Anatomy

The fetal membrane that is ruptured during labor – Amnio chorionic membrane

Factors responsible for descent of testis:
1. Gubernaculum testis (main factor)
2. Differential growth of the posterior abdominal wall
3. Intraabdominal pressure
4. Intraabdominal temperature
5. Uncurling of the fetal curves
6. Arched fibres of internal oblique
7. Male sex hormones (fetal testosterone)

Peroxisomes are spherical organelles enclosed by a single membrane and named for their enzymes producing and degrading hydrogen peroxide, H₂O₂

Enzymes of peroxisomes: Catalase, D-and L-amino oxidases, urate oxidase, hydroxyacid oxidase

Functions of peroxisome:
1. Peroxisomes contain oxidative enzymes that are required for amino acid oxidation and ß-oxidation of fatty acids.
2. Inracellular hydrogen peroxide H₂O₂ is eliminated by the enzyme catalase which is present in the peroxisomes.
3. Catalase also degrades several toxic molecules and drugs, particularly in liver and kidney peroxisomes

Length of esophagus is 25cm

After fertilization, important events that take place in the first week of development-
1. Cleavage  
2. Formation of morula (16-cell stage)
3. Blastocyst formation
4. Migration of the zygote
5. Implantation

2nd week: Formation of bilaminar germ disc
The 2nd week of development is known as the week of 2's:
a) The trophoblast differentiates into 2 layers; the cytotrophoblast and syncytiotropho-blast.
b) The embryoblast forms 2 layers; the epiblast and hypoblast.
c) The extraembryonic mesoderm splits into 2 layers; the somatic and splanchnic layers.
d) 2 cavities form; the amniotic and yolk sac cavities.

3rd week: Formation of trilaminar germ disc
- Gastrulation: The process of formation of three germ layers is called gastrulation.

Explanation: Membrenous type VSD . Although the most common atrial septal defect is the secondum type ASD, the overall most common cardiac septal defect is the Membrenous type VSD.

Stomach is the most dialated part of GIT.

Functions of Golgi apparatus:
1. Post-translational modification of proteins:
Freshly synthesized proteins are transferred from RER to the Golgi apparatus. These proteins are modified by the Golgi apparatus. This is done by glycosylation, sulfation, phosphorylation, and limited proteolysis of proteins.
2. Packaging Enzymes for lysosomes and proteins for secretion
3. Storing of all materials for lysosomes, secretion, and incorporation into the plasma membrane.
4. Lysosome may be produced in the Golgi complex.
5. It is necessary for the synthesis of acrosome in the spermatozoa.

(Ref: medical examination review anatomy P:213)

Circumvallate papillae-largest & contains most taste bud

Umbilical cord contain one vein.

Coronary Sinus is the largest vein of the heart

Circumvallate papillae-largest & contains most taste bud

Reference: Langman’s 13th; P-42

Crista terminalis (an internal muscular ridge 3- to 6-mm thick), which marks the junction between the trabeculated part and smooth part of the right atrium

Most of the cells contain single nucleus except-
– RBCs and platelets do not have nuclei
– Striated muscle cells are multinucleated
– Few hepatocytes and transitional epithelial cells are binucleated

*** Normoblasts have nucleus, after this stage, they loss their nuclei to become reticulocytes, and the mature RBCs. 

Intercalated discs join the membrane of one cardiac cell with its neighbour and promote rapid conduction of depolarisation between cells.

Anosmia refers to total loss of sensation of smell, i.e., inability to recognize or detect any odor.

The fossa ovalis is the slight depression that remains when the foramen ovale closes.

Normal position of uterus is Anteverted and anteflexed

The trachea is a tube composed of 16 to 20 U-shaped hyaline cartilages and the trachealis muscle. The trachea begins just inferior to the cricoid cartilage (C6 vertebral level) and ends at the sternal angle (T4 vertebral level), where it bifurcates into the right main bronchus and the left main bronchus. At the bifurcation of the trachea, the last tracheal cartilage forms the carina, which can be observed by bronchoscopy as a raised ridge of tissue in the sagittal plane.

Explanation: The septum primum and the endocardial cushions fuse to close the foramen primum. Subsequently, perforations in the upper part of the septum primum coalesce to form septum secondum. It is this foramen that closes postnatally when the left atrial pressure equals right atrial pressure.

Middle cerebral artery-
Cortical branches supply entire lateral surface of the hemisphere except the narrow strip supplied by ant cerebral artery. the occipital pole and inferolateral surface of the hemisphere is supplied by the posterior cerebral artery.
Middle cerebral artery supplies all motor area except the leg area. central branches enter the anterior perforated substance and supply the lentiform and caudate nuclei and the internal capsule.

The fibrous skeleton is a dense framework of collagen within the heart that keeps the orifices of the atrioventricular (AV) valves and semilunar valve patent, provides an attachment site of the valve leaflets and cusps, serves as the origin and insertion sites of cardiac myocytes, and forms an electrical “barrier” between the atria and ventricles so that they contract independently.

*** The trachea has a fibroelastic wall supported by a cartilaginous skeleton formed by C shaped rings made of hyaline cartilage

Supports of rectum
• Pelvic diaphragm: formed by levator ani muscles. The puborectalis sling of this diaphragm surrounds the anorectal junction and maintain the anorectal flexure. (main support) 
• Fascia of Waldeyer: Contain Superior Rectal Vessels and lymphatics
• Lateral ligaments of Rectum: Contain Middle Rectal Vessels and lymphatics
• Rectovesical fascia of Denonvilliers
• Pelvic peritoneum
• Perineal body & its muscles

The conducting system is made up of specialized myocardium (not nervous tissue)

Its fibres are finer than other myocardial fibres and are completely cross striated

Parts:
1. Sinoatrial node (SA node)
2. Atrioventricular node (AV node)
3. Atrioventricular bundle (of His)
4. Right and left branches of AV bundle
5. Sub endocardial Purkinje fibres

Blood supply:
Whole of conducting system except left branch of AV bundle is supplied by right coronary artery. In 40% cases, left coronary artery supplies SA node. 

Phagocytosis of ECM components and debris done by macrophage

Explanation- also horizontal cells of Cajal, cells of martinotti.

♣ Terminal ductal lobular unit (TDLU) is the most active part of the breast. 
♣ Most diseases of the breast arise from the terminal ductal lobular unit (TDLU)
♣ About 50% of the ductolobular tissue is located in the upper outer quadrant and about 20% in the central region

In the distal convoluted tubules of the renal cortex, PTH stimulates Ca2+ reabsorption (and inhibits phosphate reabsorption in the proximal tubules).

Metanephros Gives rise to nephrons i.e. secretory/excretory part of the kidneys
• Bowman’s capsule
• Glomerulus
• PCT
• Loop of Henle
• DCT

Function of thymus:
1.Production, differentiation and maturation and maturation of T-lymphocytes
2.Secretion of thymopoietin by epithelioreticular cells. Thymopoietin stimulates T cell production.
3.Thymus is essential for development of immunity in early life. 
4. Another main function of the thymus is induction of central tolerance, which along with regulatory T cells prevents autoimmunity

74 days is required for spermiogenesis.

The notochord is formed by the cells of the – Mesoderm

Hepatic vein is the main support of liver.

The inferior vena cava passes through the diaphragm at the vena caval foramen. This aperture is located in the central tendon at the level of T8

Astrocyte mainly takes part in formation of blood-brain-barrier

Nucleolus:
Nucleolus is a highly basophilic spherical mass of heterochromatin in cells actively engaged in protein synthesis. The intense basophilia of nucleoli is due not to heterochromatin but to the presence of densely concentrated ribosomal RNA (rRNA).

Function of nucleolus: Ribosomal RNA (rRNA) synthesis

Superior rectal artery is the principal artery of rectum.

Capillaries have only an endothelium, with no subendothelial layer or other tunics.

Reference: Langman’s 13th; P-47

Arteriole and precapillary sphincter are Resistance vessels

Circular folds are absent in proximal part of duodenum.

Discontinuous capillaries (sinusoids) present in liver, spleen, Bone marrow.

Explanation: An ostium secondum defects is a large opening between the atria that can be caused either by excessive resorption of the septum primum or inadequate development of the septum secondum. Depending on the size of the defect, there can be shunting of blood between the atria.

Ref: BD/7th/vol-2/ page 321

Autosomal dominant disorders: 
Skeletal
1. Marfan syndrome
2. Osteogenesis imperfect
3. Achondroplasia
4. Ehlar Danlos Syndrome
Nervous
1. Huntington’s disease
2. Neurofibromatosis
3. Myotonic dystrophy
4. Tuberous sclerosis
Urinary
1. Polycystic kidney disease
Metabolic
1. Familial hypercholesterolemia
2. Acute intermittent porphyria
Gastrointestinal
1. Familial adenomatous polyposis coli
Haematopoeitic
1. Von Willebrand disease
2. Hereditary spherocytosis

Smooth endoplasmic reticulum is abundant in cells involved in lipid synthesis-
• Liver cells
• Cells of adrenal cortex
• Leydig cells of testis
• SER also appears in a specialized form, called sarcoplasmic reticulum, found in the striated muscle cells.