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Biological & Biomedical Sciences
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Biology Paper: Describe How Blood Flows Through The Heart (Reaction Paper Sample)


Biology exam

1.Describe how blood flows through the heart.
As the human heart beats, it pumps blood through the system of blood vessels known as circulatory system. These vessels are muscular and elastic to carry blood to all body parts. Blood carries oxygen from lungs and nutrients to body tissues. Moreover, it carries waste products such as carbon iv oxide away from body tissues. This generally sustain the human body tissues.
The three main blood vessels for blood transport are.
* Arteries: they began with aorta which is responsible for carrying blood away from the heart which is rich in oxygen to all body tissues. Their sizes become smaller and smaller as they branch delivering blood to organs further from the heart.
* Veins: they take blood back to the heart which as low oxygen and rich in waste products to pass from and to the heart. Generally, veins become larger as the approach the heart. The superior vena cava is the key vein that transport blood from head and arms to the heart. Similarly, the inferior vena cava transport blood from abdomen and legs into the heart.
* Capillaries: These are small, thin blood vessels that connects arteries and the veins. They have thin walls that allows oxygen, nutrient and other waste products to pass to and from our organ’s cells.
Blood flows through the body via blood vessels. The heart acts as the pump that makes it all possible.
2.What controls heart beat?
Heart beat is generally controlled by the electrical impulse in the heart which causes the heart muscles to contract and expand initiating heartbeat.
3How do arteries differ from veins?
* Arteries carry blood from heart to rest of body parts while veins carry blood back to the heart
* Almost all arteries carry oxygenated blood except pulmonary artery while almost all veins carry deoxygenated blood apart from pulmonary vein.
* Arteries have a thick elastic muscle layer while veins have thin layers i.e. heart pumps blood to arteries at high pressure thus the thick layer withstands the pressure while veins carry blood at low pressure.
* Veins have valves while arteries have none. In arteries blood flows in the right direction since its pumped from heart at high pressure. The lower blood pressure in veins requires valves to stop it from coming back.
4.what is blood pressure? what is hypertension?
The blood pressure is the pressure of the circulating blood on the walls of blood vessels.
Hypertension is also known as high blood pressure and is when the pressure of blood being pumped through arteries is higher than it should be.
5.List factors that increase the risk of cardiovascular disease.
* Smoking
* Inactivity
* Diet
* Stress
* Alcohol consumption
* Blood pressure
* Cholesterol
6.Identify 3 types of blood cells and their functions.
* Red blood cells-They carry oxygen throughout the body and provide carbon dioxide from tissues to lungs to be exhaled.
* White blood cells-The main function is to defend the body against pathogens and bacteria.
* Thrombocytes-They help the blood cells in formation of blood clots.
7.what is respiration? What is ventilation?
Ventilation is the movement of a volume of gas into and out of lungs.
Respiration is the exchange of oxygen and carbon dioxide across a membrane in lungs or cellular level.
8. How is respiration different from cellular respiration?
Cellular respiration involves the breaking down of food into usable energy (ATP) for an organism, while respiration usually is the intake of oxygen and the release carbon dioxide.
9.Outline the pathway of a breath of air from the nose to the alveoli.
Nose-air enters your body through mouth or nose where it is held in nasal cavity or oral cavity
Pharynx- this is the path way through which the both air and food travel hence important passage for digestive and respiratory tracts.
Larynx-After passing pharynx it proceeds to larynx (voice box) where it comes into contact with the glottis.
Trachea- The air travels through the trachea (wind pipe) before it leaches the lungs.
Bronchi-After air passes through the secondary bronchi it reaches tertiary bronchi which are even the small paths.
Bronchioles-They are the finest conducting pathways within the respiratory systems.
Alveoli-These are the areas within the lungs where the oxygen is transferred into the blood in exchange for carbon dioxide.
10. Explain how pulmonary gas exchange occurs.
The exchange takes place in lungs and involves respiratory processes that have contact with external environment. The process removes CO2 from blood and replenishes the blood O2 supply. Gas exchange occur down a pressure gradient via a process known as diffusion. When we breath in we inspire air consisting of O2 and CO2. These gases have pressure related to their concentration within the gas mixture. Difference in partial pressure between the gases in the alveoli and blood create a pressure gradient across respiratory membrane. The gases move from an area of high concertation to area of low concentration. Since the freshly inspired air in alveoli is high in O2 it diffuses across the membranes into blood where the concentration of O2 is low thus the blood is oxygenated and sent to tissue of the body for use. The expelled blood is high in CO2 and thus diffuses into membrane into alveoli to area of low CO2 concentration. It is the expelled via the lung. For O2 to be absorbed into the blood it binds with hemoglobin.
11. Identify three diseases of the respiratory system and state the causes of each disease.
Emphysema-caused by smoking
Malignant tumors-caused by smoking tobacco
Pulmonary edema- leakage of fluid from capillaries of the lung into alveoli.
12.What organs make up the gastrointestinal tract? What are the accessory organs of digestion?
Accessory organs of digestion are organs that helps with digestion but is not part of digestive tract. They are tongue, saliva glands, pancreas, liver and gallbladder.
Organs that make up the GI tract are: mouth, esophagus, stomach, small intestine and large intestines.
13. Describe peristalsis and its role in digestion.
Peristalsis is a series of wave-like muscle contractions that moves foods to different processing stations in the digestive tract. It begins in esophagus when a bolus of food is swallowed. The strong wave-like motions of the smooth muscle in the esophagus carry the food to the stomach where it is churned into a liquid mixture called chime. The process continues in small intestine where it mixes and shifts the chime back and forth allowing nutrients to be absorbed into the bloodstream through small intestinal walls. Peristalsis concludes in large intestine where water from the undigested food material is absorbed into the bloodstream. The waste products are excreted from the body through the rectum and anus.
14. Define mechanical and chemical digestion?
Mechanical digestion is the physical breaking of the food into smaller pieces and begins in the mouth.
Chemical digestion involves breakdown of food into simpler nutrients that can be used by the cells.
15. Describe the functions of stomach.
* The stomach can expand to store the food temporarily.
* Partial digestion of the food takes...
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