Cervical incompetence
→ M/C cause of 2nd trimester loss
→ Painless, sudden dilatation of internal OS
→ Sudden rupture of membrane & expulsion of fetus.
Etiology:
Congenital
Acquired-
→ Forcible Dilatation of cervix
→ Cervix Surgery
Tag: PGI Exam
Cerebral blood supply
Normal Cerebral Blood Flow = 750 mL/min (Or) 55 mL/100g/min
Note: Flow is ½ of liver blood flow
Brain O2 consumption = 46 mL/min (20% total body O2 consumption)
→ Blood supply in Grey matter > White matter.
→ Brain HIGHLY SENSITIVE to HYPOXIA, Hippocampus is the most sensitive.
Munro Kellie Doctrine:
At any point of time, “Volume of CSF, Blood, Brain Tissue” SHOULD BE CONSTANT.
→ Significance: On alterations of any one value Compresses the other two values.
→ Ex. ↑ CSF pressure Compress Brain tissue & Blood flow.
Regulation of cerebral blood flow
Major Regulating factors – Blood pressure, PCO2 & Temperature.
The mechanism involved in each one of the factors are:
1.Blood pressure Fluctuation Bt. 65 – 140 mm Hg NO CHANGE in blood flow
AUTOREGULATION
2. PCO2
↑ PCO2 -↑ Blood Flow
3. Temperature
On ↓ Body Temp. by 1° C -↓ cerebral flow by 7% – INDUCED HYPOTHERMIA in
neurosurgical procedures – Minimizes blood loss
Indications for cerclage
1. History based indication-
→ RPL of 2nd trimester (≥2)
→ H/O PTL (Preterm Labor)
2. USG based indication
→ Length of cervix < 2.5cm + pt. giving H/O ≥ 1 second trimester abortion
3. Emergency Cerclage/ Rescue Cerclage
→ Cervix has begun dilating then do cervical cerclage. In this remember: –
- Dilation of cervix <4cm
Contraindications for cerclage
→ Cervical dilatation ≥ 4 cm
→ Ruptured membranes
→ Presence of gross anomaly of fetus
→ Vaginal bleeding Present
→ Pelvic infection +nt.
→ Placenta Previa- relative contraindication
Cells of CNS
The cells present in CNS are:
- Neurons
- Glial cells
- 1.Neurons:
- Neurons are-
- Unipolar-Seen in invertebrates
- Pseudo unipolar-Seen in dorsal root ganglion
- Bipolar-Seen in Retina & nose
- Multipolar-Seen in Spinal motor neurons
- 2.Glial cells:
- They are-
- Macroglial cells-Astrocyte, Oligodendrocyte, Schwann cell
- Microglial cells-Phagocytic cells
Causes of Intrauterine growth restriction
Maternal Causes:
• PIH
• Placental insufficiency
• Chronic renal disease
• Heart disease (NYHA 3 & 4)
• Connective tissue disorders
• Infections
• Diabetes with vasculopathy
• Diabetes with PIH
Placental Causes:
• Placental insufficiency
• Abnormal placentation
• Calcification in placenta
Fetal Causes:
• Chromosomal abnormality
• Genetic disease
• Infections
Causes of isolated spontaneous abortion
The causes for isolated spontaneous abortion in 1st & 2nd trimester include:
Chromosomal abnormalities:
1.Aneuploidy M/C
2.Trisomy – 2nd best answer
3.Monosomy X (20%)- 3rd
4.Trisomy 16 (16%)
Germ plasm defects
Fetal causes
• Weather it is first or second trimester the m/c cause is chromosomal abnormality.
The frequency of abortion during 1st trimester is 50% and during 2nd is 35%
Cardiac Muscle-Unique features
1. Gap junctions
→ SINGLE NUCLEUS CENTRALLY placed – Seen in Intercalated disc region.
→ Protein subunit – CONNEXONS – 6 subunits of “Connexin”
functions:
→ Gap junctions causes “SYNCHRONIZED CONTRACTION” / “SYNCYTIAL CONTRACTION”.
→ Entire cardiac muscle unit contracts as single unit – FUCNTIONAL SYNCYTIUM.
2. Elasticity
→ Cardiac muscle ELASTICITY – Due to TITIN (Spring type protein) “Stretch Recoil”.
→ Titin mutation – Non-elastic cardiac muscle.
→ On stretching ↑ Stretch (Non-elastic nature) Dilated Cardiomyopathy (DCM).
3.CICR
→ Calcium Induced Calcium Release
→ EXTRACELLULAR calcium induces INTRACELLULAR calcium release (Stored in sarcoplasmic reticulum).
4.Sarcoplasmic reticulum
→ Presence of WELL-DEVELOPED sarcoplasmic reticulum (SR) & SERCA pump.
→ SERCA pump & SR – Aids calcium storage.
5.PHOSPHOLAMBAN
→ INHIBITS SERCA pump & interferes with calcium storage.
Cardiac muscle v/s Skeletal muscle
| Properties | Cardiac muscle | Skeletal muscle |
| Muscle action | INVOLUNTARY –
Regulated by pacemaker (SA node) |
Voluntary
|
| Tetany | CAN’T BE tetanized | CAN BE tetanized |
| Functional unit | Sarcomere (Actin, Myosin, Tropomyosin, Troponin C etc.,) | Sarcomere (Actin, Myosin, Tropomyosin, Troponin C etc.,) |
