Introduction
today we will focus more on the heart. As we all know that living organisms require oxygen and nutrients, and a method of removing carbon dioxide and waste products. However, the circulatory system is not limited to the delivery of nutrients, gas exchange, and waste removal. Hormones, too, rely on the circulatory system to reach target organs, and the immune system depends on the transport of white blood cells and antibodies. This chapter discusses transport systems found in mammalian systems, with a focus on transport systems found in humans. watch and listen to the videos below to get more about the heart.
Task
complete the take home test and submitte it on monday next week.
instructionss: answer all the questions in your paper and submit it.
no late test will be allowed
QUESTION 1
The following diagrams show the heart during the cardiac cycle. The arrows represent the flow of blood. Study the diagrams and answer the questions that follow:
- Identify the structures labelled A and B respectively.
- Name and explain what happens in each of the phases of the cardiac cycle represented in:
- Diagram I
- Diagram II
- Diagram III
QUESTION 2
Study the accompanying diagram of the ventral view of the external structure of the heart and answer the questions that follow.
- Label parts numbered 1, 2, 7, 8.2 and 9.2
- What type of blood (oxygenated or deoxygenated) is transported by blood vessels 1, 3 and 6?
- What possible danger to human health exists if the lumen of structure 4 is obstructed with a thick layer of cholesterol?
- Discuss what happens during ventricular systole in the cardiac cycle.
QUESTION 3
Answer the following questions with a word or phrase that corresponds to the description given.
- The membrane surrounding the heart.
- The valve situated between the left atrium and left ventricle.
- The phase in the cardiac cycle when the atria contract.
- The name of the artery taking deoxygenated blood to the lungs.
- The blood circulatory system that supplies the heart muscle with oxygenated blood.
- The disorder / condition that results from a blockage in a blood vessel in the brain.
- The instrument used to measure blood pressure.
- The blood system that supplies oxygen to body cells
- The structure that separates the left and right sides of the heart.
- The ability of the heart to contract at its own inherent rhythm.
- The layer found on the inside of veins.
- The blood vessel connecting the stomach and intestine to the liver.
- Veins that have lost their elasticity and form small sacs of blood.
- The smallest blood vessels in the body.
- The pacemaker of the heart
Process
Circulatory systems in animals
Transport systems are crucial to survival. Unicellular organisms rely on simple diffusion for transport of nutrients and removal of waste. Multicellular organisms have developed more complex circulatory systems.
Open and closed circulation systems
There are two types of circulatory systems found in animals: open and closed circulatory systems.
Open circulatory systems
In an open circulatory system, blood vessels transport all fluids into a cavity. When the animal moves, the blood inside the cavity moves freely around the body in all directions. The blood bathes the organs directly, thus supplying oxygen and removing waste from the organs. Blood flows at a very slow speed due to the absence of smooth muscles, which, as you learnt previously, are responsible for contraction of blood vessels. Most invertebrates (crabs, insects, snails etc.) have an open circulatory system. Figure 7.1 shows a schematic of an open circulatory system delivering blood directly to tissues.
Closed circulatory systems
Closed circulatory systems are different to open circulatory systems because blood never leaves the blood vessels. Instead, it is transferred from one blood vessel to another continuously without entering a cavity. Blood is transported in a single direction, delivering oxygen and nutrients to cells and removing waste products. Closed circulatory systems can be further divided into single circulatory systems and double circulatory systems.
The human circulatory system involves the pulmonary and systemic circulatory systems. The pulmonary circulatory system consists of blood vessels that transport deoxygenated blood from the heart to the lungs and return oxygenated blood from the lungs to the heart. In the systemic circulatory system, blood vessels transport oxygenated blood from the heart to various organs in the body and return deoxygenated blood to the heart.
Pulmonary circulation system
In the pulmonary circulation system, deoxygenated blood leaves the heart through the right ventricle and is transported to the lungs via the pulmonary artery. The pulmonary artery is the only artery that carries deoxygenated blood. It carries blood to the capillaries where carbon dioxide diffuses out of the blood into the alveoli (lung cells) and then into the lungs, where it is exhaled. At the same time, oxygen diffuses into the alveoli, and then enters the blood and is returned to the left atrium of the heart via the pulmonary vein.
Evaluation
This how you going to be evaluated in your home test
| QUESTION | MARK | LEARNR MARK | TOTAL | ||||
| 1 | 25 | ||||||
| 2 | 30 | ||||||
| 3 | 15 |
Conclusion
In the previous sections we have discussed pulmonary and systemic circulation, and we have described the four chamber structure of the heart as well as some of the major arteries and veins that transport blood towards and away from the heart. In order to summarise all this information, study the flow diagram below which describes the passage of deoxygenated blood through one full cycle.
Credits
media / resources
TEXTBOOKS: understanding life sciences
read the information provided wisely it will guide to answer the questions in the take home test.
Teacher Page
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