(a) Fuctuation of gonadotropin levels: Fluctuating levels of pituitary gonadotropins (follicle-stimulating hormone and luteinizing hormone) in the blood regulate the events of the ovarian cycle. LH FSH (b) Ovarian cycle: Structural changes in the ovarian follicles during the ovarian cycle are correlated with (d) changes in the endometrium of the uterus during the uterine cycle. Mature Primary Secondary ovarian follicle Degenerating corpus luteum Ovulation Corpus luteum follicle follicle Follicular phase Luteal Ovulation (Day 14) phase (c) Fluctuation of ovarian homone levels: Auctuating levels of ovarian hormones (estrogens and progesterone) cause the endometrial changes of the uterine cycle. The high estrogen levels are also responsible for the LHVFSH surge in (a). Estrogens Progesterone (d) The three phases of the uterine cycle Menstrual: Shedding of the functional layer of the endometrium. Proliferative: Rebuilding of the functional layer of the endometrium. Secretory: Begins immediately after ovulation. Enrichment of the blood supply and glandular secretion of nutrients prepare the endometrium to receive an embryo. Blood vessels Endometrial glands Menstrual flow Functional- layer Basal layer Both the menstrual and proliferative phases occur before ovulation, and together they correspond to the follicular phase of the ovarian cycle. The secretory phase corresponds in time to the luteal phase of the ovarian cycle. Days ! 10 15 20 25 28 Menstrual Proliferative Secretory phase phase phase Figure 25.19 The menstrual cycle: structural and homonal changes. The time bar near the bottom of the figure, reading Days 1 to 28, applies to all four parts of this figure. Plasma hormone level Plasma hormone level
(a) Fuctuation of gonadotropin levels: Fluctuating levels of pituitary gonadotropins (follicle-stimulating hormone and luteinizing hormone) in the blood regulate the events of the ovarian cycle. LH FSH (b) Ovarian cycle: Structural changes in the ovarian follicles during the ovarian cycle are correlated with (d) changes in the endometrium of the uterus during the uterine cycle. Mature Primary Secondary ovarian follicle Degenerating corpus luteum Ovulation Corpus luteum follicle follicle Follicular phase Luteal Ovulation (Day 14) phase (c) Fluctuation of ovarian homone levels: Auctuating levels of ovarian hormones (estrogens and progesterone) cause the endometrial changes of the uterine cycle. The high estrogen levels are also responsible for the LHVFSH surge in (a). Estrogens Progesterone (d) The three phases of the uterine cycle Menstrual: Shedding of the functional layer of the endometrium. Proliferative: Rebuilding of the functional layer of the endometrium. Secretory: Begins immediately after ovulation. Enrichment of the blood supply and glandular secretion of nutrients prepare the endometrium to receive an embryo. Blood vessels Endometrial glands Menstrual flow Functional- layer Basal layer Both the menstrual and proliferative phases occur before ovulation, and together they correspond to the follicular phase of the ovarian cycle. The secretory phase corresponds in time to the luteal phase of the ovarian cycle. Days ! 10 15 20 25 28 Menstrual Proliferative Secretory phase phase phase Figure 25.19 The menstrual cycle: structural and homonal changes. The time bar near the bottom of the figure, reading Days 1 to 28, applies to all four parts of this figure. Plasma hormone level Plasma hormone level
Human Anatomy & Physiology (11th Edition)
11th Edition
ISBN:9780134580999
Author:Elaine N. Marieb, Katja N. Hoehn
Publisher:Elaine N. Marieb, Katja N. Hoehn
Chapter1: The Human Body: An Orientation
Section: Chapter Questions
Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...
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Question
In menstruation, the functional layer is shed from the endometrium. Explain the hormonal and physical factors responsible for this shedding. (See Figure 25.19.)
Transcribed Image Text:(a) Fuctuation of gonadotropin levels: Fluctuating
levels of pituitary gonadotropins (follicle-stimulating
hormone and luteinizing hormone) in the blood
regulate the events of the ovarian cycle.
LH
FSH
(b) Ovarian cycle: Structural changes in the ovarian
follicles during the ovarian cycle are correlated with
(d) changes in the endometrium of the uterus during
the uterine cycle.
Mature
Primary Secondary ovarian
follicle
Degenerating
corpus luteum
Ovulation
Corpus
luteum
follicle follicle
Follicular
phase
Luteal
Ovulation
(Day 14)
phase
(c) Fluctuation of ovarian homone levels:
Auctuating levels of ovarian hormones (estrogens
and progesterone) cause the endometrial changes
of the uterine cycle. The high estrogen levels are
also responsible for the LHVFSH surge in (a).
Estrogens
Progesterone
(d) The three phases of the uterine cycle
Menstrual: Shedding of the functional layer of
the endometrium.
Proliferative: Rebuilding of the functional layer
of the endometrium.
Secretory: Begins immediately after ovulation.
Enrichment of the blood supply and glandular
secretion of nutrients prepare the endometrium
to receive an embryo.
Blood vessels
Endometrial
glands
Menstrual
flow
Functional-
layer
Basal layer
Both the menstrual and proliferative phases occur
before ovulation, and together they correspond to the
follicular phase of the ovarian cycle. The secretory
phase corresponds in time to the luteal phase of the
ovarian cycle.
Days !
10
15
20
25
28
Menstrual
Proliferative
Secretory
phase
phase
phase
Figure 25.19 The menstrual cycle: structural and homonal changes. The time
bar near the bottom of the figure, reading Days 1 to 28, applies to all four parts
of this figure.
Plasma hormone level
Plasma hormone level
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