116 Exam 3 Flashcards
(117 cards)
1
Q
Central Nervous System
A
brain and spinal cord
2
Q
cluster of nerve cell bodies in CNS
A
nucleus
3
Q
peripheral nervous system
A
all neurons not a part of the brain and spinal cord
4
Q
cluster of nerve cell bodies in PNS
A
ganglion
5
Q
Neurons
A
cells that send and receive chemical and electrical signals to and from other neurons throughout the body
present in all animals (except sponges)
conduct nerve impulses
structural and functional unit of nervous system
6
Q
soma
A
cell body, contains nucleus and organelles
7
Q
dendrites
A
extension of plasma membrane
receive signals
8
Q
axons
A
extension of plasma membrane
send signals
hillock located near cell body
9
Q
synaptic terminal
A
end of axon, contains neurotransmitters
conducts signal across synapse
10
Q
glia
A
support cells in NS
11
Q
oligodendrocytes
A
form myelin sheath in CNS
12
Q
Schwann cells
A
form myelin sheath in PNS
13
Q
astrocytes
A
stem cell to produce more glial cells and neurons
provide metabolic support
14
Q
microglia
A
remove cellular debris
15
Q
radial glia
A
form tracks for neuronal migration in embryos
stem cell to produce more glial cells and neurons
16
Q
sensory neuron
A
detects info from outside world or internal body conditions
aferent (to CNS)
17
Q
motor neuron
A
sends signals to elicit response, move muscles, etc.
eferent (away from CNS)
18
Q
inter neuron
A
connects neurons to each other
19
Q
reflex arc
A
simplest pathway for signal, sensory neuron straight to motor neuron without interpretation by brain (only spinal cord)
20
Q
Membrane potential
A
difference in charge inside and outside cell
separated by cell membrane
caused by differing ion concentrations
polarized
21
Q
resting membrane potential
A
when neurons not sending signals
- 70 mv inside the cell
- ions on inside arrayed to + ions on outside
22
Q
3 factors contributing to resting potential
A
- Na+/K+ ATPase
3 Na+ out for every 2 K+ in, makes cell more - - Ion-specific channels (passive movement)
K+ channels open more frequently at resting potential
Membrane more permeable to K+ - Negatively charged molecules (proteins, DNA) more abundant inside cell
23
Q
Electrochemical gradient
A
combined effect of electrical and chemical gradients
24
Q
chemical gradient
A
charges are equal but more of one ion (K+) on one side than the other
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electrical gradient
same ion (K+) concentration on both sides, but one side more charged than the other
26
What causes changes in membrane potential?
Changes in level of polarization
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Depolarization
cell membrane becomes less negative relative to surroundings
| gated channels open to allow Na+ into cell and make membrane potential more positive
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Hyperpolarization
cell membrane becomes more -
| K+ moves out of cell
29
What types of cells are excitable?
Muscle and nerve cells but all cells have a membrane potential
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excitable
have capability to generate electrical signals
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voltage-gated
open/close in response to voltage changes
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ligand-gated
open/close in response to chemicals/ligands
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Graded Potentials
depolarization or hyperpolarization
varies depending on strength of stimulus
occur locally, spread a short distance, then die out
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Graded hyperpolarization steps
gated K+ channels open, K+ diffuses out, membrane potential becomes more -
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Graded depolarization steps
gated Na+ channels open, Na+ diffuses in, membrane potential becomes more +
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threshold potential
-55 mv
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Action Potential
all or nothing depolarization
| when graded potentials sum to -55 mv AP triggered
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steps in action potential
1. resting state: -70 mv, K+ closed and Na+ AG closed but not IG
2. Threshold: AG of Na+ opens, Na+ flows in while K+ stays in
3. Depolarization: cell becomes more + as Na+ flows in
4. Repolarization: IG for Na+ closes channel at +35 mv, K+ channel opens and it flows out making MP - again
5. Undershoot: out flow of K+ makes MP too negative, both AG and IG for Na+ closed for refractory period
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Refractory Period
while IG of Na+ closed, neuron cannot respond to another stimulus
places limit on frequency of action potentials and prevents AP moving backwards
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Why do K+ channels open slower than Na+?
prevents their effects negating each other
| key evolutionary event
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Conduction of signals
Na+ enters and reaches threshold potential at axon hillock
Triggers opening of voltage-gated Na+ channels there
depolarizes area near axon terminus
sequential opening of Na+ channels conducts wave of depolarization from axon hillock to terminus
Gated Na+ channels prevent backward movement
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What factors affect signal speed?
```
axon diameter (broader is faster since less resistance)
myelinated faster than unmyelinated
```
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nodes of ranvier
gaps between myelin sheaths
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saltatory conduction
action potential jumps (flows thru cytosol) to next node of ranvier
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Synapses
junction where nerve terminal meets a neuron, muscle, or gland
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electrical synapse
electric charge flows freely from one cell to another
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chemical synapse process
1. presynaptic cell contains vesicles of neurotransmitter
2. exocytosis releases neurotransmitters into synaptic cleft
3. diffuse across cleft, bind to channels/receptors in postsynaptic cell
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Excitatory vs. Inhibitory Synaptic Potential
```
EPSP = brings cell closer to TP, depolarization
IPSP = brings cell further from TP, hyperpolarization
```
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What can cause a synaptic signal to end?
neurotransmitter broken down by enzymes or transmitted back to presynaptic cell for reuse
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Temporal summation
impulses are one after the other, sum to TP
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spatial summation
impulses occur at the same location/time
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6 classes of neurotransmitters
```
acetylcholine
biogenic amines
amino acids
neuropeptides
gaseous neurotransmitters
dopamine
```
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acetylcholine
one of most widespread NT
released at neuromuscular junctions
excitatory in brain and skeletal muscles
inhibitory in cardiac muscles
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biogenic amines
abnormally high or levels associated with various diseases (Parkinson's, depression, schizophrenia)
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amino acids
glutamate is most widespread excitatory NT
| GABA (gamma aminobutyric acid) is most widespread inhibitory NT
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neuropeptides
AKA neuromodulators
can alter response of postsynaptic neuron to other NTs
opiate peptides, oxytocin, enkaphalin
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gaseous neurotransmitters
not contained in vesicles, produced locally as needed
short acting, influence other cells by diffusion
ED drugs increase/mimic action of NO on smooth muscle
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dopamine
generally excitatory, inhibitory at some sites
widespread in brain and affects sleep, mood, learning
secreted by both CNS and PNS
too little = Parkinson's, too much = schizophrenia
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How can the same signal cause a different response in one cell than another?
Different signal transduction pathways
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Hemolymph
blood(vessel fluid) and interstitial fluid mixed in one large compartment, OPEN circulatory system
nutrients/waste exchanged thru diffusion between body cells and hemolymph
less O2 needed so energetically inexpensive
circulation becomes more efficient as activity increases
no selective delivery to different tissues
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closed circulatory systems
physical separation between blood and interstitial fluid
larger, more active animals require higher blood pressure to get blood to all cells
earthworms, cephalopods, vertebrates
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blood
fluid connective tissue
cells, cell fragments, dissolved nutrients, proteins, gases, etc. dissolved in water
cellular components (RBC w/ no nucleus) wear out and are constantly replaced
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Where are erythrocytes and leukocytes made?
pluripotent stem cells in red bone marrow
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4 Components of blood
plasma - water and solutes, buffer, water balance, immune cell transport
erythrocytes - RBC, use hemoglobin to transport O2
leukocytes - WBC, defend body from infection and disease
platelets/thrombocytes - formation of blood clots, fibrin precipitation
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common blood features between animals
blood distributed thru vessels
at least one muscular, contractile heart
transports dissolved solutes
contains disease-fighting cells/molecules
can be adjusted to meet metabolic demands
capacity to heal self when wounded (clots)
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single circulation
fish
single atrium collects blood, single ventricle pumps blood out
arteries > gills to exchange O2 and CO2 > other arteries to tissues
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3 - chambered heart
amphibians rely on lungs and highly permeable skin to exchange gases
heart pumps blood to pulmocutaneous (skin and lungs) or systemic circulation
2 atria collect blood, one ventricle pumps it out
internal structure keeps O2 and non-O2 blood mostly separate but mixing does occur
low/medium pressure used to minimize pressure in lung tissue
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double circulation
crocodiles, birds, mammals
2 distinct circuits for systemic and pulmonary circulation
2 atria and 2 ventricles
different pressures in different circuits
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myogenic hearts
electrically excitable, generate own action potential
| nervous input can increase or decrease rate
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neurogenic heart
require regular electrical impulses from nervous system
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cardiac cycle
events that produce a single heartbeat
| frequency is heart rate/pulse
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diastole
atria contract, ventricles fill, lowest BP
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systole
ventricles contract, blood pushed out of heart, highest BP
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cardiac output
volume of blood (L) pumped into systemic circulation per minute
depends on heart size and pulse
stroke volume/pulse(min)
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sinoatrial node
collection of modified cardiac cells that spontaneously and rhythmically produce their own action potentials
act as pacemaker
affected by exercise, nerves, hormones, body temp
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atrioventricular node
conducts impulse from sinoatrial nodes to ventricles causing them to contract
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arteries
take blood away from heart
| layers of smooth muscle and connective tissue around smooth endothelium
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arterioles
smaller arteries, dilate or constrict to control blood flow to tissues
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capillaries
site of gas and nutrient/waste exchange
single-celled layer of epithelium on basement membrane
continuous(smooth) or fenestrated (holes)
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capillary exchange process
blood enters under high BP on arteriole end
fluid forced out by pressure but not RBC or large proteins
most of fluid that leaves recaptured at venule end using low pressure and osmotic force of large proteins
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venules
small, thin extensions of capillaries
82
lymphatic system
collects fluid that is not recaptured by capillaries and returns it to blood
83
veins
conduct blood back to heart
thinner and less muscular than arteries
lower BP
84
What helps veins get blood back to the heart?
smooth muscle contractions help propel blood
| valves in veins squeezed by skeletal muscles
85
Resistance
tendency of blood vessels to slow down blood flow
based on vessel radius and length and blood viscosity
changing R is major mechanism in controlling blood flow to a region
86
What is the most important factor in blood resistance?
vessel radius
87
stroke volume
amount of blood heart ejects at each beat
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arterial blood pressure
tells how hard heart is working and arteriole dilation level
| Cardiac Output * Total Peripheral Resistance
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epinephrine
hormone from adrenal gland that increases cardiac output by increasing stroke volume and/or pulse
90
baroreceptors
stretch receptors located in certain arteries
detect blood pressure and send it to brain
causes changes in vasodilation and constriction
91
cardiovascular disease
conditions affecting heart and blood vessels
| most deaths in the US each year
92
systemic hypertension
high blood pressure
caused by aging, smoking, obesity, etc.
treated with diet, exercise, drugs
93
pulmonary hypertension
results in congestive heart failure
| blood backs up into lungs, pressure rises, forces fluid into lungs
94
atherosclerosis
systemic hypertension causes damage leading to plaque buildup on interior artery walls, can block lumen
95
plaque
cholesterol buildup
96
myocardial infarction
heart attack
coronary blood vessels blocked by plaque
regions of cardiac muscle die when blood supply cut off, don't regenerate
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cardiac angiography
can detect narrowing of coronary vessels
98
balloon angioplasty
can widen lumen of narrowed vessels
99
coronary bypass
takes blood vessel from another part of body and uses it to replace blocked coronary artery
100
Gas solubility and temperature/pressure
as temp increases, gas solubility decreases
| as pressure increases, gas solubility increases
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nose and mouth
air is warmed and humidified
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pharynx
food and air mix
103
larynx
vocal cords
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trachea
leads from pharynx to bronchi
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glottis
opening to trachea, protected by epiglottis
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bronchioles
surrounded by circular muscle to dilate/constrict passage
107
alveoli
site of gas exchange
one cell thick
coated with extracellular fluid for gases to dissolve
surfactant prevents them from collapsing
108
pleural sac
encases each lung
| 2 layers with fluid in between that lubricates and adheres them together
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Negative Pressure Ventilation
mammals, birds, reptiles
| lung volume expands creating negative pressure and drawing air in
110
tidal ventilation
mammals
inhalation - intercostoals contract to bring chest wall out, diaphragm contracts and drops down to increase V and bring air in
exhalation - intercostals and diaphragm relax, V decreases and air is pushed out
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chemoreceptors
in aorta
| monitor pH and CO2 and O2 levels
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Breathing rate increases if:
O2 levels fall
| pH drops due to increased acid production from anaerobic metabolism or CO2 from aerobic production
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How is CO2 carried in the blood?
66% as HCO3- made reversibly by carbonic anhydrase in RBC
25% bound in hemoglobin
7-10% dissolved in plasma and RBC
114
Respiratory pigments
proteins with one or more metal ions with high affinity for O2, bind non-covalently and reversibly
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hemoglobin
respiratory pigment with iron as metal
4 protein subunits, each with heme unit
binds 4 O2 per molecule
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emphysema
extensive lung damage
reduces elastic quality of lungs, total SA of alveoli
reduced lung function and blood O2 levels
117
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