Anatomy

The substance of the tongue is made up chiefly of skeletal muscle supported by connective tissue. The muscle is arranged in bundles that run in vertical, transverse and longitudinal directions. This arrangement of muscle permits intricate movements of the tongue associated with the chewing and swallowing of food, and those necessary for speech.

Superior rectal vein drains into portal system.

The bone marrow and thymus are called primary/central lymphatic organ because of their function in lymphocyte production and maturation.

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

Most common site of ectopic pregnancy is Abdominal cavity

The most abundant type of cortical neurons are the pyramidal cells. About two thirds of all cortical neurons are pyramidal. Their cell bodies are triangular, with the apex generally directed towards the surface of the cortex.

A. Prophase I: It lasts for a long time and is subdivided into the following 5 phases:

1. Leptotene : Individual chromosomes, composed of two chromatids joined at the centromere, are visible as long strands in the nucleus.

2. Zygotene: Homologous chromosomes are arranged in pairs lengthwise. This process is called synapsis or conjugation.

3. Pachytene: The two chromosomes together constitute a bivalent. A bivalent contains four chromatids in it, forming a tetrad. The two central chromatids become coiled over each other, so that they cross at a number of points (chiasmata). This is called crossing over. 

4. Diplotene: Chromosomes continue to condense and then begin to separate, revealing chiasmata.

5. Diakinesis: The homologous centromeres pull apart and the chromosomes are separated. Meanwhile the nucleolus disappears, as does the nuclear membrane, freeing the chromosomes into the cytoplasm.

Reference-BD Chaurasia’s/7th/vol-4/p-174

Stages of Mitosis:

1. Prophase: 
- The nucleolus disappears.
- The chromatins become coiled. They condense, shorten, and thicken into discrete chromosomes.
- The microtubules of the mitotic spindle appear between the two centrosomes.

2. Metaphase:
- Chromosomes migrate to the equatorial plane of the cell due to the activity of microtubules.
- Each chromosome divides longitudinally to form two chromosomes called sister chromatids.
- The chromatids attach to the microtubules of the mitotic spindle at centromere

3. Anaphase:
- The sister chromatids of each chromosome separate from each other and migrate toward the opposite poles of the cell.
- The centromeres also move away from the centre, pulling along the remainder of the chromosome.

4. Telophase:
- Nucleoli reappear in the daughter cells.
- The chromosomes become less distinct and a new nuclear envelope appears around each daughter chromosomes.
- A constriction develops at the equatorial plane of the parent cell and progresses until the cytoplasm and its organelles are divided in two.
- Formation of a new plasma membrane between the two portions of the dividing cell completes the two new cells, termed daughter cells.

Although the nail is an avascular structure, most of the nail-bed has rich vascular supply. 

Epithelium is an avascular structure, it receives nutrition from the underlying dermal capillaries. 

Cartilage receives nutrition from the perichondrium. 

Cornea receives nutrition by diffusion from the surrounding capillaries. 

*** The term dominant hemisphere refers to the side concerned with the perception and production of language/ speech. According to this concept, the left hemisphere is dominant in over 90 of people.

The term basal nucleus is applied to a collection of masses of gray matter situated within each cerebral hemisphere. They are the corpus striatum, the amygdaloid nucleus, and the claustrum.

Vessel carry blood away from the heart to the organs and tissues is called artery

1. Intramembranous ossification:
Involves direct conversion of mesenchymal tissue to bone. Bones produced by this process are called membranous (flat) bones. 
Examples: Bones of cranial vault, facial bones.

2. Endochondral (cartilaginous) ossification
Involves conversion of mesenchyme to hyaline cartilage that later gets replaced by bone.
Examples: All long bones (except clavicle), base of skull, vertebrae & ribs are formed by cartilaginous ossification. 

Uniaxial- elbow
Biaxial- wrist
Multiaxial- shoulder/hip

Mesoderm showing segmentation is - Paraxial

Reference: Junqueira’s Basic Histology; 14th Edition; Page-370

(Ref: medical examination review anatomy P:52)

Hippocampus and olfactory area.

Anteriorly, the sclera becomes continuous with the cornea at the corneoscleral junction (also called sclerocorneal junction or limbus).

Explanation: The portal vein forms when an anastomotic network around the duodenum forms one vessel. This anastomotic network is from the veins of the gut,the vitelline veins.

Appendicular artery is the branch of ileocolic artery.

Birth defect, congenital malformation, and congenital anomaly are synonymous terms used to describe structural, behavioral, functional, and metabolic
disorders present at birth.

Susceptibility to teratogens varies with the developmental stage at the time of exposure. The most sensitive period for inducing birth defects is the third to eighth weeks of gestation, the period of embryogenesis. 

Number of blastomeres in Morula – 16

Cheeks & Lateral portion of upper lip are developed from maxillary prominence.

Reference: Langman’s 13th; P-40

Most important factors which keep the Liver in position is Hepatic veins

Pons & Cerebellum are formed from metencephalon

The term basal nucleus is applied to a collection of masses of Gray matter situated within each cerebral hemisphere. They are the corpus striatum, the amygdaloid nucleus, and the claustrum.

Hepatic acini distributes nutrients and act as metabolic unit of liver.

Visceral striated muscles:
These are microscopically identical to the skeletal muscles, but they are confined to the viscera such as tongue, pharynx, peripheral part of the  diaphragm, and upper two third of esophagus.

The first meiotic division reduces the chromosome number (Reductional division), but the DNA amount is unchanged (2n)

The second meiotic division reduces the DNA amount (n), but the chromosome number is unchanged (Equatorial division)

Posttranslational modifications of proteins take place in Golgi complex

Ligamentum venosum is the true Ligament of liver.

RBC has no mitochondria

Plasma Membrane: 

Thickness: 7.5 to 10nm 

Composition: It is composed of 
a.Protein -55% 
b. Lipids: 42% 
  ✓ Phospholipids -25% 
  ✓ Cholesterol - 13% 
  ✓ Other lipids- 4% 
c. Oligosaccharides -3%

Features of epithelium:
- Epithelial tissues are composed of closely aggregated polyhedral cells adhering strongly to one another and to a thin layer of extracellular matrix (ECM).
- The forms and dimensions of epithelial cells range from high columnar to cuboidal to low squamous cells. Epithelial cell nuclei vary in shape corresponding roughly to the cell shape.
- Epithelium is an avascular structure. It receives nutrition by diffusion.
- The epithelia have got nerve supply
- Epithelial cells rest on basement membrane. 
- Epithelial cells show various types of junctions with adjacent cells and basement membrane.
- Epithelial cells isolate deeper structures from surface environment.
- Epithelial cells show surface modifications as per functional need. 
- Epithelial cells undergo mitosis and can regenerate damaged portion.
- Epithelium is derived from all three germ layers.
- Epithelial cells generally show polarity. 

Gastric ulcer occurs typically along Lesser curvature

Human placenta is - Hemochoreal

 Aspiration of any fluid from the pleural cavity is called paracentesis thoracis
 It is usually done in the eighth intercostal space in the midaxillary line
 The needle is passed through the lower part of the space to avoid injury to the principal neurovascular bundle, i e vein, artery and nerve

Epicardium is another name of Visceral pericardium

** Vitamin-D resistant rickets: X-linked dominant
** Thalassaemia & Homocystinuria: Autosomal recessive

X linked Recessive Disorders

Blood:
 Hemophilia A & B
 Glucose-6-P dehydrogenase deficiency
 Chronic granulomatous disease

Musculoskeletal:
 Duchene muscular dystrophy

Immune:
 Agammaglobinemia

Metabolic:
 Nephrogenic diabetes insipidus

Nervous:
 Fragile X syndrome

CNS development does not require influence of notochord for development.

During ventricular systole, blood should flow through the aortic valve into the aorta and not back into the left atrium. The mitral valve prevents blood going back into the left atrium.

Protein synthesis occurs in-ribosome, RER and mitochondria.