Parturition & Uterine Physiology

Question 1

Describe the layers of the Uterus from superficial to deep

Answer 1

1. Perimetrium (serous epithelium)
2. Myometrium
3. *Junctional Zone
4. Endometrium
5. Uterine cavity

Question 2

What are the (3) sub-sections of the Uterus?

Answer 2

1. Fundus
2. Body
3. Cervix

Question 3

What are the sections of the cervix?

How do they differ between Nulliparous & multiparous women?

Answer 3

Supravaginal (internal) cervix:

Vaginal (External) cervix:
Nulliparous: appears circular
Multiparous: appears as a transverse Slit

Question 4

What are the nerves associated with sympathetic (adrenergic) innervation?

Associated spinal nerves?

What ganglion do they synapse at?

Answer 4

Lumbar Splanchnic Nerves: T12, L1, & L2.

Synapse at the Inferior Mesenteric Ganglion

Question 5

What are the nerves associated with Parasympathetic (Cholinergic) innervation?

Associated spinal nerves?

Answer 5

Pelvic n. S2, S3, & S4.

Question 6

Through which plexus do the sensory, sympathetic, & parasympathetic nerves pass through?

Answer 6

Hypogastric Plexus

Question 7

Parasympathetic (Cholinergic) nerves innervate what location?

Answer 7

Cervix

Question 8

Sympathetic (Adrenergic) nerves innervate what locations?

Answer 8

Fallopian tubes

Cervix

Vagina

Sparse in uterine corpus & fundus.

Question 9

The myometrium is composed of what (3) layers?

Answer 9

Tunica Muscularis;

• Stratum Supravasculare
• Stratum Vasculare
• Stratum Subvasculare

Question 10

How are the muscle fibers at the fundus are primarily oriented?

Answer 10

Mosltly Longitudinal

Question 11

How are the muscle fibers at the corpus (body) are primarily oriented?

Answer 11

Longitudinal & Oblique

Question 12

How are the muscle fibers at the Cervix are primarily oriented?

Answer 12

Circular

Question 13

In the absence of Calcium, caldesmon binds what?

Does this result in contraction or relaxation?

Answer 13

Caldesmon binds to Actin, resulting in relaxation

Question 14

Activation of PKC results in phosphorylation of what?

Does this result in contraction or relaxation?

Answer 14

PKC phosphorylates Myosin LC, resulting in Relaxation.

PKC is an antagonist of MLCK*

Question 15

Presence of Calcium acts on what?

Does this result in contraction or relaxation?

Answer 15

Calcium + Calmodulin bind to & activate MLCK;
MLCK then phosphorylates Myosin LC, resulting in contraction.

In addition, Calcium-Calmodulin binds to Caldesmon, keeping it from binding to Actin.

Calcium promotes contraction

Question 16

Calcium channel blockers have what effect on uterine smooth muscle?

Answer 16

Calcium channel blockers relax muscle by inhibiting calcium influx through voltage-operated changes (VOC’s) & Receptor-operated Channels (ROC’s).

Question 17

What signaling molecules result in relaxation of uterine smooth muscle? (3)

Answer 17

1. CRH
2. B2-Sympathomimetics
3. Prostaglandin E2

Question 18

What signaling molecules induce contraction of uterine smooth muscle? (3)

Answer 18

1. Oxytocin*
2. Thrombin
3. Prostaglandin F2a

Question 19

What changes do the changes in Estrogen & Progesterone cause in the myometrium?

Answer 19

1. Changes in the Velocity & timing of action potentials
2. Changes in membrane potentials
3. Hypertrophy & hyperplasia of the myometrial cells
4. Increased sensitivity of the myometrium
5. Alteration in the arrangement of muscle bundles
6. Development of the Sarcoplasmic Reticulum
7. Increased number of mitochondria

Question 20

During Ripening Phase 1,