Exam 1 Flashcards
1
Q
Homeostatically regulated core body temperature
A
37C (98F)
2
Q
Homeostatically regulated mean arterial blood pressure
A
80-100 mmHg
3
Q
Homeostatically regulated [Ca++] extracellular
A
1-3 mM
4
Q
Homeostatically regulated [K+] extracellular
A
3-5 mM
5
Q
Homeostatically regulated [H+] or pH extracellular
A
7.35-7.45
6
Q
Homeostatically regulated [Glucose] in the blood plasma
A
100 mg/dL (milligrams per deciliter)
7
Q
Homeostatically regulated Blood osmolarity
A
300 milliosmoles/Liter
8
Q
Homeostatically regulated Arterial blood oxygen levels PO2
A
70-100 mmHg
9
Q
Homeostatically regulated Arterial carbon dioxide levels PCO2
A
34-45 mmHg
10
Q
Regulated variable
A
Any variable for which sensors are present in the system and the value of which is kept within limits by a negative feedback system in the face of perturbations in the system.
11
Q
Sensor (receptor)
A
A “device” that measures the magnitude of some variable by
generating an output signal (neural or hormonal) that is proportional to the magnitude of the stimulus. Detects changes in the environment
12
Q
Integrating center (controller, command center)
A
Determines and initiates the appropriate physiological response to any change or disturbance of the internal environment
13
Q
Effectors
A
Make changes according to the information they receive from the integrating center. They determine the value of the regulated (sensed) variable.
14
Q
Negative feedback system
A
A change in a variable leads to responses that move the variable in the direction opposite of the initial change
15
Q
Nervous system reflex
A
A specific involuntary, unlearned “built-in” response to a particular stimulus
16
Q
Parts of a feedback loop
A
Receptor (sensor) – afferent pathway - integrating center – efferent pathway – effectors
17
Q
Set point
A
the “steady-state” condition where the variable is held relatively constant; REQUIRES ENERGY; has variability
18
Q
Dynamic constancy
A
levels of a variable can change over short periods of time but remain relatively constant over long periods of time
19
Q
Afferent pathway
A
signal’s pathway TO control center
20
Q
Efferent pathway
A
signal’s pathway AWAY FROM control center
21
Q
Body temperature feedback example: Stimulus
A
change (increase or decrease) in body temperature
22
Q
Body temperature feedback example: Receptors
A
temperature-sensitive neurons (increase their signaling rate)
23
Q
Body temperature feedback example: Integrating/control center
A
specific neurons in brain (compare to set points; alter rates of firing)
24
Q
Body temperature feedback example: Effectors
A
cold: smooth muscle in skin blood vessels & skeletal muscle (decrease blood flow & shivering)
hot: sweat glands
25
Endocrine system reflex
negative feedback loop involving hormones (ex: blood glucose regulation)
26
True/False: all physiological variables are homeostatically regulated
False
27
Positive feedback
a change in variable leads to responses that move the variable in the same direction as the initial change
28
Examples of useful positive feedback
blood clotting, neuron-opening of voltage-gated Na+ channels to cause an action potential, contractions of the uterus during childbirth
29
Most disease is due to a disturbance in ______.
Homeostasis
30
Cell membrane
structure phospholipid bilayer with embedded proteins
31
Phospholipids
consist of a hydrophilic head molecule and a hydrophobic tail
32
Which substances are prevented from directly moving through the plasma membrane by the phospholipid bilayer?
Hydrophilic
33
Selective permeability
size, charge, polarity dictate permeability
34
What molecules can PASSIVELY diffuse through the cell membrane?
some small uncharged molecules such as gases like O2 or CO2, fatty acids, steroid hormones
35
What molecules move through PROTEINS embedded in the membrane?
Hydrophilic or polar molecules such as H2O, amino acids, glucose, and ions like Na+, Ca++, Cl-, or K+
36
Cytoplasm
cellular region between the nucleus and plasma membrane (includes the cytosol and organelles)
37
Cytosol
fluid in which the organelles are suspended, composed of water and many dissolved substances, contains protein fibers that make up the cytoskeleton
38
Nucleus
large spheroid body that contains the cell's genetic material
39
Organelles
sub-cellular structures within the cytoplasm (ex: mitochondria, endoplasmic reticulum, Golgi apparatus, lysosome, peroxisome, etc.)
40
Nucleus function
control center of the cell that is responsible for transmitting genetic information and providing instructions for protein synthesis
41
Nucleus structure
surrounded by the nuclear envelope; nuclear pores join the 2 membranes of the nuclear envelope together
42
Nuclear envelope
double phospholipid bilayer with lumen in between
43
Nucleoli
dense structures which contain genes for forming the RNA associated with ribosomes
44
Chromatin
threadlike material composed of DNA and histone proteins
45
DNA polymerase
enzyme that complements strand with A, T, C, or G to copy the genome in DNA replication
46
Helicase
enzyme that unwinds DNA
47
Semi-conservative
DNA replication is ___ because it uses one old strand and adds on a new
48
Genes encode ________,
Proteins
49
Ribosomes
small granules composed of protein and RNA; site of protein synthesis
50
Proteins
molecules composed of long chains of amino acids bonded by peptide bonds; workhorse of the body
51
Split gene
genes have introns and exons so splicing occurs; RNA polymerase only transcribes part of the genome
52
RNA polymerase
enzyme that complements strand with A, U, C, or G to copy the genome in transcription
53
Where does replication occur?
Nucleus
54
Where does transcription occur?
Nucleus
55
Where does translation occur?
In cytosol on ribosomes
56
Codons
three bases that encode an amino acid
57
Protein examples
enzymes, binding proteins, regulatory proteins, signaling proteins, immunoglobins, receptor, membrane transporters, membrane channels, cytoskeletal proteins
58
Cytoskeleton
microfilaments and microtubules; gives the cell its structure and is important for forming cell compartments and transport
59
Rough endoplasmic reticulum
extensive, enclosed network of membranes with ribosomes on the surface; makes luminal, extracellular, or membrane proteins (translate proteins into the phospholipid bilayer)
60
Smooth endoplasmic reticulum
membrane system composed of tubules with no ribosomes attached, site of lipid and steroid synthesis; also, stores calcium in some cell types; makes membranes
61
Golgi apparatus
stack of smooth membrane sacks with associated vesicles; modifies proteins received from the rough ER and packages protein into vesicles
62
Phagocytosis
a type of endocytosis; energy-requiring; envelops large particles; ex: WBC enveloping bacteria
63
Pinocytosis
a type of endocytosis; energy-requiring; smaller vesicles form spontaneously to bring in small molecules; occurs in more cell types
64
Receptor-mediated endocytosis
a type of endocytosis; energy-requiring; much more regulated; ligands bind to transmembrane receptors and vesicles are activated to internalize the ligand
65
Lysosome
membrane bound sac that contains digestive enzymes
66
Peroxisome
membrane bound sac which contains enzymes which break down toxic substances that would otherwise harm the cell if broken down normally
67
Mitochondria structure
double membrane, have DNA that encodes proteins, can replicate
68
Mitochondria function
generates ATP, CO2, H2O, and heat
69
ATP
a high energy molecule; energy released from cleavage of the energy phosphate bond fuels cellular activities, from muscle contraction to the transport of substances in and out of cells to enzyme reactions; critical for homeostasis!
70
Plasma membrane
site of cellular boundary and transcellular movement of solutes and solvents
71
Main difference between interstitial fluid and plasma
plasma is inside blood vessels and has a high concentration of protein
72
The magnitude of flow between ECF and ICF is a direct function of __________.
The magnitude of the energy gradient that is present
73
Types of passive transport
simple diffusion; facilitated diffusion; ion channels; water channels and osmosis
74
Simple diffusion
flow of a substance across a membrane from a higher to a lower concentration
75
What does rate/flow of diffusion depend upon?
concentration difference, temperature, permeability of the membrane, and surface area
76
What molecules can pass through by simple diffusion?
small and uncharged or hydrophobic molecules such as O2, CO2, fatty acids, steroid hormones
77
Facilitated diffusion
transporter proteins transport molecules too large or polar to directly diffuse across the membrane (ex: glucose); still down concentration gradient
78
Facilitated diffusion selectivity & saturation
transporters are specific for their ligand and there is a maximum flux of molecules that can be reached due to limited number of carriers
79
Facilitated diffusion mechanism
series of conformational changes; when something binds to the transporter it undergoes a shape change and thus function change to allow a molecule to flow through
80
Ion channels
integral membrane proteins that form aqueous pores allowing ions to permeate the membrane
81
What specifies ion selectivity?
diameter of the pore
82
What does net diffusion of ions depend on?
ion concentration and membrane potential
83
Gating
the process of transitioning between closed and open conformations
84
K+ concentration
extracellular: 5mM (low); intracellular: 150mM (high)
85
Na+ concentration
extracellular: 145mM (high); intracellular: 15mM (low)
86
Cl- concentration
extracellular: 108mM (high); intracellular: 10mM (low)
87
Ca++ concentration
extracellular: 1mM (higher); intracellular: 10^-9 (very low)
88
Osmosis
the net diffusion of water across a membrane
89
Aquaporins
channel proteins that facilitate osmosis; expression and insertion into the membrane varies among cell types
90
Osmolarity
total concentration of solute; also refers to water concentration because the higher the Osm, the lower the water concentration
91
Tonicity
reflects a solution's effect on a cell's volume
92
Normal osmolarity inside a cell
300 mOsm
93
Isotonic
solution with the same osmolarity as the inside of a cell; no change in cell volume
94
Hypotonic
solution with a lower osmolarity than the inside of a cell; cell swells
95
Hypertonic
solution with a higher osmolarity than the inside of a cell; cel shrinks
96
Primary active transport
hydrolysis of ATP required for function of carriers; molecule or ion binds to "recognition site" on one side of carrier protein; carrier protein undergoes conformational change to opposite side of membrane
97
Na+/K+ ATPase
active transport; extrudes 3 Na+ and transports 2 K+ inward against concentration gradient; helps maintain ionic gradients
98
Secondary active transport
coupled transport (co-transport); energy needed for "uphill" movement obtained from "downhill" transport of Na+; does work that was established by primary active transport; ex: glucose UP its concentration gradient
99
Totipotent stem cells
fertilized egg cell; can develop into a person in utero
100
Pluripotent stem cells
can develop into any cell type
101
Multipotent stem cells
can develop into a limited number of cell type within a lineage
102
Epithelial cells and tissue
consist of cells that form membranes which cover and line body surfaces and form glands; regulate movement of molecules into or our of body; secretion
103
Exocrine glands
secrete chemicals into ducts that lead to outside the membrane
104
Endocrine glands
secrete chemicals (hormones) into the blood
105
Connective cells and tissues
characterized by large amount of extracellular material (matrix) between cells; connective tissues, fat, cartilage, bone, and blood cells
106
Muscle cells and tissues
conduct electrical signals for contraction (generation of force0
107
Skeletal muscle
voluntary; generally attached to bones; arranged in parallel bundles; each cell controlled individually (graded contraction)
108
Smooth muscle
involuntary; found in digestive tract, blood vessels, bronchioles (lungs), ducts of urinary and reproductive system; show circular and longitudinal arrangements (constrict and push)
109
Cardiac muscle
involuntary; found only in the heart; short branched and highly interconnected to coordinate pumping
110
Neurons and nervous tissue
conduct electrical signals to communicate information
111
Cell signaling
how cells communicate with each other; 4 types
112
Autocrine signaling
autocrine substance acts on the same cell that secreted the substance
113
Paracrine signaling
target cells in close proximity to site of release of paracrine substance
114
Neuronal signaling
fast, specific; neuron or effector cell in close proximity to site of neurotransmitter release
115
Endocrine signaling
distant, diffuse; target cells in one or more distant places in the body
116
Receptors
gate-keepers of cell responsiveness to ligands
117
Intracellular receptors
hydrophobic ligands diffuse across the plasma membrane into the cell & bind to induce conformational changes leading to alter gene transcriptional activity; slower but sustained respinses
118
Membrane (integral) receptors
hydrophilic ligands bind on the outside of the cell leading to conformational changes and cellular responses involving changes in many cellular proteins; faster and less sustained responses
119
Resting membrane potential (RMP)
the membrane potential of the inside of a cell (-90 to -65 mV) compared to the outside of a cell (0 mV)
120
Depolarization
the membrane potential becomes less negative inside of a cell becomes more positive with respect to the RMP
121
Repolarization
a return to the RMP
122
Hyperpolarization
the membrane potential becomes more negative inside of a cell with respect to RMP
123
Action potential
an all or none rapid depolarization and subsequent repolarization in membrane potential with a characteristic pattern caused by the opening and closing of voltage-gated ion channels (in neurons and muscle cells)
124
Passive ion channels
ion channels that are always open and allow ions to move down their concentration and electrical gradients (usually selective for K+); sometimes called "leak channels"
125
Voltage-gated channels
open or close when they detect a change in the membrane potential; open and then inactivate when the membrane depolarizes; close when the membrane repolarizes
126
Why is RMP negative?
K+ flow out of the cell is much greater than Na+ into the cell due to K+ leak channels
127
Basic functions of the nervous system (3)
sensory detection, information processing, behavior
128
Sensory detection
transducing environmental signals into neural signals (sound, smell, heat, etc.)
129
Information processing
transmission, integration, storage (memory), retrieval, perception, thought, learning, planning/implementation, emotion
130
Behavior
cognition, movement, autonomic response, language
131
Central nervous system
brain and spinal cord
132
Peripheral nervous system
cranial and spinal nerves
133
Spinal cord functions
conduit for incoming sensory data and outgoing movement commands; provides for spinal reflexes, which are simple automatic actions not involving the brain
134
Brain function
control center for the entire nervous system
135
Brain stem
links the spinal cord to the brain; regulation of basic physiological functions (ex: breathing rate, heart rate); composed of midbrain, pons, and medulla oblongata
136
Thalamus
relay station for sensory information; consciousness and sleep; center of brain connected to brain stem
137
Cerebellum
coordination of our movement, sense of balance, and motor and procedural learning; at base of brain
138
Limbic system
plays a role in our survival, memory, and emotions; important subregions
139
Hypothalamus
a metabolic sensor (blood to brain), coordinates the autonomic nervous system, and plays a major role in regulating basic drives such as hunger, thirst, and sex; center of brain
140
Hippocampus
involved in the creation of memories
141
Amygdala
plays a major role in regulating our emotional experiences, especially fear, anger, and aggression; PTSD affects this
142
Cerebral cortex
information processing center, learning and memory ("higher-level" cognitive processing)
143
"Higher level" cognitive processing
perception, language, memory, decision making, memory, attention, perceptual awareness, thought, language, and consciousness
144
PNS function
gathers info about the external environment and the body's internal environment for the brain through sensory neurons; serves as the conduit for the brain's commands to the rest of the body through motor neurons
145
Somatic nervous system
carries sensory input from receptors to the CNS and relays commands from the CNS to the skeletal muscles to control their movement
146
Autonomic nervous system
regulates our internal environment; consists of two parts
147
Sympathetic nervous system
in control when we are very aroused and prepares us for defensive action; fight or flight
148
Parasympathetic nervous system
in control when the aroused state ends to return our body to its normal resting state
149
Endocrine glandular system
works with the ANS in responding to stress, and plays a role in basic behaviors and bodily functions; secrete hormones
150
Why is gray matter darker?
cell bodies and blood vessels
151
Why is white matter lighter?
heavily myelinated axons
152
Neurons
responsible for information transmission throughout the nervous system
153
Glial cells
do not directly transmit information, but instead support neurons in their work by disposing of waste products of neurons, keeping their chemical environment stable, and insulating them
154
Dendrites
the fibers that project out of the cell body, receiving information from other neurons; undergo graded potentials
155
Cell body
contains the nucleus of the cell and other biological machinery to keep the cell alive
156
Axon
transmits messages through the neuron; undergo action potentials
157
Axon terminals
at the end of the axon and send messages to a different neuron
158
Two features for long distance communication
morphological and functional asymmetry; unidirectional signaling
159
Interneurons
exist only in the CNS; broad class; connect with each other, sensory, and motor neurons; create circuits
160
Sensory neurons
carry information to the CNS from the sensory receptor in the eyes, muscles, and glands (afferent)
161
Motor neurons
carry movement commands from the CNS to the rest of the body (efferent)
162
Oligodendrocytes
myelinate axons in the CNS; provides insulation for axonal conductance
163
Schwann cells
myelinate axons in the PNS; provides insulation for axonal conductance
164
Ependymal cells
produce CSF; cushions and nourishes the brain
165
CSF
protects brain, fluid buffer; buoyancy; receives and clears waste
166
Astrocytes
maintain the BBB with their "end feet"; contain chemical communication/synaptic transmission (axon/dendrites wrap themselves around synapses so chemicals don't leak out); extracellular sponges--soak up and buffer excess chemicals; metabolic support
167
Microglia
immune sentinels--resident phagocytes, cleanup crew--removes microbes and foreign pathogens, neuron maintenance--synaptic pruning
168
Graded potential
Magnitude changes with magnitude of triggering event; duration varies with duration of triggering event; decremental conduction; passive spread; can be summed; depolarization or hyperpolarization
169
Action potential characteristics
once the stimulus threshold is reach, magnitude doesn't change; propagates without degradation; magnitude of triggering response coded in frequency; very large, very rapid alteration
170
Axon hillock
where axon emerges from cell body; where AP originates; high density of voltage-gated Na+ channels
171
Threshold potential
voltage-gated Na+ channels open; send ions to get to -55mV
172
Rising phase
Na+ rushes in, positive feedback loop up to +30mV; voltage-gated K+ channels begin to open
173
Peak/Overshoot
membrane potential goes close to Na+ equilibrium potential; voltage-gated K+ channels open
174
Falling phase
Voltage-gated Na+ channels inactivate; voltage-gated K+ channels remain open
175
Undershoot/Hyperpolarization
voltage-gated Na+ channels are closed, deactivated; cell goes towards K+ equilibrium potential
176
RMP restored
voltage-gated K+ channels are closed
177
Signal propagation depends on...
membrane resistance, intracellular (axial) resistance, membrane capacitance
178
Resistance
degree a substance opposes passage of electric current
179
Capacitance
ability of something to hold charge
180
Myelin sheath
layers of lipid wrapped around axons that allow electrical messages to be transmitted faster within the neuron
181
Saltatory conduction
jumps in conduction
182
Nodes of Ranvier
short unmyelinated sections along the axon where the action potential is regenerated by a chain of positively charged ions pushed along by the previous segment
183
Graded response production
more intense and longer duration stimuli produce more frequent APs -> more frequent APs release more neurotransmitter -> more neurotransmitter increases the likelihood the next neuron will have an AP
184
Synapse
site of information transfer
185
Presynaptic element
axon terminal; contains synaptic vesicles filled with chemical transmitters
186
Postsynaptic element
dendrite; high density of receptors
187
3 types of synapses
axodendritic, axosomatic, axoaxonic
188
Electrical synapse
gap junctions allow direct ionic current flow between cells; very fast; found in the brain, but much less numerous than chemical synapses
189
Chemical synapse
uses neurotransmitters released from presynaptic neuron that bind to receptor proteins on postsynaptic cell to alter its membrane potential; synaptic cleft, convert APs to chemical signals then back to APs; produces a graded potential
190
CNS synapse
between CNS neurons; can create convergence (many synapses on one neuron integrate to determine output signal) or divergence (one neuron synapses onto many neurons)
191
Neuromuscular junction
synapse between motor neuron axon and skeletal muscle fiber; one to one AP transmission
192
5 steps of synaptic transmission
synthesis, storage, release, receptor binding, removal/inaction
193
Ways neurotransmitters are removed
breakdown by enzymes, reuptake by presynaptic terminal, reuptake by nearby glial cell, uptake by post-synaptic terminals, diffuse out of synaptic cleft, combination of those
194
Two kinds of neural activity
excitatory and inhibitory
195
Excitatory neural activity
causes another neuron to be more likely to fire
196
Inhibitory neural activity
causes another neuron to become hyperpolarized, making it less likely to fire
197
Agonists
drugs and poisons that increase the activity of one or more neurotransmitters
198
Antagonists
drugs and poisons that decrease the activity of one or more neurotransmitters
199
Acetylcholine (ACh)
involved in both learning and memory and muscle movement
200
GABA
main inhibitory neurotransmitter
201
Glutamate
main excitatory neurotransmitter
202
ACh receptor subtypes
nicotinic and muscarinic
203
ANS function
controls involuntary activity; defined as efferent systems; motor neurons from both divisions innervate smooth muscle, cardiac, glands
204
Differences between somatic and autonomic nervous systems
effectors, efferent pathways, target organ responses to neurotransmitters
205
Dual innervation
almost all visceral organs are served by both divisions, but they cause opposite effects
206
Role of the sympathetic division
mobilizes the body during activity; promotes adjustments during exercise or when threatened
207
Role of the parasympathetic division
promotes maintenance activities and conserves body energy
208
Origin of sympathetic fibers
thoracolumbar region of the spinal cord
209
Length of sympathetic fibers
short preganglionic and long postganglionic
210
Location of sympathetic ganglia
close to spinal cord
211
Origin of parasympathetic fibers
brain and sacral spinal cord (craniosacral)
212
Length of parasympathetic fibers
long preganglionic and short postganglionic
213
Location of parasympathetic ganglia
in visceral effector organs
214
Sympathetic pathway
preganglionic neuron secretes ACh, receptor is nicotinic; postganglionic neuron secretes Norepinephrine, receptor is adrenergic
215
Parasympathetic pathway
preganglionic neuron secretes ACh, receptor is nicotinic; postganglionic neuron secretes ACh, receptor is muscarinic
216
Sympathetic nervous system exceptions
sweat glands postganglionic neuron secretes ACh to muscarinic receptors; adrenal glad doesn't have a second neuron in the chain, epi and norepi are directly secreted to bloodstream
217
Cholinergic receptors
nicotinic or muscarinic; named after drugs that bind to them and mimic ACh effects
218
Nicotinic receptors
always stimulatory, on all postganglionic neurons, ionotropic
219
Muscarinic receptors
can be inhibitory or excitatory; found on effector cells stimulated by parasympathetic postganglionic neurons; metabotropic ("G-protein coupled"): sets off an intracellular signaling cascade
220
Adrenergic receptors
found on effector cells stimulated by sympathetic postganglionic neurons; 2 types--alpha and beta; effects of neurotransmitter depends on what receptor predominates on the target organ; metabotropic
221
Heart sympathetic effect
beta 1 receptors; increases force of contraction, increases heart rate
222
Heart parasympathetic effect
muscarinic receptors; decrease force of contraction, decrease heart rate
223
Lungs sympathetic effect
beta 2 receptors; relaxes bronchial smooth muscle
224
Lungs parasympathetic effect
muscarinic receptors; contracts bronchial smooth muscle
225
GI tract and glands sympathetic effect
alpha 1 receptors; decrease motility, decreases secretion, decreases blood flow
226
GI tract and glands parasympathetic effect
muscarinic receptors; increase motility, increases secretion
227
Eyes sympathetic effect
alpha 1 receptors; dilate pupil
228
Eyes parasympathetic effect
muscarinic receptors; constrict pupil
229
Blood vessels sympathetic effect
alpha 1 receptors: constriction of blood vessels in most of body; beta 2 receptors: dilation of blood vessels that supply skeletal muscle
230
Exception to dual innervation
blood vessels
231
External genitalia sympathetic effect
alpha 1 receptors; cause vasoconstriction, ejaculation of semen and reflex contraction of vagina
232
External genitalia parasympathetic effect
muscarinic receptors; cause vasodilation, erection of penis or clitoris
233
Synergistic ANS effect
external genitalia, cooperative effect--both occur
