Choose one of these systems and write about the following; Cardiovascular; Trace
ID: 97350 • Letter: C
Question
Choose one of these systems and write about the following;
Cardiovascular; Trace a drop of blood as it moves from the Superior vena cava through the heart, down to the right foot and back again to the heart. Describe all heart chambers, valves and major vessels (from the list you were assigned) that the drop of blood would pass through.
Respiratory; Trace a molecule of oxygen from the External nares down to the area of the lungs where it would diffuse onto a red blood cell. Describe all structures that the oxygen would pass through on its way to the lungs and once there how it arrives at the point of diffusion.
Explanation / Answer
Respiration: The process of takin in (inhaling) air (oxygen) and expelling out (exhaling) is called respiration.
A molecule of oxygen enters through nostrils (nose) and enters nasal cavity. The epithelium lining the nasal cavity has cilia and mucous. The mucous moistens the air entering and traps dust and bacteria. As air passes the nasal chambers it is warmed up.
** Nasal cavity opens into the pharynx. (throat) It is a chamber shared by the digestive and respiratory tract. The air enters through respiratory tract and enters larynx. It measures about 5cm formed by cartilages and ligaments. Larynx has vocal folds. Air rushes through the opening called glottis. This produces sound.
**Air next enters to lower respiratory tract which leads to trachea. Trachea or wind pipe is flexible tube that lies in front of the oesophagus. Trachea divides into primary bronchii this runs into the lungs of respective sides. they are made up of cartilagenous rings. The primary bronchii again divides further to secondary and tertiary bronchi. air enters through all bronchi passages. Tertiary bronchi gives rise to bronchioles. They are made up of smooth muscles in there walls. All these tracts are just conduting passages of air.
*****Alveoli: Air enters alveoli. It is made up of thin walls of smooth muscle fibres, collagen,and elastic fibres arranged diffusively. The alveoli are the structural and functional units of the respiratory system and actual sites of gaseous exchange. there are 300 million alveoli and measures 0.2mm diameter.
Lungs : they are spongy pyramidal structure. they have divisions or lobes divided by grooves called fissures. The right lung has three lobes and left lung has two. with in the lung the blood arteries branch out to form pulmonary capillary networks surrounding the alveoli. Hence each alveolus sits in the basket of capillaries.
******the membrane has air on the alveolar side and blood on the capillary side. The air or oxygen now diffuses from alveolus to blood. the blood is now called oxygenated blood.
*****During this physical exchange of gasses ther is a movement of air into and out of the lungs. called pulmonary ventillation. The oxygen is transported in the blood to tissues. By diffusion oygen is utilised by the tissue cells and carbon-di-oxide is diffused out .
The carbon-di-oxide when diffues back to blood it combines with water and forms carbonic acid. this reacts with sodium and potassium ions in blood to form respective bicarbonates. most of the CO2 is transported in the plasma in the form of sodium and potassium bicarbonates.This again reaches back to lungs and are exchanged.