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MCAT Review > Kaplan — Biology > Flashcards

Kaplan — Biology Flashcards

1
Q

Neuron

A

Specialized cell capable of transmitting electrical impulses and then translating those electrical impulses into chemical signals

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2
Q

Soma

A

Cell body of a neutron where the nucleus, ER, and ribosomes are located

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3
Q

Dendrites

A

Part of neuron which receive incoming messages from other cells

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4
Q

Axon hillock

A

Part of neuron that integrates the incoming signals and initiates the action potential if it reaches threshold

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5
Q

Axon

A

Long appendage that terminates inc lose proximity to a target structure

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6
Q

Myelin

A

Fatty membrane that prevents signal loss or crossing of signals

Increases the speed of the signal

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7
Q

Oligodendrocytes

A

Glial cells that produce myelin in the central nervous system

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8
Q

Schwann cells

A

Glial cells that produce myelin in the peripheral nervous system

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9
Q

Nodes of Ranvier

A

Exposed areas of the axon membrane where the signal will jump

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10
Q

Nerve terminal or synaptic bouton

A

Enlarged and flattened structure to maximize transmission of the signal to the next neuron

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11
Q

Neurotransmitter

A

Chemical that transmit information between neurons

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12
Q

Synaptic cleft

A

Space between the pre-synaptic and post-synaptic neurons in a synapse

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13
Q

Synapse

A

Nerve terminal, synaptic cleft, and pre-synaptic membrane

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14
Q

Nerve

A

Bundle of axons in peripheral nervous system

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15
Q

Tract

A

Bundle of axons in central nervous system

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16
Q

Ganglia

A

Cell bodies in peripheral nervous system

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17
Q

Nuclei

A

Cell bodies in central nervous system

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18
Q

Astrocyte

A

Nourishes neurons and forms the blood-brain barrier which controls the transmission of solutes from the bloodstream in nervous tissue

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19
Q

Ependymal cells

A

Line ventricles of brain and produce CSF

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20
Q

Cerebrospinal fluid

A

Physically supports the brain and acts as a shock absorber

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21
Q

Microglia

A

Phagocytic cells that ingest and break down waste products and pathogens in the central nervous system

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22
Q

Action potentials

A

All or nothing electrical impulses that travel down the axon to the synaptic bouton

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23
Q

Resting membrane potential

A

Net electric potential difference that exists across the cell membrane created by movement of charged molecules across that membrane

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24
Q

Potassium leak channels

A

Channels that allow the slow leak of potassium out of the cell

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25
Q

Equilibrium potential of potassium

A

-90 mV; point at which there is no more net movement of potassium

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26
Q

Equilibrium potential of sodium

A

60 mV

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27
Q

Na+/K+ ATPase

A

Continually pumps sodium and potassium back to where they started

More ATP is spent doing this than for any other purpose

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28
Q

Hyperpolarization

A

Lowering the membrane potential from its resting potential & making the neuron less likely to fire

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29
Q

Depolarization

A

Raising membrane potential from its resting potential & making the neuron more likely to fire

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30
Q

Summation

A

Additive effect of multiple signals

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31
Q

Temporal summation

A

Multiple signals are integrated during a relatively short period of time

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32
Q

Spatial summation

A

Additive effects based on the number and location of the incoming signals

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33
Q

Action potential sequence

A

(1) Na+ influx to reach threshold
(2) Rapid Na+ influx through voltage gated sodium channels to cause depolarization up to 35 mV
(3) Inactivation of sodium channels and delayed opening of potassium channels causes depolarization
(4) Delayed closing causes hyperpolarization
(5) Sodium-potassium pump returns to resting membrane potential

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34
Q

Three forms for voltage-gated sodium channels

A
  • Closed: before reaching threshold and after reversal of inactivation
  • Open: from threshold to approximately 35 mV
  • Inactive: from 35 mV to resting potential
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35
Q

Repolarization

A

Restoration of the membrane potential to the resting membrane potential

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36
Q

Absolute refractory period

A

No amount of stimulation can cause another action potential to occur

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37
Q

Relative refractory period

A

Greater than normal stimulation to cause an action potential because the membrane potential is lower than its resting membrane potential

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38
Q

Impulse propagation

A

Cause depolarization in surrounding regions and bring subsequent segments of the axon to threshold

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39
Q

Signal conduction and length

A

Increased length = slower conduction

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40
Q

Signal conduction and cross-sectional area

A

Greater cross-sectional area = faster conduction

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41
Q

Saltatory conduction

A

Signal “hops” from node of Ranvier to node of Ranvier

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42
Q

Synaptic transmission in a chemical synapse

A
  • NTs are stored in membrane bound vesicles in the nerve terminal
  • AP reaches the nerve terminal and opens voltage-gated calcium channels, allowing calcium to flow into the cell
  • Calcium triggers fusion of membrane-bound vesicles to the cell membrane
  • NTs are released into the cleft
  • NTs bind either to metabotropic or ionotropic receptors
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43
Q

Ways for removing NTs from synaptic cleft

A
  1. NTs can be broken down by enzymatic reactions
  2. NTs can be brought back into the pre-synaptic neuron using reuptake carriers
  3. NTs can diffuse out of the synaptic cleft
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44
Q

Sensory neuron

A

Transmits sensory information from sensory receptors to the spinal cord and brain

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45
Q

Motor neuron

A

Transmits motor information from brain and spinal cord to muscles and glands

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46
Q

Interneurons

A

Between other neurons

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47
Q

Central nervous system

A

Brain and spinal cord

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48
Q

White matter

A

Axons encased in myelin sheaths

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49
Q

Gray matter

A

Unmyelinated cell bodies and dendrites

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50
Q

Spinal cord regions

A

Cervical → thoracic → lumbar → sacral

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51
Q

Vertebral column

A

Protects spinal cord and transmits nerves at the space between adjacent vertebrae

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52
Q

Dorsal root ganglion

A

Cell body of sensory neurons

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53
Q

Peripheral nervous system

A

Made up of nerve tissue and fibers outside brain and spinal cord

31 pairs of spinal nerves + 12 cranial nerves

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54
Q

Somatic nervous system

A

Consists of sensory and motor neurons distributed throughout the skin, joints, and muscles

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55
Q

Autonomic nervous system

A

Manages the involuntary muscles associated with many internal organs and glands

Has two antagonistic branches

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56
Q

Parasympathetic nervous system

A

Branch of ANS that serves to conserve energy

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57
Q

Post-ganglionic NT for parasympathetic nervous system

A

Acetylcholine

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58
Q

Pre-ganglionic NT for parasympathetic nervous system

A

Acetylcholine

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59
Q

Structure of parasympathetic nervous system

A

Long pre-ganglionic neurons and short post-ganglionic neurons

60
Q

Effects of parasympathetic nervous system

A
  • Constricts pupils
  • Stimulates flow of saliva
  • Constricts bronchi
  • Slows heartbeat
  • Stimulates peristalsis and secretion
  • Contracts bladder
61
Q

Sympathetic nervous system

A

Branch of ANS that is activated by stress

62
Q

Post-ganglionic NT for sympathetic nervous system

A

Norepinephrine

63
Q

Pre-ganglionic NT for sympathetic nervous system

A

Acetylcholine

64
Q

Structure of sympathetic nervous system

A

Short pre-ganglionic neurons and long post-ganglionic neurons

65
Q

Effects of sympathetic nervous system

A
  • Increases heart rate
  • Redistributes blood to muscles of locomotion
  • Increases blood glucose concentration
  • Dilates the eyes
  • Releases epinephrine into bloodstream
66
Q

Monosynaptic reflex arc

A

Single synapse between the sensory neurons that receives the stimulus and the motor neuron that responds to it

67
Q

Knee-jerk reflex

A

Monosynaptic reflex arc

Patella of knee is hit, causing the stretch of tendon, leading to contraction of quadriceps of muscles

68
Q

Polysynaptic reflex arc

A

One interneuron between the sensory and motor neurons

69
Q

Withdrawal reflex

A

Polysynaptic reflex arc

Pulls away one leg in response to painful stimulus and extends the other leg to maintain balance

70
Q

Ampulla

A

Widest part of the Fallopian tube where fertilization occurs

71
Q

Acrosomal apparatus

A

Sperm that first comes into contact with secondary oocyte’s cell membrane forms a tubelike structure that extends to and penetrates the cell membrane

72
Q

Cortical reaction

A

Release of calcium ions in response to penetration of the sperm through the cell membrane

Increases the metabolic rate of the zygote and prevents fertilization by multiple sperm cells

73
Q

Fertilization membrane

A

Now depolarizer and impenetrable membrane

74
Q

Dizygotic (fraternal) twins

A

Fertilization of two different eggs released during one ovulatory cycle by two different sperm

Each zygote will implant in the uterine wall and have its own placenta, chorion, and amnion

75
Q

Monozygotic (identical) twins

A

Single zygote splits into two

Can be classified by the structures that they share

76
Q

Conjoined twins

A

When zygote division is incomplete, two offspring will be physically attached

77
Q

Cleavage

A

Rapid mitosis cell decisions of a zygote

Increase in N:C and surface area:volume ratios

78
Q

Indeterminate cleavage

A

Results in cells that can still develop into complete organisms

79
Q

Determinate cleavage

A

Results in cells with fates that are already determined

80
Q

Morula

A

Solid mass of cells

81
Q

Blastula

A

Hollow ball of cells with a fluid-filled inner cavity (blastocoel)

82
Q

Blastocoel

A

Fluid-filled inner cavity

83
Q

Blastulation

A

Formation of the blastula (hollow ball of cells)

84
Q

Blastocyst

A

Mammalian blastula that consists of two noteworthy cell groups (trophoblast and inner cell mass)

85
Q

Trophoblast cells

A

Surround the blastocoel and give rise to the chorion and later the placenta

86
Q

Inner cell mass

A

Protrudes into the blastocoel and gives rise to the organism itself

87
Q

Chorion

A

Extraembryonic membrane that develops into the placenta formed by trophoblasts

88
Q

Chorionic villi

A

Microscopic finger-like projection that penetrate the endometrium and originate from trophoblasts

89
Q

Umbilical cord

A

Connects the embryo to the placenta and consists of two arteries and one vein encased in a gelatinous structure

90
Q

Yolk sac

A

Supports the embryo until the placenta is functional and is the site of early blood cell development

91
Q

Allantois

A

Involved in early fluid exchange between the embryo and yolk sac

Remnants of the yolk sac and allantois form the umbilical card

92
Q

Amnion

A

Thin, tough membrane filled with amniotic fluid that surrounds the allantois

Serves as a shock absorber

93
Q

Gastrulation

A

Generation of three distinct cell layers

Begins with the invagination in the blastula

94
Q

Archenteron

A

Membrane invagination into the blastocoel

95
Q

Blastophore

A

Opening of the archenteron

Develops into the mouth in protostomes or anus in deuterostomes

96
Q

Ectoderm

A

Forms the epidermis, hair, nails, epithelium of nose & mouth, lens of eye, nervous system, inner ear

97
Q

Mesoderm

A

Musculoskeletal, circulatory, excretory systems

98
Q

Endoderm

A

Epithelial linings of digestive and respiratory tracts

Pancreas, thyroid, bladder, distal urinarytracts

99
Q

Induction

A

Ability of one group of cells to influence the fate of nearby cells

100
Q

Inducers

A

Diffuse from organizing cells to the responsive cells

101
Q

Neurulation

A

Development of the nervous system

102
Q

Notochord

A

Rod of mesodermal cells forms along the long axis of the organism like a primitive spine

Induces a group of overlying ectodermal cells to slide inward to form neural folds which surround a neural groove

103
Q

Neural tube

A

Gives rise to the central nervous system

Neural folds growth toward one another until they fuse into a neural tube

104
Q

Neural crest cells

A

At the tip of each neural fold

Forms the peripheral nervous system

105
Q

Teratogens

A

Substances that interfere with development, causing defects or even death of the developing embryo

106
Q

Specification

A

Cell is reversibly designated as a specific cell type

107
Q

Determination

A

Commitment of a cell to a particular function in the future

108
Q

Morphogen

A

Molecules that cause neighboring cells to follow a particular developmental pathway

109
Q

Differentiation

A

Process of a cell undertaking changes to develop into the determined cell type

110
Q

Stem cells

A

Cells that have not yet differentiated or that give rise to other cells that will differentiate

111
Q

Potency

A

Determines the tissues a particular stem cell can differentiate into

112
Q

Totipotent

A

Cells with the greatest potency

113
Q

Pluripotent

A

Cells that can differentiate into any cell type except for those found in the placental structures

114
Q

Multipotent

A

Cells that can differentiate into multiple types of cells within a particular group

115
Q

Responder

A

Cell that is induced by surrounding tissues

116
Q

Competent

A

Able to respond to the inducing signal

117
Q

Autocrine

A

Signals that act on the same cell that secreted the signal in the first place

118
Q

Paracrine

A

Signals that act on cells in the local area

119
Q

Juxtacrine

A

Cells directly stimulating receptors of an adjacent cell

120
Q

Encoring

A

Secreted hormones that travel through the bloodstream to a distant target tissue

121
Q

Growth factors

A

Peptides that promote differentiation and mitosis in certain tissues

122
Q

Reciprocal development

A

Development of one tissue by a precursor of another tissue will cause the development of the another tissue from its precursor

123
Q

Apoptosis

A

Programmed cell death

124
Q

Apoptotic blebs

A

Self contained protrusions formed when a cell undergoes apoptosis

125
Q

Apoptotic bodies

A

Formed from apoptotic blebs and can be digested by other cells

Prevents the release of potentially harmful substances into the extra cellular environment

126
Q

Necrosis

A

Process of cell death where the cell dies as a result of injury

127
Q

Regenerative capacity

A

Ability of an organism to regrow certain parts of the body

128
Q

Complete regeneration

A

Lost or damaged tissues are replaced with identical tissues

129
Q

Incomplete regeneration

A

Newly formed tissue is not identical in structure or function to the tissue that has been injured or lost

130
Q

Senescence

A

Biological aging

Can occur at the cellular or organismal level as these changes accumulate

131
Q

Telomeres

A

Ends of chromosomes

Shorten with aging

132
Q

Fetal hemoglobin (HbF)

A

Greater affinity for oxygen than maternal hemoglobin (HbA)

Also assists with the transfer (and retention) of oxygen into the fetal circulatory system

133
Q

Umbilical arteries

A

Carry blood away from the fetus toward the placenta

134
Q

Umbilical vein

A

Carries blood toward the fetus from the placenta

135
Q

Shunt

A

Redirect blood away from the liver and lungs during development because they are not commonly used

136
Q

Foramen ovale

A

One-way valve that connects the right atrium to the left atrium

Allows blood in the pulmonary circulation to be pumped by the systemic circulation directly

137
Q

Ductus arteriosus

A

Shunts leftover blood from the pulmonary artery to the aorta

Allows for blood to be pumped in the systemic circulation

138
Q

Ductus venosus

A

Bypasses the liver by shunting blood returning from the placenta into the inferior vena cava

139
Q

First trimester

A

Within 8 weeks, most organs have formed and embryo becomes known as the fetus

140
Q

Second trimester

A

Tremendous amount of growth for fetus

Face takes on a human appearance, move within amniotic fluid, toes and fingers elongate

141
Q

Third trimester

A

High transfer of antibodies to allow for protection

142
Q

Parturition

A

Vaginal birth caused by rhythmic contractions of uterine smooth muscle coordinated by prostaglandins and oxytocin

Three basic phases: cervix thins out and amniotic sac ruptures (water breaking), strong uterine contractions cause birth of the fetus, placenta and umbilical cord are expelled (afterbirth)

143
Q

Prostaglandins

A

Coordinate rhythmic contractions of uterine smooth muscle

144
Q

Oxytocin

A

Peptide hormone that coordinates rhythmic contractions of uterine smooth muscle

145
Q

Afterbirth

A

Expulsion of placenta and umbilical cord

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