test 2 Flashcards
1
Q
What are the 4 methods of heat transfer?
A
Conduction
convection
thermal regulation
evaporation
2
Q
Conduction
A
loss or gain
3
Q
convection
A
loss or gain
4
Q
thermal regulation
A
loss or gain
5
Q
evaporation
A
loss
6
Q
conduction rate of transfer determined by
A
- Temperature gradient
- Distance between core and environment
- Conductivity of the material between core and environment
7
Q
convection rate of transfer determined by
A
- Temperature gradient
- Air/fluid speed
- Shape/diameter of body parts
8
Q
involves contact between solid objects to move heat
A
conduction
9
Q
wave length _____ as temperature ____
A
Decreases, increases
10
Q
A potential mechanism for cooling without water loss
A
thermal radiation
11
Q
thermal radiation Rate of heat transfer determined by?
A
Surface temperature
Emissivity of the surface
12
Q
Radiation may be _____, ______, or _____
A
absorbed, reflected or pass through
13
Q
Heat moves from ____ temperature to ____ temperature
A
high temperature to low temperature
14
Q
Objects receiving the heat _____ in temperature, objects losing heat _____ in temperature
A
increase, decrease
15
Q
Thermal equilibrium occurs when?
A
both objects are at the same temperature and there is no net movement of heat
16
Q
Animals may gain and lose heat _____
A
simultaneously
17
Q
Transfer of heat between neighboring molecules due to a temperature gradient
A
conduction
18
Q
Transfer of heat through a substance due to visible movement of the substance
A
convection
19
Q
Much faster than conduction
A
convection
20
Q
Highly effective cooling mechanism
A
evaporation
21
Q
Conversion of body water from the skin and respiratory tract to gas requires substantial amounts of heat energy
A
evaporation
22
Q
warmed by the metabolic production of heat
A
Endothermy
23
Q
maintenance of a relatively constant body temperature
A
Thermoregulation
24
Q
Environmental temperature
A
Determines metabolic rate and therefore how much food is required
25
Body temperature
| 4
- Regulates tissue function
- Balance of heat input versus heat output
- Heat input: metabolic heat production, from the environment, conduction, convection, radiation
- Heat output: conduction, convection, radiation, evaporation
26
Poikilotherms are also called ____
ectotherms
27
fish, reptiles, amphibians are examples of ?
ectotherms
28
Body temperature is dependent on environmental temperature
ectotherms
29
mammals, birds, some insects
homeotherms
30
Can also alter behavior to influence heat dissipation
homeotherms
31
Thermoregulate by physiological means
homeotherms
32
Mammals maintain their body temperatures within a very narrow range called
“Set point”
33
Skin thermoreceptors: (3)
- Skin in contact with environment
- Skin temperature changes before core temperature
- “warning system”- modify the set temperature to trigger a thermoregulatory response before core temperature changes
34
Core thermoreceptors: (3)
- Hypothalamus (brain)
- Receive inputs from skin thermoreceptors
- Generate the response
35
How is body temperature monitored and regulated?
skin and core thermoreceptors
36
Thermoneutral zone:
the range of environmental temperatures where animals can maintain core body temperature without an increase in metabolic rate
37
DOES NOT REQUIRE ENERGY THEREFORE DOES NOT AFFECT THE METABOLIC RATE (energy req’t)
Insulation
38
Vasomotor responses
- (physiological)
- Vasoconstriction/vasodilation to alter blood flow to the skin
- Insulation
39
Postural responses
- (behavioral)
- Controlling amount of surface area exposed to ambient temperatures
- Insulation
40
Erection or compression of hair (pilomotor response) or feathers (ptilomotor response)
- (physiological)
- Greater erection = greater insulation = greater resistance to heat loss
- Insulation
41
Resistance to heat loss through conduction, convection and radiation
Insulation
42
Body temperature maintained by ?
mediating the degree of insulation
43
Width of TNZ is determined by the extent to which the ?
animal can mediate their insulation
44
Shivering
- (physiological)
- Uncoordinated contraction/relaxation of muscles
- ATP ultimately becomes heat
45
Non-shivering thermogenesis
-(physiological)
-Heat production without shivering
fat oxidation can occur quickly, but energy released directly as heat
-Primarily mammals and young birds
Cold-acclimated adults, hibernators, newborns
Brown adipose: high vascularity, large mitochondria, well innervated; uncoupling protein 1 expression
46
Below the thermoneutral zone
ATP requiring = INCREASED METABOLIC RATE
47
Responses to temperatures above the upper critical temperature
- Energy requiring processes- ↑ metabolic rate
| - Initiation of evaporative cooling
48
Energy requiring processes to increase evaporative loss =
INCREASE METABOLIC RATE
49
Sweating:
- in some mammals; sweat secreted to the surface of the skin
- (physiological)
50
Panting:
- increased rate of breathing
| - (physiological)
51
Gular fluttering:
- in birds; vibrating the floor of the oral cavity to increase airflow over mucous membranes
- (physiological)
52
Pyrogens (cytokines, prostaglandins) cause an _____ in the body’s “set-point”
increase
53
Pyrogens
- Trigger to conserve heat and produce more heat to reach new set point
- Shivering, vasoconstriction, piloerection, etc.
- Increase in body temperature
54
Three types of muscle
- cardiac
- Skeletal
- smooth
55
Skeletal muscle
- Striated muscle associated with voluntary movement
| - Contraction is regulated by the somatic nervous system
56
Cardiac muscle
- Striated muscle in the heart
| - Contraction regulated by the autonomic nervous system
57
Smooth muscle
- Muscle in blood vessels, visceral tissues
| - Contraction is regulated by the autonomic nervous system
58
3 layers of connective tissue membranes:
- Epimysium: layer of cells encasing entire muscle
- Perimysium: layer of cells encasing a bundle (fascicle) of muscle fibers (muscle cells)
- Endomysium: layer of cells encasing individual muscle fibers
59
Multi-nucleated =
each cell has more than one nucleus
60
Sarcoplasmic reticulum- surround _____
individual myofibrils
61
Sarcolemma =
- cell membrane of individual muscle fibers
- Plasma membrane
- Outer membrane of polysaccharide and collagen
- Invaginations = T-tubules
- Has acetylcholine receptors and ion channels
62
A strand of interacting proteins (actin + myosin) that runs parallel to the length of the muscle
Myofibrils
63
Repeating unit that forms the myofibrils =
sarcomere
64
sarcomere
- Contractile unit
- Each sarcomere shortens during muscle contraction
- Net effect = entire muscle fiber shortens
65
Individual sarcomeres separated by
Z-disks
66
sarcomeres Composed of ?
- myofilaments (proteins)
- Thick (myosin)
- Thin (2 actin chains, troponin, tropomyosin)
67
Thick filament
Myosin molecules arranged to have “head” and “tail” regions
68
Thin filament
- Actin chain
- Troponin
- Tropomyosin
69
Flexion
Decreases joint angle
70
Extension
Increases joint angle
71
Whole-muscle contraction
Distance between insertion (end of the muscle that attaches to the freely moving bone) and origin (end of muscle that attaches to the “fixed” bone in the joint) shortens
72
The sarcomere shortens because there is a ?
greater degree of overlap between the thick and thin filaments
NONE of the individual filaments changes in length
73
“Sliding filament theory”:
thick and thin filaments slide over each other, increasing the degree of overlap
74
Muscle contraction needs:
- ATP
- nerve impulse (acetylcholine)
- calcium
75
_____ is needed to separate actin from myosin from the previous contraction cycle
ATP
76
Myosin ATPase cleaves ______
| the energy is not used until calcium is present
ATP to ADP + Pi
77
_____ binds _____, allowing myosin to bind to actin
Calcium, troponin
78
The Pi group is released and the stored energy is used to
flex the myosin head, pulling the thin filament over the thick filament, towards the M-line
- Powerstroke
- ADP is eventually released
- Cycle repeats itself as ATP binds to the myosin head
79
Troponin
- Attached to actin filaments and tropomysin
| - Has a binding site for calcium, which influences how it interacts with tropomyosin
80
Tropomyosin
- No Ca2+ = blocks myosin binding site on actin
| - Ca2+ = moves off the myosin binding site on the actin
81
Ca2+ enters the cytoplasm due to
nerve stimulation
82
Excitation-Contraction coupling
- Relationship between membrane depolarization and contraction
- Link between nervous and musculoskeletal systems
83
T-tubules of the sarcolemma
- Membrane “dips” into the cytoplasm (sarcoplasma) perpendicular to the fibers
- Has ion channels
- Allows membrane depolarization to be “experienced” deep in the muscle fiber
84
Sarcoplasmic reticulum
- Surround each myofibril
- Sequester and release Ca2+ upon membrane (t-tubule) depolarization (Ach binding receptors on sarcolemma)
- Terminal cisternae- part of the SR near the t-tubules and store calcium ions
85
Membrane calcium channels
| 2 voltage-gated calcium channels
- T-tubules: DHPRs (dihydropyridine receptor)
| - Sarcoplasmic reticulum: RyR (ryanodine receptor)
86
ATP needed for:
- ATP binding to cross-bridge: myosin detaches from actin- prevent rigor mortis
- ATP hydrolysis: energy needed for the “power stroke”
- Drives the Ca2+ pump to return calcium to the sarcoplasmic reticulum
87
Twitch fibers
- generate action potentials
| - Most common
88
Classified based on myosin ATPase type (how fast myosin ATPase can cleave myosin; speed of contraction)
- I: Slow oxidative
- IIA: Fast oxidative glycolytic
- IIB/IIX: Fast glycolytic
89
What is a nervous system?
- A network of neurons and support (glial) cells
- Signals pass from sensory receptors/neurons, are integrated, new signals are generated and conducted through neurons to the effector cells
- A regulatory system
90
What does the nervous system help animals do?
-Regulate muscle contraction → regulate movement
Regulate secretions from glands → hormone, enzymes, saliva, etc.
Gather information about the external and internal environment → maintain homeostasis
Detect pain, pressure, chemical concentrations
Stimulate thirst, hunger and other survival mechanisms
91
CNS =
interneurons
- brain
- spinal cord
92
Continues caudally from the brainstem
spinal cord
93
Encapsulated by the vertebrae
spinal cord
94
spinal cord has 2 types of neural circuits
1. Local
- Sensory neurons, interneurons and motor neurons all in the same segment
- Control the output of that segment
- Primitive reflexes
2. Ascending/Descending
- Communication to/from the brain for higher integration
95
Peripheral nervous system
Any nervous tissue located outside of the brain and spinal cord
Sensing the environment
Activating tissue/organ responses
96
Peripheral nervous system, 2 key divisions:
Somatic
Autonomic
- Somatic
| - Autonomic
97
Central nervous system:
includes brain and spinal cord
98
Peripheral nervous system:
neurons going to and from the CNS
99
Afferent neurons:
conduct “signal” towards the CNS (sensory neurons)
100
Efferent neurons:
conduct “signal” away from the CNS (motor neurons)
101
Interneurons:
entirely within the CNS
102
Cell that is able to generate and propagate an electrical signal
neuron
103
4 key parts of the neuron:
Dendrites- Input
Cell body (soma)- Integration (processing)
Axon- Transmission
Pre-synaptic terminals (telodendrion)- Output
104
Neurons generate signals that are ____ and ____
fast, addressed
105
electrical signals are faster than _______ signals
hormonal
Potential to conduct 100 impulses per second
106
Cell body (stoma)
Nucleus containing
Processes emanate outwards
Organelles: mitochondria, golgi apparatus, endoplasmic reticulum (rough and smooth)
Active in protein synthesis (neurotransmitters)
107
Dendrites
- Short, branch repeatedly
- Dendritic spines
- Similar organelles to the stoma
108
Axon
Generally 1 per neuron
May or may not be myelinated
Contain mitochondria and smooth endoplasmic reticulum
109
Axon terminals
Branches off the end of the axon
Contain vessicles of neurotransmitters (made in stoma)
Axoplasmic transport
Site of neurotransmitter release
110
Glial cells
Cells in the nervous system that support neural function
111
Outnumber neurons ~10:1
Glial cells
112
Glial cells Different types (3)
Schwann cells (PNS)/Oligodendricytes (CNS): form myelin sheath (wrap around axons)
Astrocytes (CNS): metabolic support cells, intermediate between neuron and capillary
Microglial cells (CNS): immune function
113
Tract:
bundle of myelinated axons in the CNS
114
Nuclei:
groups of nerve cell bodies in the CNS
115
Grey matter:
cell bodies, synapses, unmyelinated axons
116
White matter:
- tracts of myelinated axons
| - Ascending and decending
117
outside of brain, inside of spinal cord
grey matter
118
inside of brain, outside of spinal cord
white matter
119
Nerve: a bundle of neuron axons in the peripheral nervous system
Cranial nerves
Spinal nerves
-a bundle of neuron axons in the peripheral nervous system
- Cranial nerves
- Spinal nerves
120
Ganglion:
a grouping of nerve cell bodies in the peripheral nervous system
121
Three key things contribute to the resting membrane potential:
Na+/K+ pump
Ion separation and ions will move toward their equilibrium (inside of the cell also has more proteins with a negative charge that cannot diffuse through the membrane, so even if K+ and Na+ move in and out to try to reach equilibrium, they
Differential membrane permeability (more K+ leakage channels and so K+ is more likely to reach equilibrium because it can move more freely through the membrane, so the resting membrane potential is closer to the K+ potential than the Na+ potential)
122
Resting membrane potential =
-65 mV
123
Na+ membrane equilibrium potential =
+58 mV
124
K+ membrane equilibrium potential =
-80 mV
125
Factors that maintain resting membrane potential:
- ions must pass through membrane channels or be actively transported
- Different membrane channels are permeable to different ions
- Selective permeability
- Membrane channels may open and close
- Not all channels are necessarily open/closed at the same time
- Different ions can move through the membrane at different times
126
Maintaining ion concentration differences at rest
- Maintained by the Na+/K+-ATPase pump
- 3 Na+ out, 2 K+ in
- Neither K+ or Na+ is in electrochemical equilibrium
127
Membrane is more permeable to ___ than ___
K+ than Na+
128
_______% of ATP produced in the brain from glucose is used for Na+/K+-ATPase pump function
50 – 70%
129
Something that _____ the membrane, makes the membrane potential greater than -65 mV
depolarizes
130
Something that _____ the membrane makes the membrane potential less than -65 mV
hyperpolarizes
131
What is an action potential?
Electrical signal generated by excitable cells due to voltage-dependent changes in membrane permeabilitie
132
action potential is triggered by ?
Triggered by depolarization (to ~-55 mV)
133
Action potentials are an _____ phenomenon
‘All or None’
134
Changes in ______ create action potentials
membrane permeability
135
Lidocaine =
local anaesthetic
136
Lidocaine “blocks”______channels
voltage-gated Na+
137
Downstream =
action potential possible
138
Upstream =
no action potential possible
139
Factors controlling action potential velocity (speed) (3)
axon diameter
temperature
mylionation
140
Factors controlling action potential velocity (speed)
Axon diameter
- ↑ action potential velocity with ↑ increased diameter
- More ion channels per unit length with increasing diameter = less resistance to ion flow into the axon = easier to depolarize
141
Factors controlling action potential velocity (speed)
Temperature
- Ion channels are temperature dependent
- Increasing temperature exponentially increases conduction velocity
- Warm blooded animals (vs. reptiles) can maintain a high conduction velocity without having large diameter neurons
142
Factors controlling action potential velocity (speed)
Myelination
- ↑ action potential velocity
- Action potential “jumps” from Node of Ranvier to Node of Ravier- Saltatory conduction
-Myelin = insulates the axon
No ions can move in/out portions of the axon where there is the myelin wrapped around
-Only need to depolarize the Node of Ranvier regions, which is a relatively small portion of the axon, therefore speed is much faster in myelinated axons than unmyelinated axon
143
What is a synapse? (5)
Contact between a neuron and another neuron or a neuron and its effector cell
Pre-synaptic neuron (axon)
Post-synaptic neuron (dendrite or cell body) OR a cell (ie. muscle)
Cells separated by the synaptic cleft
Communication occurs via neurotransmitters
144
What makes it a neurotransmitter?
Chemical compound present in the pre-synaptic terminal
Released upon stimulation (depolarization and calcium)
Interacts with the receptors on a post-synaptic cell
145
Properties of chemical synapses
| Fast =
ionotropic
146
Properties of chemical synapses
| Slow=
metabotropic
147
Properties of chemical synapses
Unidirectional
Uses neurotransmitters
Two classifications
- slow (metabotropic)
- fast (ionotrpoic)
Can be excitory (cause depolarization) or inhibitory (cause hyperpolarization)
148
Ionotropic (5)
receptor ligand-gated channel
Directly alter membrane permeability to ions (open/close ion channels)
Signal transduction
Fast
Excitory (depolarizes) and Inhibitory (hyperpolarizes) effects
149
Metabotropic
Receptor: G-coupled protein receptor
Produce a metabolic change in the post-synaptic cell (usually with secondary messengers)
Modulation of neuronal function
Slow
Excitory (indirect), Inhibitory (indirect) and other (cytoplasmic, gene expression, enzymatic) effects
150
Neurotransmitter released into
synaptic cleft
151
Neurotransmitter is synthesized in ________ cell
pre-synaptic cell
Stored in vesicles at either the active site or interior of axon terminal
152
Each vesicle contains _____ neurotransmitter molecules
~5,000
153
neuro transmitter Release requires _____ and ______
membrane depolarization and calcium influx
