BIO 112 exam 2 Flashcards
1
Q
Thermoregulation
A
The process by which animals maintain their body temperature within a normal range.
2
Q
What can happen to animals whose body temperatures are outside of a normal range.
A
Reduce the efficiency of enzymatic reactions, alter fluidity of cellular membranes, and affect other temperature-sensitive biochemical processes, potentially with fatal results.
3
Q
Endothermic (add examples)
A
Humans, mammals, and birds
They are warmed mostly by heat generated by metabolism
4
Q
Ectothermic
A
Non avian reptiles, fishes, amphibians, and most invertebrates
They gain most of their heat from external sources
5
Q
Integumentary system (what is it, why is it important)
A
The outer covering of the body, consisting of the skin, hair, and nails, very important in thermo regulation
6
Q
Insulation is important why?
A
A major thermoregulatory adaptation in mammals and birds is insulation, which reduces blood flow of heat between an animals body and its environment
7
Q
Two circulatory adaptations, what are they
A
Vasodilation- widens superficial blood vessels, increases flow
Vasoconstriction- reverse process, decreases flow
8
Q
Countercurrent exchange
A
The transfer of heat (or solutes) between fluids that are flowing in opposite directions
9
Q
How does the process of countercurrent exchange occur
A
Arteries and veins are located next to each other in countercurrent exchangers because blood flows through the arteries and veins in opposite directions, the arrangement allows heat exchange to be remarkably efficient. Warm blood moves from the body core in arteries, it transfers heat to the colder blood returning from the extremities in the veins. Most importantly heat is transferred along the entire length of the exchanger, maximizing the rate of heat exchange
10
Q
A way that animals cool down
A
Cooling by evaporative heat loss.
Panting, sweating, bathing can help animals to lose heat by carrying away heat in the water that come from their sweat glands
11
Q
Five major ways animals thermoregulate
A
- Insulation
- Circulatory adaptations
- Cooling by evaporative heat loss
- Behavioral responses
- Adjusting metabolic heat production
12
Q
Behavior responses in thermoregulation
A
When cold animals seek warm places, and expand a portion of their body exposes the heat source. When hot, they bathe, move to cool areas.
13
Q
Adjusting metabolic heat production
A
Muscle movement, shivering and thermogenesis and no shivering thermogenesis in as quickly as five or ten minutes
14
Q
Thermogenesis
A
Used to match changing rates of heat loss by such muscle activity as moving or shivering
15
Q
Non shivering thermogenesis
A
Some mammals, certain hormones can cause mitochondria to increase their metabolic activity and produce heat instead of ATP.
16
Q
Brown fat
A
Some mammals have brown fat in their neck and between their shoulders that is specialized for rapid heat production
17
Q
Acclimatization in thermoregulation
A
In birds and mammals, acclimatization to seasonal temperature changes often includes insulation, growing a thicker coat of fur in the winter and shedding it in the summer. Acclimatization often includes adjustments at the cellular level. Cells may produce variants of enzymes that have the same function but different optimal temperatures.
18
Q
Hypothalamus
A
The sensors for thermoregulation are concentrated in the hypothalamus, the brain region that also controls the circadian clock. Within the hypothalamus a group of nerve cells function as a thermostat, responding to body temperatures outside the normal range by activating mechanisms that promote heat loss or gain
19
Q
Fever
A
In the course of a viral or bacterial infection a fever may develop; an elevated body temperature. A variety of experiments have shown that fever reflects an increase in the normal range for the biological thermostat
20
Q
Bioenergetics
A
Determines the nutritional needs and is related to the animal’s size, activity, and environment.
21
Q
Metabolic rate
A
The sum of all the energy an animal uses in a given time interval
22
Q
Ways metabolic rate can be measured
A
Monitoring an animals heat loss
Amount of oxygen consumed or carbon dioxide produced
The rate of food consumption, the energy content of the food, and the chemical energy lost in waste product ( over long periods of time)
23
Q
Minimum metabolic rate
A
Animals must maintain a minimal metabolic rate for basic functions such as cell maintenance, breathing, and heartbeat.
24
Q
The basal metabolic rate (BMR)
A
The minimum metabolic rate of no growing endothermic that is at rest, has an empty stomach, and is not experiencing stress. BMR is measured under a comfortable temperature range- a range that requires no generation or shedding of heat above the minimum metabolic rate
25
standard metabolic rate (SMR)
The metabolic rate of a fasting, no stressed ectothermic at rest at a particular temperature is called its standard metabolic rate (SMR)
26
Influences on metabolic rate
Age, sex, size, activity, temperature, and nutrition
27
Torpor
A psychological state of decreased activity and metabolism, is an adaptation that enables animals to save energy while avoiding difficult and dangerous conditions
28
Hibernation
Along term torpor that is an adaptation to winter cold and food scarcity
29
Energy requirements, in ecosystems
Sunlight is captured by autotrophs converted to chemical energy via photosynthesis and converted by cellular respiration to release energy
30
Autotrophs
The producers
Capture energy via photosynthesis an endergonic reaction, requires energy. And Uses energy via cellular respiration an exergonic reaction
31
Heterotrophs
Consumers, Feed on organic materials for energy and materials , use energy via cellular respiration. Every time energy is converted from one form to another some heat is lost
32
Energy conservation
Adaptations enables animals to save energy and avoid difficult conditions
33
Estivation
Summer torpor saves energy when water is scarce or temperatures are too high
34
Regulator
Uses internal control mechanisms to moderate internal change in the face of external, environmental fluctuation
35
A conformer
Allows its internal condition to vary with certain external changes
36
Thermal neutral zone
An endothermic temperature tolerance range the basal rate of heat production is in equilibrium with the rate of heat loss to the external environment
37
LCT
Lower critical temperature
38
UCT
Upper critical temperature
39
The LCT and UCT vary with what
Species and season
40
Poikilotherm
Internal temperature varies along with that of the ambient environmental temperature (most ectotherms)
41
Homeotherm
Body temperature is relatively constant (endotherms)
42
The circulatory system connects organs of gas exchange with what?
Body cells
43
Open an closed circulatory systems have three basic components
1. A circulatory fluid (blood or hemolymph)
2. A set of tubes (blood vessels)
3. A muscular pump (heart)
44
Endotherms use ----- more energy than ectotherms
10x
45
Double fertilization
Separate and independently powered systemic and pulmonary circuits
46
Superior vena cava
Blood from head, neck, and forelimbs
47
Inferior vena cava
Blood from trunk and hind limbs
48
Tricuspid valve
Right atrioventricular valve
49
Bicuspid valve
Or mitral valve, left atrioventricular valve
50
Pulmonary valve
Semilunar valve that opens into the pulmonary trunk
51
Aortic valve
Opens into the aortic arch
52
"Lub"
Recoil of blood against closed AV valves
53
Dub
Recoil against semilunar valves
54
Cardiac cycle
Rhythmic cycle of the heart contracting and relaxing
55
Systole
Contraction= pumping phase
56
Diastole
Relation- filling phase
57
Cardiac output
The volume of blood pumped into the systemic circulation per minute
58
Heart rate
The pulse, the number of beats per minute
59
Stroke volume
The amount of blood pumped into a single contraction
60
The heart beat is generated by what?
Autorhythmic cardiac muscle cells
61
Sinoatrial (SA) node
Pacemaker
62
Atrioventricular (AV) node
Impulses delayed
63
Sympathetic nerves
Speed pacemaker
64
Parasympathetic nerves
Slow pacemaker
65
Blood pressure
The physical principles that govern movement of water in plumbing systems apply to the functioning of blood vessels
66
Central lumen
Vessel's cavity
67
Endothelium
Epithelial cells lining blood vessels
| Smooth to minimize resistance
68
Smooth muscle layer
Thicker around arteries than veins
69
Capillaries
- Only slightly wider than a red blood cell
- where exchange with interstitial fluid occurs
- flow controlled by precapillary sphincters
70
Basal lamina
Extra cellular layer of thin Waller capillaries, facilitate materials exchange
71
Why is blood velocity the slowest in capillary beds
High resistance and large total cross sectional area
72
Arteries
(Away) thicker walled to accommodate higher pressure
73
Veins
(Towards)
- blood flows mainly a result of muscle action
- valves maintain unidirectional blood flow
74
Vessel function
Blood flows from areas of higher pressure to areas of lower pressure
75
Recoil of elastic arterial walls
Maintains blood pressure at diastole
76
Resistance
Blood flow in the narrow diameters of tiny capillaries and arterioles dissipates much of the pressure
77
Systolic pressure
Pressure in arteries during ventricular systole
78
Diastolic pressure
The pressure in the arteries during diastole ( atrial wall recoil)
79
Vasoconstriction
The contraction of smooth muscle in arterioles walls
- increases blood pressure
- endothelin (a peptide) induced
80
Vasodilation
The relaxation of smooth muscles in the arterioles; causes blood pressure to fall, nitric oxide( NO) induced
81
Function of blood
Exchange, transport, and defense
82
Plasma
45% blood volume
Specialized connective tissue
90% water
83
Electrolytes
Inorganic salts in the form of dissolved ions
84
Plasma proteins
Influence blood pH, osmotic pressure, and viscosity
| - various plasma proteins function in lipid transport, immunity, and blood clotting
85
Two types of cells suspended in blood plasma with platelets
Erythrocytes- red blood cells
| Leukocytes- white blood cells
86
Five facts about Erythrocytes
Red blood cells
1. Transport oxygen
2. most numerous blood cell
3. Contain hemoglobin (iron containing protein that transports oxygen
4. No nucleus when mature
5. Live 120 days
87
3 facts about leukocytes
White blood cells
- five major types: monocytes, neutrophils, basophils, eosinophils, and lymphocytes
- function in defense by phagocytizing bacteria and debris or by producing antibodies
- found both inside and outside of the circulatory system
88
Platelets
Fragments of cells, function in blood clotting
89
Stem cells location and three facts
In the red marrow of bones
- produces erythrocytes, leukocytes, and platelets
- erythropoietin (EPO) - hormone stimulates erythrocytes production when oxygen delivery is low
- blood doping
90
Coagulation
The formation of a solid clot from liquid blood
91
Blood clotting
A cascade of complex reactions converts inactive fibrinogen to fibrin forming a clot (converted by enzyme thrombin)
92
Thrombus
A blood clot formed within a blood vessel, can block blood flow
93
Cardiovascular disease
Disorders of the heart and the blood vessels
94
Atherosclerosis
Caused by the buildup of fatty deposits (plaque) within arteries
95
Low density lipoprotein (LDL)
Delivers cholesterol to cells for membrane production
96
High density lipoprotein (HDL)
Scavengers excess cholesterol for return to the liver
97
Heart attack
Myocardial infarction the damage or death of cardiac muscle tissue from blockage of coronary arteries
98
Stroke
Death of nervous tissue in the brain, usually from rupture or blockage off arteries in the head
99
Neurons
Nerve cells that transfer information within the body
100
Two types of signals used by neurons to communicate
```
Electrical signals (long-distance)
Chemical signals (short-distance)
```
101
Dendrite
Receives and carries information toward cell body
102
Cell body
Location of most neurons organelles (including nucleus)
103
Axon
Transmits information to other cells, carries impulse away from cell body
104
Heart attack
Myocardial infarction the damage or death of cardiac muscle tissue from blockage of coronary arteries
105
Stroke
Death of nervous tissue in the brain, usually from rupture or blockage off arteries in the head
106
Neurons
Nerve cells that transfer information within the body
107
Two types of signals used by neurons to communicate
```
Electrical signals (long-distance)
Chemical signals (short-distance)
```
108
Dendrite
Receives and carries information toward cell body
109
Cell body
Location of most neurons organelles (including nucleus)
110
Axon
Transmits information to other cells, carries impulse away from cell body
111
Axon hillock
Come shaped base of axon typically where signals that travel down axon are generated
112
Synapse
Junction between axon, transmitting information to another receiving cell
113
Synaptic terminal
Specialized synaptic junction at each axon branch
114
Neurotransmitters
Chemical messengers that transmit information from transmitting cells (presynaptic cell) to receiving cells (post synaptic cell)
115
Glial cells
Supporting cells in vertebrates and most invertebrates
- nourish, neurons, insulate axons and regulate extra cellular fluid surrounding neurons.
- outnumber neurons in mammalian brain 10-50 fold
116
Oligodendrocytes are in what part of the nervous system
The CNS
117
Schwann cells are in the
PNS
118
Four types of neurons
Sensory neurons
Interneurons
Motor neurons
Neuroendocrine
119
Sensory neurons
Receives stimuli from environment
120
Interneurons
Act between neurons
121
Motor neurons
Transmit information to muscles from inter neurons
122
Neuroendocrine cells
Neurosecretory cells- produce hormones
123
CNS
Central nervous system- brain and nerve cord, ganglia
- ventral nerve chord
- dorsal nerve chord
124
PNS
Peripheral nervous system- everything outside CNS
125
Somatic nervous system
SNS- voluntary, skeletal
126
Autonomic nervous system
ANS - involuntary, smooth muscle, cardiac muscle glands, sympathetic and parasympathetic divisions
127
Enteric Nervous System
ENS- involuntary, smooth muscle, glands, neurosecretory cells
128
Membrane potential
A neuron function of the transfer of information
| - voltage difference across a membrane
129
Resting potential
The membrane potential of a neuron not sending signals
130
Sodium potassium pumps
Use ATP energy to maintain K- and Na+ gradients across the plasma membrane
131
Na+ concentration is highest where?
outside of the cell
132
K+ concentration is highest where?
inside of the cell
133
cl- concentration is highest where?
outside of the cell
134
negatively charged proteins inside cells that contribute to what?
internal negatieve charge
135
equilibrium potential
(Eion) the membrane voltage for a particular ion at equilibrium (movement out=movement in)
136
Eion=?
62 mV (log[ion]outside/[ion]inside)
137
graded potential
a shift in membrane potential that varies with stimulus strength decay with time and distance
138
action potential
massive change in membrane voltage. have a constant magnitude and can regenerate in adjacent regions of membrane. spread along axons and thus transmit signals over distances.
139
gated ion channels
open and close in response to stimuli. changes membrane permeability to particular ions, altering membrane potential.
140
voltage gated ion channels
open or close in response to membrane potential of certain level passing. positive feedback in Na+ channels and depolarization.
141
Hyperpolarization
increase in the magnitude of the membrane potential. In resting neuron, hyperpolarization increases outflow of positive ions or inflow of negative ions.
142
depolarization
reduction in the magnitude of the membrane potential. involves faded sodium channels in resting neuron
143
myelin sheath
insulates vertebrate axons, it increases action potential speed, its made by glial cells
144
saltatory conduction
action potentials in myelinated axons jump between the nodes of ranvier
145
nodes of ranvier
gaps in the myelin sheath where voltage-gated Na+ channels are found and action potentials formed)
146
Synapse
junction between neurons and another cell, neurons communicate with other cells across synapses
147
electrical synapses
electrical current flows from one neuron to another through gap junctions
148
gap junctions
connexion transmembrane proteins form tiny fluid filled tubes small ions can pass through)
149
chemical synapses
chemical neurotransmitter carries information between neurons. slower, more common.
150
neurotransmitter
chemical messenger secreted by neurons
1. synthesized in the presynaptic neuron
2. packed in synaptic vesicles at the synaptic terminal
3. action potential opens Ca+ channels, causes release
4. diffusion across the synaptic cleft
5. ligand-gated ion channels on postsynaptic cell
6. post-synaptic cell action potential initiated
151
ionotropic receptor
post synaptic receptors, ligand gated ion channel- receptor is both neurotransmitter binding site and ion channel
152
metabotrophic receptor
second messenger systems- neurotransmitter binding site connected to ion channel by a series of molecules including a G protein. onset slower, last longer, amplifying
153
excitatory postsynaptic potentials (EPSPs)
depolarization that brings the membrane potential toward threshold. ion channel is permeable for Na+ and K+ or Ca+
154
inhibitory postsynaptic potentials (IPSPs)
hyperpolarizations that move the membrane potential farther from threshold. Ion channel is permeable for only Cl- (move in) or K+ (move out)
155
temporal summation
two EPSPs or IPSPs produced in rapid succession at same synaptic terminal are summed
156
spatial summation
EPSPs and IPSPs produced nearly simultaneously by different synapses on the same postsynaptic neuron ass together
157
neurotransmitters terminated
1. inactivating enzymes
2. transport channel presynaptic cell uptake (ex;serotonin)
3. diffusion out of cleft
158
acetylcholine
major neurotransmitter,
invertebrates: muscle stimulation at neuromuscular junction.
vertebrates: memory function, learning, neuromuscular stimulant
159
ionotropic
(ligand gated)- excitatory at neuromuscular junction
160
metabotropic
inhibitory at heart muscle, slows HR
161
Glutamate
amino acid (rods and cones in eye retina) alcohol binds to glutamate receptors
162
Gamma-Aminobutyric acid (GABA)
neuromuscular inhibition-opens Cl- or K+ channels to hyper polarize cells=IPSP. valium binds to GABA receptors, alcohol enhances inhibitions
163
Biogenic Amines
active in the CNS and PNS
164
epinephrine
(sympathetic nervous system at post ganglion synapsis; attentiveness, emotions, sleeping, dreaming, and learning
165
dopamine
sleep mood, attention and learning ("cognitive alertness"parkinson's disease and schizophrenia involve altered levels of dopamine)
166
serationin
sleep mood, attention and learning (altering levels treats depression, anxiety, social phobia)
167
neuropeptides
(relatively short chains of amino acids)
| - substance P and Endorphins- (Increase pain perception, endorphins reduce pain perception)
168
Opiates
(like heroin) bind to endorphin G-protein-coupled receptors, can be used as painkillers
169
nitric oxide (NO) and carbon monoxide(CO)
local regulators in the PNS
170
gases are
1. not stored in cytoplasmic vesicles, but synthesized on demand
2. broken down within a few seconds of production
3. viagra inhibits enzyme that breaks down NO, keeping smooth muscle of blood vessels of spongy erectile tissues relaxed and full of blood.
171
nerves
the bundled axons of multiple neurons (=nerve cells)channel and organize information flow through the nervous system
172
nervous system
circuits of neurons and supporting cells
173
nerve nets
simplest of nervous systems
174
ganglia
clusters of nerve cell bodies in the PNS
175
nucleus
a cluster of nerve cell bodies in the CNS
176
cephalization
an evolutionary trend toward clustering sensory neurons and interneurons at the anterior end of the body
177
glial cells= glia= neuroglia
cells that nourish, support, and regulate the function of neurons , nervous system development
178
four main functions
1. surround neurons and hold them in place.
2. supply nutrients and oxygen to neurons
3. insulate one neuron from another
4. destroy pathogens and remove dead neurons
179
six main types of glial cells
1. ependymal
2. astrocytes
3. radial glia
4. oligodendrocytes
5. schwann cells
6. microglia
180
ependymal cells
line the ventricles of the brain and spinal cord, lumen, produce and circulate cerebrospinal fluid.
181
astrocytes
participate in forming the blood brain barrier. can be stem cells (wrap around a neuron and capillary to hold things in place)
182
radial glia
form paths for neurons growing from neural tube to follow. can be stem cells.
183
oligodendrocytes
form myelin sheaths in CNS
184
schwann cells
form myelin sheaths in PNS
185
microglia
immune cells in the CNS, derived from bone marrow and blood stem cells
186
ventricles
cerebrospinal fluid filled cavities in brain
187
gray matter
neuron cell bodies, dendrites, and unmyelinated axons, outer brain
188
white matter
bundles of myelinated axons (inner brain)
189
spinal cord
conveys information to and from the brain and generates basic patterns of locomotion
190
reflex
automatic response to a stimulus
191
gray matter
unmyelinated (inner spine)
192
white matter
myelinated (outer spine)
193
peripheral nervous system
everything outside the nervous system
194
afferent neurons
carry signals from sensory receptors to CNS
195
motor system
carries signals to skeletal muscles (voluntary and involuntary, also reflexes like knee-jerk
196
autonomic nervous system
regulates smooth and cardiac muscles (generally involuntary, sympathetic and parasympathetic divisions
197
what happens when the body goes through sympathetic - "flight or fight"
heart beats faster, reduce digestion, increase production of epinephrine or adrenal medulla, liver converts glycogen to glucose, synapses just outside spinal cord,
198
acetylcholine
pre ganglion
199
norepinephrine
post ganglion
200
what happens during parasympathetic "rest-digest"
heart rate decreases, pupil of eye constricted, digestion enhanced- salivary gland secretions, stomach, intestine, gallbladder and pancreas activity stimulated,
glycogen production increases
201
acetylcholine
both pre and post ganglion
202
ocelli
light detecting organs "eyespots" pair located near the head.
203
taxis
movement in response to some stimulus (planar exhibit negative phototaxis in avoiding light.)
204
compound eye
insects and crustaceans,
205
ommatidia
light detectors, up to several thousand per eye, effective at detecting movement, insects have excellent color vision, and some can see ultraviolet
206
single lense eyes
vertebrates and others
207
rods
photoreceptors
208
cones
photoreceptors and color receptors
209
horizontal cells
carry signals from one rod or cone to other photoreceptors and several bipolar cells
210
bipolar cells
may be inhibited by distant horizontal cells
211
amacrine cells
distribute information rom one bipolar cell to several ganglion cells
212
ganglion cells
receives information from an array of rods and cones from a receptive field ( part of visual field a ganglion cell responds)
213
lateral inhibition
horizontal cell inhibit more distant photoreceptors and bipolar cells that are not illuminated. sharpens edges and enhances contrasts of image.
214
paracrine signaling
signals released by one cell diffuses locally to act on nearby cells to respond
215
synaptic signaling
at neuron synapses action potential stimulates neurotransmitter release
216
endocrine signaling
hormal signaling, cells release hormone molecules which diffuse into and travel via circulatory system to distant target cells
217
hormone
chemical messengers that act on specific target cells in other parts of the body changing target cell function
218
plant growth regulators
hormones, travel in vessels, though cells or diffusion through air as gas
219
gas
(some plant hormones are gas) eg. ethylene promotes fruit ripening
220
3 stages of cell signaling
1. reception
2. transduction
3. response
221
reception
signal molecule binds to receptor protein on a cell surface (surface recognition proteins)
222
transduction
receptor protein changes, usually signal transduction pathway involves a series of different molecules
223
response
some cellular activity resulting from transducer signal
224
ligand
a molecule that binds specifically to another (often larger) molecule
225
kinase
enzyme that adds phosphate group
226
monomers
inactive form- ligand binding site extra cellular, double helix plasma membrane, cytoplasmic tyrosine kinase
227
cytoplasmic tyrosine kinase
(transfer phosphate group from ATP to tyrosine)
228
dimers active form
1. each kinase phosphorylates tyrosine on the other monomer tail.
2. relay proteins bind to specific phosphorylated tyrosine- structural change- activated protein triggers transduction pathway
229
a single ligand binding even can trigger what?
can trigger many pathways in RTKs
230
ligand gated ion channels+ ionotrophic receptors
binding to transmembrane protein opens or closes ion channel result is changes in ion concentration inside the cell
231
transcript factor
controls which genes are turned on and transcribed into mRNA
232
in eukaryocytes a collection of proteins called transcription factor mediate what?
the binding of RNA polymerase and DNA to transcribe gene into mRNA
233
transduction
cascades of molecular interactions relay signals from receptors to target molecules inside cell
234
signal transduction pathway
a series of steps in which a signal is changed into a different form ("relay molecules" the molecules in the pathway)
235
three functions of the signal transduction pathway
1. adding or removing phosphate groups to active/inactive proteins
2. release other small molecule messengers
3. release small ion messengers
236
protein kinases
enzymes that add phosphate groups to proteins (phosphorylation)
237
protein phosphates
enzymes that rapidly remove phosphate groups from proteins (dephosphorylation)
tyrosine kinase
serine/ threonine kinases important in animals, plants, fungi
238
Cyclic AMP (cAMP)
is one of the most widely used second messengers
239
adenylyl cyclase
enzyme in the plasm membrane that converts ATP to cAMP in response to an extracellular signal
240
Ca2+
cytoplasmic concentrations of calcium usually low. Small numbers of ions can be large change. calcium usually released from ER in transduction pathway
241
IP3
inositol triphosphate- diacylglycerol (DAG) secondary messengers that are produced by cleavage of phospholipid in plasma membrane
242
scaffolding proteins
increase effieciecy of response
243
synthesis
enzymes or proteins can be altered by turning genes on and off
244
transcription factor
a regulatory protein that binds to DNA and affects transcription of specific genes
245
activity
instead of turning completely off or on, activity can be altered
246
amplification
every enzyme in a cascade can catalyze a number of reactions, amplifying products
247
intercellular communication is classified b two criteria
the type of secreting cell (endocrine, neuron) the route taken by the signal in reaching its target (local diffusion, circulatory system)
248
local regulators
molecules that act over short distances, reaching target cells solely by diffusion
249
paracrine signaling
the target cells lie near the secreting cells
250
autocrine signaling
the target cell is also the secreting cell
251
synaptic signaling
neurotransmitters secreted a signals at a synapse (specialized junctions neurons form with target cells)
252
long distance regulators
molecules act on target cells at a distance from source cell.
253
neuroendocrine signaling
neurosecretoy cells specialized neurons secrete neurohomormones (travel to target cells by way of the circulatory system)
254
apoptosis
a type of programmed cell death that integrates input from multiple signaling pathways.
255
quorum sensing
sensing the concentration of such signaling molecules allows bacteria to monitor the local entity of cells
256
biofilm
an aggregation of bacteria cells adhered to a surface and they derive nutrition from the surface they are on
