Week 5 -Thorax - Grp 2 answers

Question 1

Discuss the structures air must travel through from the nose to reach the alveolar sacs of the lungs.

Answer 1

Nose
Pharynx
Larynx
Trachea
Left and right mainstem bronchi
Secondary bronchi
Tertiary bronchi
Bronchioles
Alveoli ( air sacs)
As you breathe air through your nose the air travels down your pharynx, through your larynx, and then through your trachea, which then bifurcates into the left and right mainstem(primary) bronchi. The right mainstem bronchus is shorter and wider than the left. The mainstem bronchi enter the lungs at the hilum, and divide into secondary lobar bronchi. The secondary bronchi correspond with the lobes of the lungs, with three divisions on the right and two divisions on the left. The secondary bronchi then divide into tertiary segmental bronchi which extend into each segment of the lobes. The bronchial tree then divides into smaller bronchi and then into bronchioles. Each bronchiole will divide 23 times, until it reaches the terminal end as alveoli. The alveoli are the functional units of the respiratory system. Gas exchange occurs through the walls of the alveoli between alveolar air and capillary blood.

Question 2

Discuss the structures through which lymph fluid must travel in order to leave the interstitial spaces and reach the heart.

Answer 2

The lymphatic system has small lymph vessels that carry lymph fluid into venous circulation. The thoracic duct is the main vessel that drains all of the lymph fluid.
1. It begins at the L2 level, inferior to the diaphragm and passes from the abdominal cavity to the thorax through the aortic hiatus.
2. It ascends the thorax, between the azygos vein and the descending aorta. It will then empty into the left subclavian vein at the level of the clavicle.
3. The smaller right lymphatic duct collects lymph from the right upper side of the body and is formed when the lymphatic trunks near the right clavicle merge. This duct then empties into the right subclavian vein and re enters circulation.

Question 3

Discuss the route of blood flow through the heart, the major vessels the lead to the heart, the chambers of the heart and valves, the vessels to the lungs, the vessels to the heart from the lungs, the vessel that leaves the heart.

Answer 3

Route of blood flow through the heart:
1.From the upper and lower regions of the body, deoxygenated blood from the inferior and superior vena cava flows into the right atrium and into the right ventricle. It then pumps the blood through the pulmonary valve and into the pulmonary artery. Then it travels to the lungs to be oxygenated (arteries pump blood out of the heart)

2. The left atrium gets the blood flow from the left pulmonary veins coming from the lungs. It brings oxygenated blood that goes into the left atrium, and through the bicuspid valve. Then the flow moves down the left ventricle, through the aortic semilunar valve to be sent out of the aorta and descending aorta for the rest of body to get oxygenated blood flow. (veins bring blood into the heart)

Heart valves keep blood from flowing back into previous chambers:

Atrioventricular: prevents blood flow back to the atria
Bicuspid
Tricuspid
Semilunar
Aortic: coming out of ventricle leading to aorta. Stops blood flow from reentering ventricle
Pulmonary: into pulmonary trunk out to the pulmonary arteries.Prevents blood from reentering right ventricle

Chambers of the heart:

Right atrium
Left ventricle
Left atrium
Left ventricle

Question 4

Describe how the heart muscle itself receives oxygenated blood, as well as, through what vascular structures the deoxygenated blood is returned to the heart chambers

Answer 4

Receiving Oxygenated blood
The heart muscles receives oxygenated blood through the coronary arteries. The coronary arteries branch off of the ascending aorta and leaves the left ventricular structures through the semilunar valve. The right and left sides of the heart receive the oxygenated blood. The right coronary artery descends to the right atria and right ventricular structures. The left coronary artery splits into the circumflex artery and the left anterior descending artery to supply the left atria and left ventricular structures.

Deoxygenated blood return
The cardiac veins collect blood and send it to the cardiac capillaries. The vascular structures associated with the return of deoxygenated blood to the heart are the; posterior veins, middle veins, small veins and anterior cardiac veins, which turns into the great cardiac vein. The great cardiac vein then connects to the coronary sinus where deoxygenated blood is then delivered to the right atria.

Question 5

Describe the bony structures of the thoracic cage, placement and alignment with each other.

Answer 5

The thoracic cage consists of several bony structures that form the framework of the chest cavity:

1. Sternum (Breastbone): Located in the anterior midline of the thorax, the sternum is a flat bone consisting of three parts: the manubrium, the body, and the xiphoid process. It articulates with the clavicles and the cartilages of the first seven ribs.
2. Ribs: There are 12 pairs of ribs in the human body, each attached posteriorly to the thoracic vertebrae. The upper 7 pairs are called true ribs because they articulate directly with the sternum via costal cartilages. The next 3 pairs (8th to 10th ribs) are false ribs; their cartilages join the cartilage of the 7th rib before attaching to the sternum. The last 2 pairs (11th and 12th ribs) are floating ribs, as they do not attach to the sternum anteriorly.
3. Costal Cartilages: These are hyaline cartilages that connect the anterior ends of the ribs to the sternum. They contribute to the elasticity of the thoracic cage and allow for slight movement during breathing.

The ribs are arranged in a curved fashion, with the superior ribs being shorter and more horizontally oriented, while the inferior ribs become longer and more obliquely oriented. This arrangement creates a gradually widening thoracic cage from top to bottom, providing space for the lungs and other thoracic organs. Additionally, the ribs articulate with the thoracic vertebrae posteriorly, forming the costovertebral joints, which contribute to the stability and mobility of the thoracic cage.