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MCAT - Kaplan > Biology > Flashcards

Biology Flashcards

1
Q

A sodium influx would make the cell more ___ whereas a potassium influx would make the cell more __.

A

Positive; Negative

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2
Q

Na+ channels open during an action potential leading to ___

A

Depolarization

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3
Q

During depolarization (~+35) what voltage gated channels open to restore balance?

A

K+ / Potassium

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4
Q

When the action potential reaches “hyperpolarization” what does this mean and what channels (if any) are open at this stage?

A

-70 ; Na+ and K+ Leak Channels

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5
Q

The HPA axis is comprised of the Hypothalamus that secretes __ to activate the anterior pituitary and __ to activate the adrenal cortex.

A

CRF ; ACTH

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6
Q

Cortisol levels are part of the important __ feedback loop that regulates the HPA axis.

A

Negative

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7
Q

The HPG axis is comprised of the hypothalamus, pituitary and gonads. Some hormones are __.

A

GnRH, FSH and LH

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8
Q

On day 0 of the cycle GnRH levels rise this first results in ___ increasing through its release from the anterior pituitary and later __ levels rising.

A

FSH ; LH

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9
Q

On days 5-9 of the cycle estrogen uses __ feedback to prevent multiple ovulation.

A

negative

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10
Q

On days 10-13 of the cycle estrogen uses __ feedback to induce ovulation.

A

Positive

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11
Q

FSH is secreted by the anterior pituitary and its effect on the ovaries is ___.

A

follicle maturation of primary oocytes which can be detected by a rise in estrogen. estrogen als stops other follicles from maturing to prevent multiple ovulation.

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12
Q

LH is secreted by the anterior pituitary and it surges in preparation for __.

A

ovulation where the secondary oocyte ruptures.

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13
Q

In terms of myelin producing cells the CNS has __ and the PNS has __ cells.

A

oligodendrocytes ; schwann

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14
Q

The soma is the part where we can find __.

A

ribosomes

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15
Q

The dendrites are the part where they can receive __

A

messages

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16
Q

The axon hillock is the portion where we __

A

sum / integrate

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17
Q

A nerve is in the __ nervous system and consists of multiple neurons bound together. If clustered, it is referred to as a __

A

Peripheral ; Ganglia

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18
Q

A tract is in the __ nervous system and consists of multiple axons bound together. If clustered, it is referred to as a __

A

Central ; Nuclei

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19
Q

Astrocytes serve what purposes?

A

1) nourishment 2) blood brain barrier

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20
Q

Ependymal cells serve what purposes?

A

1) lining brain ventricles 2) producing cerebrospinal fluid

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21
Q

Microglia cells have a phagocytic effect in the __ nervous system,

A

central

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22
Q

The resting membrane potential is maintained by__

A

1) distribution of ions across the membrane 2) active transport

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23
Q

Excitatory neurons cause __

A

depolarization

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24
Q

Inhibitory neurons cause __

A

hyperpolarization

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25
Q

Temporal summation means that __

A

many in a small time leads to action potential

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26
Q

Spatial summation means that __

A

the number and location matters i.e. many inhibitory in one space –> inhibiton

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27
Q

The absolute refractory period is when no action potential can occur whereas a relative refractory period is __

A

greater than normal stimulation can lead to an action potential

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28
Q

The CNS is composed of __

A

brain, spinal cord

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29
Q

The PNS is composed of __

A

cranial, spinal, sensory

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30
Q

Afferent neurons are considered __ and follow the following signaling mode : sensor –> CNS.

A

Sensory

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31
Q

Efferent neurons are considered __ and follow the following signaling mode : CNS –> Effector.

A

Motor

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32
Q

The somatic nervous system is considered __ i.e. muscles whereas the autonomic is considered __ i.e. heart rate.

A

voluntary ; involuntary

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33
Q

A monosynaptic system consists of the following flow:

A

afferent presynaptic –> sensory –> motor –> efferent postsynaptic

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34
Q

A polysynaptic system consists of the following flow:

A

sensory –> INTERNEURON –> motor

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35
Q

Peptide hormones work indirectly and require a ___. They are __ acting and require __ carrier through the blood.

A

second messenger like cAMP ; short and transiently ; no

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36
Q

Steroid hormones work directly and require ___. They are __ acting and require __ carrier through the blood.

A

no secondary messengers as they can bind and make a conformational change like dimerization ; slow and longer lived ; a lipid soluble like albumin

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37
Q

Amino acid derivative hormones include T3, T4 which function like steroid hormones and __

A

catecholamines (epinephrine, norepinephrine) which function like peptide hormones

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38
Q

Catecholamines like epinephrine act like peptide hormones in that they are __ acting and require __.

A

faster, transient ; GPCR

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39
Q

Direct acting implies a hormone directly acts on a target tissue such as __

A

insulin

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40
Q

Tropic acting implies that a hormone requires __ and must secrete __. An example of this is GnRH and LH.

A

an intermediate ; another hormone

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41
Q

GnRH is secreted by the hypothalamus and does the following:

1) releases __ and __ from the anterior pituitary
2) targets __ (organ)
3) ultimately releasing __

A

FSH, LH ; gonads ; testosterone OR estrogen, progesterone

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42
Q

CRF is secreted by the hypothalamus and does the following:

1) releases __ from the anterior pituitary
2) targets __ (organ)
3) ultimately releasing __

A

ACTH ; adrenal cortex ; glucocorticoids

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43
Q

TRH is secreted by the hypothalamus and does the following:

1) releases __ from the anterior pituitary
2) targets __ (organ)
3) ultimately releasing __

A

TSH ; thyroid ; T3 & T4

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44
Q

Low dopamine levels in the hypothalamus does the following:

1) releases __ from the anterior pituitary
2) targets __ (organ)
3) ultimately releasing __

A

prolactin ; breast tissue ; n/a

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45
Q

GnRH is secreted by the hypothalamus and does the following:

1) releases __ from the anterior pituitary
2) targets __ (organ)
3) ultimately releasing __

A

growth hormone ; bone, muscle ; n/a

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46
Q

Recalling the FLAT PEG mnemonic where FLAT hormones are tropic and PEG hormones are direct acting what are the hormones in the mnemonic?

A

F: FSH ; L: LH ; A: ACTH ; T= TSH & P: Prolactin ; E: Endorphins ; G: Growth Hormones

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47
Q

The posterior pituitary secretes __ when there is high blood osmolarity. The immediate effect is increased water reabsorption in the collecting duct resulting in decreased plasma osmolarity.

A

ADH/ vasopressin (peptide hormone)

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48
Q

The adrenal glands secrete __ when there is low blood volume. The immediate effect is increased activity of the Na+/K+ pump in the nephron which results in increased blood volume.

A

Aldosterone (steroid hormones)

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49
Q

Somatostatin, in the pancreas, inhibits which two hormones __ and __

A

insulin ; glucagon

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50
Q

The adrenal medulla secretes catecholamines which increase __ and __ by bronchial dilation.

A

glycogenolysis ; metabolic rate

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51
Q

Increased blood sugar triggers __ release and glucose uptake by tissues. The sugar is then absorbed by cells, converted to glycogen and used for fatty acids or proteins.

A

insulin

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52
Q

Low blood sugar triggers __ release and glycogenolysis to increase blood sugar levels. The pancreatic alpha cells produce this hormone.

A

glucagon

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53
Q

Cortisol antagonizes insulin and is produced by the __ and stimulated by __.

A

adrenal cortex ; adrenal cortex

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54
Q

Parathyroid hormone increases plasma Ca2+ levels which thereby inhibit levels of PTH in a __ feedback mechanism.

A

negative

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55
Q

Calcitonin differs from PTH since it __ blood calcium levels.

A

lowers

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56
Q

The Hypothalamus - Pituitary - Gonadal Axis is important. __ release leads to progesterone (F), testosterone (M) and __ release leads to estrogen (f) and spermatogenesis (m)

A

LH ; FSH

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57
Q

The HPA axis consists of CRH which stimulates __ release in the anterior pituitary .

A

ACTH

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58
Q

The HPT axis consists of TRH which stimulates release of __ and eventually __ and __.

A

TSH ; T3 & T4

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59
Q

Endocrine signaling is a form of cell to cell communication where hormones are secreted __.

A

directly into the bloodstream

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60
Q

Paracrine signaling is a form of cell to cell communication where hormones are secreted __.

A

alongside/ adjacent through extracellular fluid

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61
Q

Juxtacrine signaling is a form of cell to cell communication where hormones are secreted __.

A

because of docking / touching

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62
Q

The Renin- Angiotensin- Aldosterone system is an example of __ feedback. Angiotensinogen –> renin leads to Angiotensin I and ACE leads to Angiotensin II which stimulates the release of aldosterone and increases blood pressure. The blood pressure inhibits angiotensinogen.

A

negative

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63
Q

The kidney uses three different process 1) filtration 2) secretion 3) reabsorption.

A

Filtration: moves solutes from blood into filtrate ; Secretion: move solutes blood to filtrate NOT Bowman ; Reabsorption: move solutes from filtrate to blood

64
Q

The renal corpuscle of the nephron generates __.

65
Q

The PCT reabsorbs __ and secretes ammonium and creatinine.

A

Na+, Cl-, K+, Water, Glucose, Amino Acids, Bicarbonate, Ca+, Phosphate

66
Q

The descending loop of henle reabsorbs __.

67
Q

The thin ascending loop of henle reabsorbs __

A

sodium and chloride

68
Q

The thick ascending loop of henle reabsorbs __

A

ammonium, sodium, chloride

69
Q

The distal convoluted tubule (DCT) reabsorbs __ and __.

A

sodium, chloride

70
Q

The collecting duct responds to ADH and aldosterone. It reabsorbs __ and __. It secretes ammonium, hydrogen ions and potassium.

A

sodium chloride ; water

71
Q

The blood passage goes from renal __ to renal __.

A

artery; vein

72
Q

Skin can exhibit cooling effects through __ and __

A

vasodilation and sweating

73
Q

Skin can exhibit warming effects through __ , piloerection, fat insulation and shivering.

A

vasoconstriction

74
Q

The stratum basale of the epidermis contains __

A

keratinocytes

75
Q

The dermis contains sensory endings such as nerve ends for pain Meissener for __ and Ruffini __ and Pacinian __.

A

light touch ; stretch ; vibration and pressure

76
Q

The hypodermis comprises fat and connective tissues and has an important role of __

A

connecting the skin to the rest of the body

77
Q

There is pH regulation with bicarbonate. If blood pH is high then the levels of bicarbonate in the urine are __.

78
Q

Fertilization occurs with the help of __ enzymes. The __ reaction then prevents additional sperm from fertilizing an egg.

A

acrosomal ; cortical

79
Q

Indeterminate cleavage means that a cell can become __ whereas determinate cleavage means that a cell can become __.

A

any cell ; specific cell

80
Q

Morula

A

Mass of cells (early)

81
Q

Blastula

A

forms the placenta

82
Q

Chorion

A

mom and fetal blood

83
Q

Allantois

A

fluid exchange

84
Q

Amnion

A

amniotic fluid

85
Q

Germ Layer (Ectoderm)

A

integument ; epidermis, hair , nails, mouth, nervous system and lens of eye

86
Q

Germ Layer (Mesoderm)

A

musculoskeletal, circulator, excretory systems, gonads, muscular + connective tissues, adrenal cortex.

87
Q

Germ Layer (Endoderm)

A

epithelial lining in respiratory and digestive system, thyroid, bladder, distal urinary

88
Q

Neurulation occurs in three main steps. 1) the notochord induces __ to form neural folds 2) the neural folds fuse to form __ (CNS) 3) tip of neural fold has neural crest which becomes the __, melanocytes , and calcitonin producing cells.

A

ectodermal cells; neural tube ; PNS

89
Q

Teratogens can cause defects or the death of the embryo. What are examples of teratogens?

A

alcohol, drugs, environmental chemicals, viruses, bacteria

90
Q

Determination of cells means that cells commit to __. Differentiation indicates changes due to __.

A

a cell lineage ; transcription

91
Q

Totipotent stem cells

A

all cell types including germ layer, placenta

92
Q

Pluripotent stem cells

A

all germ layers and derivatives

93
Q

Multipotent stem cells

A

only a subset of cell types

94
Q

Signaling: Paracrine

A

local cells not physically / directly

95
Q

Signaling : Juxtacrine

A

directly simulates adjacent cells

96
Q

Inducers release __ to promote __ of a competent responder.

A

factors ; differentiation

97
Q

The Milestones of embryogenesis

A

morula –> blastula –> gastrula

98
Q

The umbilical ARTERY carries __ blood from fetus to placenta. Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin.

A

deoxygenated

99
Q

The umbilical VEIN carries __ blood from the placenta to the fetus. Fetal hemoglobin has a higher affinity for oxygen than adult hemoglobin.

A

oxygenated

100
Q

Three Shunts of Fetal Circulation : Foramen Ovale , Ductus Arteriosus, Ductus Venosus

A

1) Foramen Ovale- right atrium to left atrium bypassing lungs
2) Ductus Arteriosus- pulmonary artery to aorta bypassing lungs
3) Ductus Venosus - umbilical vein to inferior vena cava ; bypassing liver

101
Q

During the first trimester __ occurs

A

organogenesis

102
Q

During the second trimester __ occurs

A

tremendous growth, movement begins, face of human and digits elongate

103
Q

During the third trimester __ occurs

A

rapid growth, brain development, transfer of antibodies to fetus

104
Q

During birth __ occurs

A

cervix thins, amniotic sac ruptures, uterine contractions due to oxytocin and prolactin

105
Q

The mitochondria is unique in that it is semi-autonomous. Therefore it is able to replicate via __ __ and is an example of extracellular inheritance.

A

binary fission

106
Q

The proton-motive force is established by the mitochondria. Specifically, the __ __ to the intermembrane space.

A

mitochondrial matrix

107
Q

Red blood cells are unique in that they contain no __

A

organelles

108
Q

Microfilaments

A

actin, cytokinesis

109
Q

Microtubules

A

tubulin, kinesin and dynein

110
Q

Intermediate Filaments

A

filamentous ; keratin, desmin, lamin

111
Q

Epithelial

A

underlying connective tissue (basement membrane) ; kidney nephron, liver hepatocytes etc.

112
Q

Obligate anaerobes are only anaerobic and have no way to use O2, but facultative anaerobes can function __

A

with or without oxygen

113
Q

Aerotolerant anaerobes

A

tolerate the presence of oxygen in the environment , but cannot use oxygen for metabolism.

114
Q

Gram Positive Bacteria

A

turn purple ; thick cell wall

115
Q

Prokaryotic ribosomes are __ and __ but eukaryotic ribosomes are 40s and 60s.

A

30s and 50s

116
Q

Episomes are plasmids that __

A

integrate into the genome

117
Q

Bacterial Genetic Recombination (conjugation):

A

transfer of genetic material from one bacterium to another

118
Q

Bacterial Genetic Recombination (transduction):

A

transfer via a bacteriophage vector

119
Q

Bacterial Genetic Recombination (transposons):

A

insert or remove themselves from genome

120
Q

Viroids are plant pathogens which are comprised of __. Prions trigger protein misfolding.

A

small circles of complementary DNA

121
Q

The lytic life cycle of a bacteriophage is when it is __ and new virions will continue until the cell lyses.

122
Q

The lysogenic cycle is when it is in a __.

123
Q

Penetrance

A

proportion of population with genotype who express the phenotype

124
Q

Expressivity

A

varying phenotypic manifestations of the same genotype

125
Q

Founder effect leads to __

A

homozygous genotypes incr.

126
Q

Genetic leakage is the flow of genes between _

A

species thru hybrid offspring

127
Q

Missense Mutation

A

substitution of one amino acid for another

128
Q

Nonsense Mutation

A

substitutes a stop codon for amino acid

129
Q

Recombination Frequency

A

likelihood of two alleles sep. crossing over in mitosis
1 map unit = 1% recombination frequency
determine % of genes furthest

130
Q

Hardy Weinberg must meet the following conditions

A

1) large population
2) no mutations
3) mating is random
4) no migration into/out of
5) genes equally successful at being reproduced

131
Q

p2+ 2pq+1^2=1

A

p^2=TT
2pq= Tt
q^2=tt
p^2+2pq = frequency dominant

132
Q

Punctuated Equilibrium

A

slow with bursts of evolutionary activity

133
Q

G1: Pre Synthetic Gap

A

incr. size, create organelles

proper complement of DNA to progress to S stage

134
Q

S: Synthesis of DNA

A

replicate genetic material so each daughter cell has identical copies
2 identical chromatids per chromosome per chromosome . Ploidy 2x

135
Q

G2: Postsynthetic Gap

A

checkpt. of enough organelles and cytoplasm for 2 cells ; checks for any errors to avoid passing to progeny

136
Q

M: Mitosis

137
Q

cyclins bind __ to phosphorylate transcription factors thus transcription of genes for the next stage occurs

138
Q

Prophase

A

chromosomes condense, form spindle

139
Q

Metaphase

A

gather at metaphase plate

140
Q

Anaphase

A

sister chromatids separate and migrate

141
Q

Telophase

A

chromosome decondenses , spindle breaks, nucleoli reappear, nuclear membrane reforms, 2 daughter cells

142
Q

Meiosis occurs in gametocytes with __ round of replication and __ rounds of division (reductional and equatorial).

143
Q

Meiosis I: Prophase

A 
homologs intertwine (synapsis) 
4 chromatids (tetrade) and cross over 
accounts for law of independent assortment
144
Q

Meiosis I: Metaphase

A

homologous chromosomes line up on opposite sides of metaphase plate

145
Q

Meiosis I: Anaphase I

A

pulled to opposite poles - accounts for Mendel’s Law of Segregation

146
Q

Meiosis I: Telophase I

A

chromosomes may or may not fully decondense and cell may enter interkinesis
2 haploid daughter cells by end

147
Q

Meiosis II

A

sister chromatids separated functionally similar to mitosis

4 haploid gametes by end

148
Q

Pathways of Sperm (SEVEN UP)

A 
seminiferous tubules 
epididymis 
vas deferens 
ejaculatory duct 
nothing 
urethra 
penis

(cowper glands clean out urine)

149
Q

Spermatogenesis

A

spermatogonia (diploid) –> 1 spermatocyte –> 2 spermatocyte (haploid) –> spermatids –> spermatozoa (4 total)

150
Q

Female Reproductive Pathway

A

ovaries –> peritoneal sac –> fallopian –> uterus

151
Q

Oogenesis

A

oogonia –> 1 oocyte arrested at prophase 1 –> 2 oocyte + polar body
after menstruation 1 primary oocyte to 2 oocyte monthly. The 2 oocyte stays at Metaphase II unless fertilized

152
Q

Steps of the Menstrual Cycle

A

1) Follicles mature (FSH, LH)
2) LH surge triggers ovulation
3) LH + FSH inhibition by estrogen secreted by corpus luteum
4) if no fertilization menses occurs (FSH + LH up and estrogen down)

153
Q

Menopause

A

ovaries stop producing estrogen and progesterone

FSH and LH levels rise

154
Q

hCG

A

an LH analog to maintain the corpus levels drop at the end of the first trimester

155
Q

nondisjunction

A

45, x instead of 46 xx

MCAT - Kaplan (6 decks)

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