distinguished: rough, with ribosomes attached, and smooth, which is smooth-surfaced (does not contain ribosomes)
93
endosomes
94
golgi apparatus
intracellular vesicles that transport molecules between golgi apparatus, lysosomes, and plasma membrane
95
intermediate filaments
actin containing filaments associated with desmosomes
96
lysosomes
membrane-bound cell organelles containing digestive enzymes in a highly acidic solution that breaks down bacteria, large molecules that have entered the cell, and damaged components of the cell
97
matrix
mitochondrial: the innermost mitochondrial compartment
98
microtubules
tubular cytoplasmic filaments composed of the protein tubulin; provide internal support for cells and allow change in cell shape and organelle movement in cell
99
mitochondria
rod-shaped or oval cytoplasmic organelles that produce most of cell's ATP; sites of Krebs cycle and oxidative-phosphorylation enzymes
100
nuclear envelope
double membrane surrounding cell nucleus
101
nuclear pores
openings in nuclear envelope through which molecular messengers pass between nucleus and cytoplasm
102
nucleolus
densely staining nuclear region containing portions of DNA that code for ribosomal proteins
103
peroxisomes
cell organelles that destroy certain toxic products by oxidative reactions
104
ribosomes
cytoplasmic particles that mediate linking together of amino acids to form proteins; attached to endoplasmic reticulum as bound ribosomes, or suspended in cytoplasm as free ribosomes
105
secretory vesicles
membrane-bound vesicles produced by Golgi apparatus; contain protein to be secreted by cell
106
tubulin
the major protein component of microtubules
107
gene
unit of hereditary information; portion of DNA containing information required to determine a protein's amino acid sequence
108
genome
complete set of an organism's genes
109
histones
class of proteins that participate in the packaging of DNA within the nucleus; strands of DNA form coils around the histones
110
nucleosomes
nuclear complexes of several histones and their associated coils of DNA
111
stop signals
three-nucleotide sequences in mRNA that signify end of protein-coding sequence
112
trancsription
formation of RNA containing, in linear sequence of its nucleotides, the genetic information of a specific gene; first stage of protein synthesis
113
translation
during protein synthesis, assembly of amino acids in correct order according to genetic instructions in mRNA; occurs on ribosomes
114
anticodon
three-nucleotide sequence in tRNA able to base-pair with complementary codon in mRNA during protein synthesis
115
codon
three-base sequence in mRNA that determines the position of specific amino acid during protein synthesis or that designates the end of the coded sequence of a protein
116
exons
DNA gene regions containing code words for a part of the amino acid sequence of a protein
117
initiation factors
proteins required for ribosomal assembly and the establishment of an initiation complex that allows new protein synthesis to begin
118
introns
regions of noncoding nucleotides in a gene
119
mRNA
ribonucleic acid that transfers genetic information for a protein's amino acid sequence from DNA to ribosome
120
mutagens
factors in the environments that increase mutation rate
121
mutation
any change in base sequence of DNA that changes genetic information
122
natural selection
the process whereby mutations in a gene lead to traits that favor survival of an organism
123
preinitiation complex
a group of transcription factors and accessory proteins that associate with promoter regions of specific genes; the complex is required for gene transcription to commence
124
pre mRNA
an RNA molecule transcribed from a gene before intron removal and splicing
125
promoter
specific nucleotide sequence at beginning of gene that control the initiation of gene transcription; determines which of the paired strands of DNA is transcribed into RNA
126
proteome
all of the proteins expressed by a particular cell at a given time
127
rRNA
ribosomal RNA; type of RNA used in ribosome assembly; becomes part of ribosome
128
RNA polymerase
enzyme that forms RNA by joining together appropriate nucleotides after they have base paired to DNA
129
splicesome
protein and nuclear RNA complex that removes introns and links exons together during gene transcription
130
template strand
the DNA strand with the correct orientation relative to a promoter to bind RNA polymerase
131
transcription factors
proteins that act as gene switches, regulating the transcription of a particular gene by activating or repressing the initiation process
132
tRNA
transfer RNA; different tRNAs combine with different amino acids and with codon on mRNA specific for that amino acid, thus arranging amino acids in sequence to form specific protein
133
proteasome
a complex of proteins capable of denaturing (unfolding) other proteins and assisting in protein degradation
134
ubiquitin
small intracellular peptide that attaches to proteins and directs them to proteasomes
135
signal sequence
initial portion of newly synthesized protein (if protein is destined for secretion)
136
affinity
strength with which ligand binds to its binding site
137
binding site
region of protein to which a specific ligand binds
138
chemical specificity
selectivity; ability of binding site to react with only one, or a limited number, of chemicals
139
competition
ability of similar molecules to combine with the same binding site or receptor
140
ligand
any molecule or ion that binds to protein surface by noncovalent bonds
141
saturation
occupation of all available binding sites by their ligand
142
allosteric modulation
in the case of a protein with binding sites for two different ligands, the binding of one ligand alters the binding characteristics of the protein for the other ligand
143
allosteric proteins
proteins whose binding site characteristics are subject allosteric modulation
144
cooperativity
interaction between functional binding sites in a multimeric protein
145
covalent modulation
alteration of a protein's shape, and therefore its function, by the covalent binding of various chemical groups to it
146
functional site
binding site on allosteric protein that, when activated, carries out protein's physiological function; also called the active site
147
modulator molecule
ligand that, by acting at an allosteric regulatory site, alters properties of other other binding sites on a protein and thus regulates its functional activity
148
phosphoprotein phosphatases
enzymes that remove phosphate from protein
149
phosphorylation
addition of phosphate group to an organic molecule
150
protein kinase
any enzyme that phosphorylates other proteins by transferring them a phosphate group from ATP
151
regulatory site
site on protein that interacts with modulator molecule; alters functional site properties
152
activation energy
energy necessary to disrupt existing chemical bonds during a chemical reaction
153
anabolism
cellular synthesis of organic molecules
154
calorie
unit of heat-energy measurement; amount of heat needed to raise temperature of 1 g of water 1 C
155
catabolism
cellular breakdown of organic molecules
156
catalyst
substance that accelerates chemical reactions but does not itself undergo any net chemical change during the reaction
157
chemical equilibrium
state when rates of forward and reverse components of a chemical reaction are equal, and no net change in reactant or product concentration occurs
158
irreversible reactions
chemical reactions that release large quantities of energy and result in almost all the reactant molecules being converted to product
159
kilocalories
1 kcal is the amount of heat energy required to raise the temperature of 1 kg water by 1 C
160
law of mass action
maxin that an increase in reactant concentration causes a chemical reaction to proceed in direction of product formation; the opposite occurs with decreased reactant concentration
161
metabolism
chemical reactions that occur in a living organism
162
reversible reaction
chemical reaction in which energy release is small enough for reverse reaction to occur readily
163
active site
region of enzyme to which substrate binds
164
coenzyme
organic cofactor; generally serves as a carrier that transfers atoms of small molecular fragments form one reaction to another; is not consumed in the reaction and can be reused
165
cofactors
organic or inorganic substances that bind to a specific region of an enzyme and are necessary for the enzyme's activity
166
enzymes
protein catalysts that accelerate specific chemical reactions but do not themselves undergo net chemical change during the reaction
167
FAD
flavin adenine dinucleotide, a coenzyme derived from the B-vitamin riboflavin that participates in transfer of hydrogen atoms during metabolism
168
NAD+
nicotinamide adenine dinucleotide; formed from the B-vitamin niacin and involved in transfer of hydrogens during metabolism
169
substrates
reactants in enzyme-mediated reaction
170
vitamins
organic molecules required in trace amounts for normal health and growth; usually not manufactured in the body and must be supplied by diet; classified as water-soluble and fat-soluble
171
enzyme activity
rate at which enzyme converts reactant to product; may be measure of the properties of enzyme's active site as altered by allosteric or covalent modulation; affects rate of enzyme-mediated reaction
172
end-product inhibition
inhibition of a metabolic pathway by final product's action upon allosteric site on an enzyme (usually the rate-limiting enzyme) in the pathway
173
metabolic pathway
sequence of enzyme-mediated chemical reactions by which molecules are synthesized and broken down in cells
174
rate-limiting reaction
slowest reaction in metabolic pathway; catalyzed by rate-limiting enzyme
175
acetyl CoA
acetyl coenzyme A; metabolic intermediate that transfers acetyl groups to krebs cycle and various synthetic pathways
176
ATP synthase
the enzyme complex present in mitochondria responsible for the synthesis of ATP using the energy of an electrochemical gradient for hydrogen ions
177
chemiosmosis
the mechanism by which ATP is formed during oxidative phosphorylation; the movement of protons across mitochondrial inner membranes is coupled with ATP production
178
citric acid cycle
mitochondrial metabolic pathway that utilizes fragments derived from carbohydrate, protein, and fat breakdown and produces carbon dioxide, hydrogen (for oxidative phosphorylation), and small amounts of ATP
179
cytochromes
enzymes that couple energy to ATP formation during oxidative phosphorylation
180
electron-transport chain
a series of metal-containing proteins within mitochondria that participate in the flow of electrons from proteins to molecular oxygen; they are key components of the energy-producing process in all cells
181
glycolysis
metabolic pathway that breaks down glucose to pyruvate or lactate
182
Krebs cycle
mitochondrial metabolic pathway that utilizes fragments derived from carbohydrate, protein, and fat breakdown and produces carbon dioxide, hydrogen (for oxidative phosphorylation), and small amounts of ATP
183
lactate
ionized form of lactic acid, a three-carbon molecule formed by glycolytic pathway; production is increased in absence of oxygen
184
oxidative phosphorylation
process by which energy derived from reaction between hydrogen and oxygen to form water is transferred to ATP during its formation
185
pyruvate
anion formed when pyruvic acid loses a hydrogen ion
186
substrate-level phosphorylation
direct transfer of phosphate group from metabolic intermediate to ADP to form ATP
187
tricarboxylic acid cycle
mitochondrial metabolic pathway that utilizes fragments derived from carbohydrate, protein, and fat breakdown and produces carbon dioxide, hydrogen (for oxidative phosphorylation), and small amounts of ATP
188
adipocytes
cells specialized for triglyceride synthesis and storage; fat cells
189
adipose tissue
tissue composed largely of fat-storing cells
190
beta oxidation
series of reactions that generate hydrogen atoms (for oxidative phosphorylation) from breakdown of fatty acids to acetyl CoA
191
essential amino acids
amino acids that cannot be formed by the body at all (or at a rate adequate to meet metabolic requirements) and so must be obtained from diet
192
gluconeogenesis
formation of glucose by the liver or kidneys from pyruvate, lactate, glycerol, or amino acids
193
glycerol 3-phosphate
three-carbon molecule that combines with fatty acids to form triglyceride
194
glycogen
highly branched polysaccharide composed of glucose subunits; major carbohydrate storage form in body
195
glycogenolysis
glycogen breakdown to glucose
196
keto acid
a class of breakdown products formed from the deamination of amino acids
197
negative nitrogen balance
net loss of amino acids in the body over any period of time
198
oxidative deamination
reaction in which an amino group (NH2) from an amino acid is replaced by oxygen to form a keto acid
199
positive nitrogen balance
a period in which there is net gain of nitrogen (amino acids) in the body
200
proteases
enzymes capable of breaking peptide bonds in a protein
201
proteolysis
the process whereby peptides and proteins are cleaved into smaller molecules, by the actions of specific enzymes (proteases)
202
transamination
reaction in which an amino acid amino group (NH2) is transferred to a keto acid, the keto acid thus becoming an amino acid
203
urea
major nitrogenous waste product of protein breakdown
204
essential nutrients
substances required for normal or optimal body function but synthesized by the body either not at all or in amounts inadequate to prevent disease
205
fat-soluble vitamins
K, A, D, E
206
water soluble vitamins
C and B complex
207
channel gating
process of opening and closing ion channels
208
diffusion equilibrium
state during which diffusion fluxes in opposite directions are equal; that is, the net flux equals zero
209
electrochemical gradient
the driving force across a plasma membrane that dictates whether an ion will move into or out of a cell; established by both the concentration difference and the electrical charge difference between the cytosolic and extracellular surfaces of the membrane
210
Fick's law of diffusion
describes the rate of diffusion of a solute as a function of concentration gradient, area across which the solute diffuses, and other factors
211
flux
rate of flow of a substance (such as a solute in water) through a unit of surface area in a unit of time
212
ion channels
small passages in plasma membrane formed by integral membrane proteins and through which certain small-diameter molecules and ions can diffuse
213
ligand-gated ion channels
membrane ion channels operated by the binding of specific molecules to channel proteins
214
membrane potential
voltage difference between inside and outside of cell
215
net flux
difference between two one-way fluxes
216
simple diffusion
movement of solutes down a concentration gradient without a transporter or ATP hydrolysis
217
voltage-gated ion channels
channels cell membrane ion channels opened or closed by changes in membrane potential
218
active transport
energy-requiring system that uses transporters to move ions or molecules across a membrane against an electrochemical difference
219
cotransport
form of secondary active transport in which net movement of actively transported substance and "downhill" movement of molecule supplying the energy are in the same direction
220
countertransport
form of secondary active transport in which net movement of actively transported molecule is in direction opposite "downhill" movement of molecule supplying the energy
221
facilitated diffusion
system using a transporter to move molecules from high to low concentration across a membrane; energy not required
222
mediated transport
movement of molecules across membrane by binding to protein transporter; characterized by specificity, competition, and saturation; includes facilitated diffusion and active transport
223
Na+/K+ ATPase pump
primary active-transport protein that hydrolyzes ATP and releases energy uses to transport sodium ions out of cell and potassium ions in
224
primary active transport
active transport in which chemical energy is transferred directly form ATP to transporter protein
225
secondary active transport
active transport in which energy released during transmembrane movement of one substance from higher to lower concentration is transferred to the simultaneous movement of another substance from lower to higher concentration
226
transporters
integral membrane proteins that mediate passage of molecules through membrane
227
aquaporins
protein membrane channels through which water can diffuse
228
hyperosmotic
having total solute concentration greater than normal extracellular fluid
229
hypoosmotic
having total solute concentration less than that of normal extracellular fluid
230
hypotonic
solutions containing a lower concentration of effectively nonpenetrating solute particles than normal (isotonic) extracellular fluid
231
isoosmotic
having the same total solute concentration as extracellular fluid
232
isotonic
containing the same number of effectively nonpenetrating solute particles as normal extracellular fluid
233
nonpenetrating solutes
dissolved substances that do not passively diffuse across a plasma membrane
234
osmol
1 mole of solute ions and molecules
235
osmolarity
total solute concentration of a solution; measure of water in that the higher the solution osmolarity, the lower the water concentration
236
osmosis
net diffusion of water across a selective barrier from region of higher water concentration (lower solute concentration) to region of lower water concentration (higher solute concentration)
237
osmotic pressure
pressure that must be applied to a solution on one side of a membrane to prevent osmotic flow of water across the membrane from a compartment of pure water; a measure of the solution's osmolarity
238
penetrating solutes
solute that can freely diffuse across the lipid bilayer of a plasma membrane
239
semipermeable membrane
membrane permeable to some substances (usually water) but not to others (some solutes)
240
clathrin
a cytosolic protein that binds to regions of the plasma membrane and helps initiate receptor-mediated endocytosis
241
clathrin-coated pit
aggregation of ligand-bound receptors on a cell membrane that pinches off and is internalized into the cell
242
endocytosis
process in which plasma membrane folds into the cell forming small pockets that pinch off to produce intracellular, membrane-bound vesicles
243
exocytosis
process in which intracellular vesicle fuses with plasma membrane, the vesicle opens, and its contents are liberated into the extracellular fluid
244
fluid endocytosis
invagination of a plasma membrane by which a cell can engulf extracellular fluid
245
phagocytosis
engulfment of particles by a cell
246
phagosomes
plasma-membrane-bound, intracellular sacs formed when a phagocyte engulfs a microbe
247
pinocytosis
endocytosis when the vesicle encloses extracellular fluid or specific molecules in the extracellular fluid that have bound to proteins on the extracellular surface of the plasma membrane
248
receptor-mediated endocytosis
the specific uptake of ligands in the extracellular fluid by regions of the plasma membrane the invaginate and form intracellular vesicles
249
receptors
for messengers: protein either on cell surface, in the cytosol, or in the nucleus that binds a chemical messenger such as a hormone or neurotransmitter and mediates its actions
in sensory system: specialized peripheral ending of afferent neuron, or separate cell intimately associated with it, that detects changes in some aspect of the environment
250
apical membrane
the surface of an epithelial cell that faces a lumen, such as that of the intestines; also known as luminal membrane
251
basolateral membrane
sides of epithelial cell other than luminal surface; also called serosal or blood side of cell
252
paracellular pathway
the space between adjacent cells of an epithelium through which some molecules diffuse as they cross the epithelium
253
transcellular pathway
crossing an epithelium by movement into an epithelial cell, diffusion through the cytosol of that cell, and exit across the opposite membrane
