ANA 203 Victoria PDF Past Paper

# Systematic Embryology ## Musculoskeletal System (Mesodermal origin) * Forms the muscle, bone, cartilage * Bones: Formed through membranous and endochondral ossification * Muscles formation: Myoblasts fuse together to form muscle fibers. These, in turn, from muscles. * Limbs develop through Circu...

# Systematic Embryology ## Musculoskeletal System (Mesodermal origin) * Forms the muscle, bone, cartilage * Bones: Formed through membranous and endochondral ossification * Muscles formation: Myoblasts fuse together to form muscle fibers. These, in turn, from muscles. * Limbs develop through Circular Constructions (CC) and Opposite rotation (OR) of upper and lower limbs (fingers & toes). * **Interdigital Apoptosis:** Apoptosis means programmed cell death. At the stage of digital development, the interdigital webs undergo apoptosis. This death is programmed to kill the interdigital webs to separate the digits. ### Key Stages of Development 1. 3rd week: Paraxial mesoderm undergoes somitogenesis to form somites. 2. 4th week (22-28 days): Paraxial mesoderm differentiates into somites which in turn form sclerotomes and dermomyotomes. 3. Somites = dermomyotomes # Respiratory System ## Endodermal Layer * Develops during the 4th week where it forms the primitive gut tube. * Primitive gut tube develops into the GI system. * Around week 4, a small outpocketing called the respiratory diverticulum grows on the proximal part of the primitive gut tube. ## Stages of Development 1. **Lungbud** (AKA respiratory diverticulum): Formed from the foregut and develops into the entire respiratory system. 2. **Tracheoesophageal Septum:** A ridge or wall formed between the gut tube and the respiratory diverticulum, separating 2 structures: trachea & esophagus 3. **Larynx:** Develops from 4^th to 6^th pharyngeal arches. 4. **Laryngotracheal bud:** A small swelling from the lungbud forming the trachea & bronchi. # Integumentary System * Is made up of skin, nails, hair, and glands. * **Skin:** Largest organ in the body and makes up the bulk of the integumentary system. ## Functions * **Vitamin D Synthesis** * **Thermoregulation** * **Protection** from biological, physical, and chemical damage. * Skin alone cannot perform these functions and needs its appendages (hair, nails, glands). ### Layers of Skin * **Epidermis:** Outermost layer, protects from germs, UV rays, and harmful substances. * **Dermis:** Blood vessels, nerve ends, sweat glands, hair follicles, collagen and elastin for firmness and elasticity. ### Hair (ectodermal layer) * It takes about 9 weeks for hair and sebaceous glands to begin to form. * Development of hair occurs in a craniocaudal fashion (head to tail), beginning with the sebaceous area of the face, where sebaceous glands are much.  * The first sign of hair development is "hair placode". # Cardiovascular System ## Mesodermal Origin * It starts from the 3^rd week. * Includes blood vessels and the heart. ## Stages in Development 1. **Cardiac progenitor cells:** They migrate to the epiblast (outer layer of cells) and develop into cardiac myoblasts, which in turn, develop into the cardiac myoblast. 2. **Blood Islands:** Clusters of cells that develop within the mesoderm and differentiate into blood vessels and fetal red blood cells. 3. **Cardiogenic Field:** Cells come together to form a horseshoe-shaped area, surrounded by cardiac myoblasts. This region forms the heart. 4. **Heart Tube:** The cardiogenic field rotates to the left, forming a tube that connects to vascular structures and allows blood flow through it. 5. **Septa:** Partitions the heart into atria and ventricles. 6. **Valves:** Control opening and closing of atria and ventricles to prevent backflow of blood. 7. **Conduction System:** Controls the electrical activity of the heart, regulating heartbeat. 8. **Vasculature:** Develops in the heart. * **Coronary Arteries:** Supplies blood to the heart muscles. * **Aortic Artery:** Carries blood from the heart to the periphery. * **Sinus Venouses:** Group of veins returning blood to the heart. ## Clinical Symptoms 1. **Dextrocardia:** The heart is located on the right side of the chest instead of the left. 2. **Ectopic Cord:** The heart grows outside the thoracic cavity (stomach or neck). 3. **Atrial Septal Defect:** Right shunting of blood. There's a hole in the septum between the atria. Oxygenated blood is supposed to flow from the left atrium to the left ventricle, but the hole creates a detour, allowing the blood to flow into the right atrium. 4. **Ventricular Septal Defect:** A hole in the wall between ventricles, allowing oxygenated & deoxygenated blood to mix. Causes the heart to work harder. 5. **Patent Ductus Arteriosus:** Persistent opening between the aorta and pulmonary artery. **Please note:** It is not possible for me to display images. This response is limited to providing the text in the document, and I am unable to include or access images. The text, however, can be copied and pasted for use elsewhere if necessary.