Physiology of Preg

8/9/2019 Physiology of Preg

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Physiology Of The Menstrual Cycle

By Zafirah Hani Bte Ramli

2008289204


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Menstrual cycle is a cycle of periodic uterine bleeding , in response to cyclic hormonalchanges that begin with the shedding of the secretory endometrium at about 14 days afterovulation.

Menstruation is the term used to indicate the periodic shedding of the stratum functionale ofthe endometrium , which becomes thickened prior to menstruation under the stimulation ofovarian steroid hormone.

A complex interaction between the hypothalmus , anterior pituaitary and the ovarieseventually leads to the process of the ovulation which is repeated with an average of 28days(range25-35 days)

The first phase: Menstruation lasts 3-5 day

Cyclic changes in the secretion of gonadotrophic hormones from the anterior pituaitary causethe ovarian changes during a monthly cycle. The ovarian cycle is accompanied by cyclicchanges in the secretion of estradiol and progesterone, which interact with thehypothalmus and pituaitary to regulate the gonadotrophin secretion. This cyclic changes inovarian hormone secretion also cause changes in the endometrium of the uterus during the

menstrual cycle


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The menstrual cycle and endometrial

changesIt is convenient to divide the cycle into phases

based on the changes that occur :

In the ovary: 1. follicular phase

2. ovulation

3. luteal phase

In the endometrium: 1. proliferative phase

2. secretory phase

3. menstrual phase


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Changes in the ovary

Follicular phase(days 1-13): At the end of menstrual cycle , estrogen levels are low. Low estrogen level stimulateproduction of FSH by the pituaitary. FSH in turns acts upon the ovary to stimulate growth of ovarian follices. Theincreasing levels of estrogen produced by the developing follicles act on the pituaitary to reduce FSH level by theprocess of negative feedback. In the majority of cycles only one follicles, the so called dominant folliclle , issufficiently large and has greater density of FSH receptors to respond to the lowers FSH level and develop to thestage of ovulation.Estrogen level continue to rise and it will reaches its highest concentrations in the blood at aboutday 12 of the cycle, 2 days before the ovulations .

Ovulation phase( day 14) : In the mid-cycle the nature of the ovarian control of pituaitary function changes.Increasing estrogen level are requires to produce a positive feedback mechanism which cause the surge in FSHand LH levels. This surge evoke the ovulation .

Luteal phase(days 15-28): LH acts to increase local production of prostaglandins and proteolytics enzymes to

allow oocyte extrussion . LH is responsible for the development of corpus luteum , which produce prostglandins


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Corticol

hypothalmic-

hypophyseal-ovarian

uterine axis


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Endometrial changes

These alterations in estrogen and progesteron level are responsible for the dramatic changes in the endometriumtroughout the ovarian cycle. At the completion of the menstrual period the endometrium is only one or twomilimeters thick. Under the influence of increasing level of estrogen this increases until the by the day 12 of thecycle the endomerium is 10-12 mm thick. This growth results from the increase in epithelial and stromal cells ofthe superficial layer of the endomnetrium . This proliferative phase is characterized by an increase in estrogenreceptor content and increase in size of the endometrial glands.

As ovulation approaches, the progestrone receptor content increases. Within two days of ovulation the effect ofovarian production of progesterone become apparent as the endometrium enters the secretory phase of thecycle. During this phase the mitotic activity in the epithelium ceases and the glands become dilated and tortuos .The blood vessels become coiled . Glycogen accumulation in the endometrium reaches a peak under thecombined influence of estrogen and progesterone. These processses prepare the endometrium for embedding ofthe embryo. If fertilization does not occur then progesterone and estrogen levels decline and menstruation occurs.


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PHYSIOLOGICAL CHANGES IN

PREGNANACY in the

-Gastrointestinal tract(GIT)

-Urinary system-Musculoskeletal system

-Central Nervous systemCNS)

JUNAINAH BT MAT JUSOP- 2008277858


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GITHigh progesterone level will cause relaxation of smoothmuscle.

Relaxation of sphincter regurgitation heartburn.

Slight reduction in gastric secretion and diminished gastric

motility slow emptying more efficient pulping of food.

Reduced motility in small intestine will provide more time forabsorption.


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Reduced motility of large intestine will increase time for water

absorption and may tends to induce constipation.

Growth of conceptus and uterus will increase appetite andthirst.

In late pregnancy ,pressure of uterus reduces capacity for large

meals.


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RENAL SYSTEMEarly pregnancy: Large uterus is compressing the bladder and cause

frequency of micturition.Mid-pregnancy: The uterus is lifted out of pelvis normal

micturition.

At term: The head of fetus descends into the pelvis frequency of

micturition.

Urinary output on a normal fluid intake tends to be slightlydiminished.

However there is an increase renal blood flow and also tubular

reabsorption of water and electrolytes.

It is estimated that extracellular water is increased by 6 to 7 litres

during pregnancy.

Glycosuria occurs commonly due to presents the tubules with a

sugar load which cannot be completed reabsorbed.


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Anatomical changes cause the exist of a degree of

hydronephrosis and hydro-ureters.

These result from loss of smooth muscle tone due to

progesterone and mechanical pressure from the uterus at the

pelvic brim.

Vesico-ureteric reflux is also increase and will lead to

infection(UTI).

It will improve in the latter part of pregnancy as the uterusgrows above the pelvic brim.


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MUSCULOSKELETAL SYSTEMProgressive lordosis,

mobility of sacroiliac, sacrococcygeal & pubic joints.

Bones & ligaments of pelvis undergo adaptation normal

relaxation.

Skin- linea nigra is prominent due to increase in ACTH.

Palmar erythema due to increase in estrogen.

Facial pigmentation-chloasma.

Pigmentation of the areola of the nipples.


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CNS

Problems with attention, concentration & memory.

Pregnancy-related memory decline : limited to 3rd trimester (

transient, quickly resolved after delivery).

Difficulty going to sleep, frequent awakenings, fewer hours of

night sleep & reduced sleep efficiency.


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THANK YOU =D


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Cardiovascular adaptation

in pregnancy

Prepared by:

Mohd Aizat B Abd Aziz

2008402162


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Why the changes occur?

Need gaseous exchange for metabolism

metabolismexcess heat

waste product Supply sufficient nutrient(growth of

fetus&uterus)

Demand Increased Blood

Supply


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How The changes Occur?

BP= CO x TPR

CO=SV x HR

BP=SV x HR x TPR

CO Blood supply


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SV(73 + 9 mL /30%)

Peripheral vascular dilatation Uterine vascular dilatation(hormonal vasodilation:PG,NO)

Reduced peripheral resistance

Lower diastolic pressure

Stimulate adrenal cortex

(secrete aldosretention fluid+

Decreased excretion Na)


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Heart Rate

70 bpm(norm)

78 bpm @ 20 weeks gestation

Peak at 85 bpm at late pregnancy

CO=SV x HRCO Blood supply


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Local Vascular Changes

CO sensitive to position of body @ >30 weeks

Exp:

Supine position pressure of uterus on pelvicvein venous return

CO (supine hypotensionsyndrome)


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Enlarged uterus exert pressure on pelvic vein

varicosities/oedema of the leg

Very prominent during daytime+uprightposture

Oedema fluid reabsorbed(when in supine

position)

venous return

renal output

Nocturnal frequency of urination


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Respiratory adaptationin pregnancy


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Mechanical Changes

Chest circumference expands 5-7 cm

Subcostal angle increases from 68 to 103

degrees

Transverse diameter increases by 2cm

Level of diaphragm elevate 4cm


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Lung volumes & capacity

Tidal volumes (35-50%)as pregnancy

progresses.

Total lung capacity is (4-5%) (d/t elevation of

diaphragm)

Large tidal volume and small residual volume

alveolar ventilation (65%)


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&


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Tidal volume

Increased

inspiration

Increased

expiration

Low maternal pCO2

Easy CO2 exchange

High arterial

O2

Improved supply

to fetus


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Changes In Reproductive Organs

Uterus

Body of uterus affected >than isthmus/cervix

Oestrogenhypertrophy/hyperplasia of muscle fibers

No of connective tissue,elastic tissue,blood

vessel,nerve increases.

Its weight can increase from 50g1000g


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Cervix

Oestrogen vascularity,changes inconnective tissuesoftens

secretion of mucusform protective plug incervical os(operculum)


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Breast

Oestrogen+progesteroneproliferation of

gland & duct

size of breast

Veins may become visible

Nipple will grow and darken.

Secretion of colostrum may begin in 1st

trimester


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Vagina and Pelvic Floor

vascularity,muscular hypertrophy,softening

connective tissue

Allow distention at birth


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Pelvic Ligament

Oestrogensoftening of the ligament

Pelvis more mobile and capacity


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HORMONAL CHANGES

DURING PREGNANCY

MUHAMAD HAZMI BIN JUAIDI

2007294732


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Hormones Produced within the

pregnant uterus

Pregnancy specific

hCG

hPL Hypothalamus related

GnRH

CRF


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Pituitary related

Prolactin

hGH

ACTH Other peptides

IGF

Calcitriol

PTH-related peptide Renin

Angiotensin 2


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Steroids

Estradiol

Progesterone


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Human chorionic gonadotrophin ( hCG

)

Secreted by the trophoblast cells within 9 days ofconception-positive urine beta hCG

Peaked at 10 weeks of gestation

Declined by 12 weeks ofgestation-placenta take over the

function over the later weeks of first trimester Composed of alpha and beta subunit, beta is pregnancy

specific, alpha unit is simmilar to a unit of FSH,LH, andTSH-can interact with the receptors

Function is to maintain the corpus luteum, so that it willcontinue to secrete estrogen and progesterone-maintainthe endometrium & prevent menstruation


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ESTROGEN

Secreted by corpus luteum in early part of pregnancythen by placenta

Concentration rises substantially from earlier part ofpregnancy-about 30 times than normal

Main actions are: On the uterus-it stimulates myometrium cells

hypertrophy-uterine enlargement for fetal growth andinhibit menstruation

Breast enlargement-ducts grow and branch

Widen the pubic symphsis- by altering the chemicalcomp. of the connective tissues


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Progesterone

Secreted by the corpus luteum and then

placenta

Main actions are :

Supress the FSH and LH to inhibit follicular

development

Prevents menstruation and thickens the

endometrium

Stimulate development of acini in the breast


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Other actions are :

1. Relaxes the smooth muscle tone leading to

discouragement of uterine contraction, GIT

symptoms like nausea and constipation

2. Reduces the vascular tone-venous

dilatation-reduced diastolic bp

3. raises temperature


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Insulin like growth factor 1 &2

Produced by fetal cells in the liver and

maternal cells in the uterus

Function is to regulate fetal growth

Fetal growth is not influenced by the growth

hormone


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Human placental Lactogen

Produced by the palcenta

Lactogenic

Antagonistic to insulin actions


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Corticosteroids

Placenta produces the corticotopin-releasing

hormone (CRH)

leads to increase in ACTH

Mother adrenal cortex will secerete cortisols

Cortisol causes increase in blood sugar

CRH also stimulate the fetal adrenal cortex torelease cortisol-stimulates maturation of lung

tissues

Th f h l b


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The onset of human labour-

placental clock theory

Initiation of labour is not well understood

Theory suggest that labour in all mammals is

initiated by the activation of fetal adrenalcortex

Upon stimulation by CRH

Outer part secrete cortisol

Inner part secrete DHEAS (

dehydroepiandosterone )


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DHEAS from fetus travel to placenta and stimulate

coversion ofprogesterone to estrogen Level of estrogen increases and stimulate the uterus to :

1. produces receptors for oxytocin

2. produces receptor for prostaglandin

3. produce gap junctions between

myometrial cells in the uterus

* uterus becomes more sensitive to pros. And oxytocin,

contractions begin and increasing in intensity


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GASTROINTESTINAL SYSTEM

High progesterone level leads to :

Relaxation of sphincter -> regurgitation -> heartburn

Diminished gastric motility result in slow emptying ->

causes nauseaReduced motility in small intestine -> more time for

absorption-> more nutrition

Reduced motility in large intestine -> more time for

water absorption -> constipationLate pregnancy -> pressure of uterus -> reduces

capacity for large meal-> frequent small snacks


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NOR AKMA BINTI SULAIMAN

2008402192


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WEIGHT INCREASE

Increase in weight around 25%

(~12.5kg)

Rate: around 0.5kg per week

Due to:

- Growth of the conceptus

- Enlargement of maternal

organs,maternal storage of fat

and protein

- Increase in maternal bloodvolume and interstitial fluid

COMPONENT AMOUNT (KG)

UTERUS

FETUS

PLACENTA

AMNIOTIC

FLUID

FAT

BLOOD

BREAST

ECF

1

~3.4

0.7

0.8

3.5

1.3

0.4

1.5-4.5

TOTAL 12.5 KG


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CARBOHYDRATE METABOLISM

Increase demand on the part

of the fetus for an easily

convertible source of energy

Future demands

lactation,increasing growth of

pregnancy,provide a more

steady source of energy

Sensitivity of insulin reduced

due to an increase in specific

antagonists to insulin- Human

Placental Lactogen (HPL)


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PROTEIN METABOLISM There is on average a 20% increase in dietary protein intake.

- Growth of the fetus,placenta,uterus,mothers breasts andother tissue.

Both chorionic gonadotrophin and the placental lactogen tend to reduce

the deamination process blood & urine urea reduced


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FAT METABOLISM Fat is the major form of stored energy during pregnancy

- Abdominal wall,back,thighs and breast (modest amount)


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Hematological changes ofnormal pregnancy


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Hematological changes of normal pregnancy

Blood volume

# The maternal blood volume increases# results from an increase in both plasma and erythrocytes.

# However, plasma volume increase in greater rate than red cell

mass.

# there are increase in red cell mass about 18% while plasmavolume increases by 40- 45%.

#Thus there is a reduction in red cell count per milliliter.

#Toward the term as the plasma volume diminishes the red cellcount increase slightly which also cause rise of haematocrit


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The factors contributing to increase of plasma volume

including:

Increase sodium retention.

Decrease in plasma osmotic pressure.

Decrease in thirst threshold.


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Why ?

Meet the demands of the enlarged uterus with it greatly

hypertrophied vascular system.

.

To safeguard the mother against the adverse effects of bloodloss associated with parturition.


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HYPERCOAGULABLE STATE: Increase in fibrinogen and factor VII and X To meet the sudden hemostatic demand during

placenta separation

INCREASE LEUKOCYTES: due to increase in neutrophil cells WCC may rise markedly during labour

DECREASE PLASMA FOLATE: Due to in renal clearance of folate in pregnancy

DECREASE TOTAL IRON STORES: Even though absorption from gut is , but there is

increasing demand for iron due to increase in bloodvolume.

l i l h


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Hematological changes

Decrease in:

o red cell count.

o hemoglobin concentration.

o haematocrit.

o Plasma folate concentration

Increase in :

o white cell count.o fibrogen concentration.

Documents

Physiology of Preg