Biological Sciences
The Heart
The heart is a muscular organ that pumps blood throughout the body, supplying oxygen and nutrients to the tissues and removing waste products. It is a vital component of the circulatory system and is responsible for maintaining the body's overall function. The heart consists of four chambers and is regulated by electrical impulses to ensure proper blood flow.
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6 Key excerpts on "The Heart"
eBook - PDF- Kathleen A. Ireland(Author)
- 2018(Publication Date)
- Wiley(Publisher)
The Heart Ensures Continual, 24/7 Nutrient Delivery 269 13.1 The Heart Ensures Continual, 24/7 Nutrient Delivery LEARNING OBJECTIVES 1. Describe the structure of The Heart and blood flow through it. 2. Define extrinsic and intrinsic heart controls. 3. Explore the electrical signaling that produces contraction. 4. Describe how the tracings on an ECG reflect The Heart’s beat. On the day Dr. Seuss’s Grinch discovered the true meaning of Christ- mas, his heart grew three sizes. The Tin Man in the Wizard of Oz wanted a heart so he could have emotions. We’ve all heard The Heart described as our emotional center, but physiologically speaking, The Heart is the center of the cardiovascular (CV) system. The Heart is a pump that pushes blood through miles of blood vessels. The blood pressure generated by each heartbeat ensures that nutrients and oxygen reach every cell, directly or indirectly. To understand the importance of the CV system, look at any large city. Vehicles transport food, goods, and raw materials into the city and deliver them to residents and institutions. After the goods are consumed, waste that is left over must be recycled, burned, reused, or shipped away. Any obstruction to this flow is likely to damage the city. Imagine the disaster of a large city's garbage collection service stop- ping, even for a short period of time. Garbage would pile up, blocking traffic, impeding business, and offending millions of noses. The city would grind to a halt until trash removal resumed. Similarly, if the human body cannot move water, nutrients, and oxygen into the tis- sues and remove wastes from them, tissues will die, and the organism will die as well. In delivering oxygen and removing carbon dioxide, the cardio- vascular and respiratory systems work together. The respiratory system (Chapter 14) brings oxygen to the blood and removes carbon dioxide from it.
eBook - PDFMathematical Modelling of the Human Cardiovascular System
Data, Numerical Approximation, Clinical Applications
- Alfio Quarteroni, Luca Dede', Andrea Manzoni, Christian Vergara(Authors)
- 2019(Publication Date)
- Cambridge University Press(Publisher)
PART TWO HEART FUNCTION 4 Basic facts on quantitative cardiac physiology In this chapter we present basic facts about the anatomy and functioning of the human heart. We discuss the propagation of the electric signal, the mechanics of heart contraction and cardiac fluid dynamics; finally we provide a brief summary of heart diseases. 4.1 Basic anatomy The human heart is a hollow organ that pumps the blood into the arteries of the systemic and pulmonary circulations and collects it after its return through the veins; see e.g. (Klabunde 2012). Specifically, The Heart supplies oxygenated blood and nutrients to the body through arteries and pumps instead de-oxygenated blood to the lungs for re-oxygenation. In a healthy heart, every second, blood is pumped to almost all the 75 trillion cells of the body, which amounts to 1.5 million barrels in an average lifetime. This endeavour is made possible by the cardiac rhythm – triggered by an electric signal initiating at the sinoatrial node – and the exceptional strength and resistance of our heart. The human heart is made up of the left and right heart, each consisting of two chambers, an atrium and a ventricle. The left and right hearts are separated by the interatrial and interventricular septa, which do not allow the transfer of blood, whereas the atria and the ventricles are connected by the atrioventricular valves (tricuspid valve in the right heart, mitral valve in the left heart) that either allow or prevent the blood transfer from the atria to the ventricles depending on their configuration (open or closed, respectively): see Figure 4.1. In particular, these valves open when the atrial pressure is higher than the ventricular pressure and close as soon as the blood flow rate becomes negative, that is, when blood flow, which normally goes from the atrium to the ventricle, comes back into the atrium. In the 80 Basic facts on quantitative cardiac physiology Figure 4.1 Schematic representation of The Heart.
eBook - PDF- Bryan H. Derrickson(Author)
- 2019(Publication Date)
- Wiley(Publisher)
500 CHAPTER 14 The Cardiovascular System: The Heart The Heart and Homeostasis • The Heart contributes to homeostasis by pumping blood through blood vessels to the tissues of the body. LOOKING BACK TO MOVE AHEAD… • Equilibrium potential is the membrane potential at which the concentration gradient and electrical gradient for a particular ion are equal in magnitude but opposite in direction and there is no net movement of that ion across the plasma membrane (Section 7.3). • Acetylcholine binds to cholinergic receptors, which include muscarinic receptors and nicotinic receptors; norepinephrine and epinephrine bind to adrenergic receptors, which include alpha receptors (α 1 and α 2 ) and beta receptors (β 1 , β 2 , and β 3 ) (Section 7.5). • During muscle contraction, myosin heads of thick filaments bind to and pull on actin molecules of thin filaments, causing the thick and thin filaments to slide past one another and tension (force) to be generated (Section 11.3). • In an isotonic contraction, the tension developed by the muscle remains almost constant while the muscle changes its length; in an isometric contraction, tension is generated without the muscle changing its length (Section 11.5). 14.1 Basic Design of the Cardiovascular System 501 Introduction The cardiovascular system consists of three interrelated components: The Heart, blood ves- sels, and blood (Figure 14.1). The Heart serves as a pump that generates the pressure needed to circulate blood to the tissues of the body. To accomplish this, The Heart beats about 100,000 times every day, which adds up to 35 million beats in a year and about 3 billion beats in an aver- age lifetime. Blood vessels are tubular structures through which blood flows from The Heart to body tissues and then back to The Heart. Blood is a fluid that delivers oxygen and nutrients to cells and removes carbon dioxide and other wastes from cells. It also regulates pH and body temperature, and provides protection against disease.
eBook - PDF- Robert E. Mehler(Author)
- 2014(Publication Date)
- Wiley-Blackwell(Publisher)
7 The Heart REVIEW Would you review that overview? · The circulatory system takes to all the cells in the body what they need and takes from them what they do not need. It does this by providing a constant flow of blood very near each cell. The blood is the transport medium and flows within the confines of the circulatory system. Those confines include The Heart, which does the pumpin~ and the blood vessels-arteries, capillar-ies, and veins. The Heart and blood vessels define two The Heart is the perennial choice as the star of the circu-latory system. It provides the driving force, the pump-ing action that m.oves the blood. Simply seen, it is a hol-low muscle that, by contracting, reduces its cavity size and pushes out the blood occupying that cavity. The muscle then relaxes, refilling its hollow interior with blood. It will contract and relax again, and again, and again. This activity is automatic and spontaneous. You do not will your heart to beat. Nor can you consciously instruct it to vary its pumping performance, though when necessary The Heart can increase its output many fold. FIRST, CELLS Building an understanding of how The Heart muscle works, we begin with The Heart muscle cell, the cardiac myocyte. The cardiac myocyte has many special characteristics, but it also shares, of course, much of its physiology with the other human cells. It is interesting then to consider not only what is unique about these main circuitous routes, one to the lungs and one to the rest of the body. The components of this syst m work together with · extraordinary unity, creating physical forces that result in the proper circulation of blood to e ery cell. What is the next lecture about? The Heart --that pump (two pumps, really) which is automatic, rhythmic, responsive, and lasts a lifetime. myocytes but also what features, common to many cells, they have used or adapted to enable them to do their special work.
eBook - PDF- Gerard J. Tortora, Bryan H. Derrickson(Authors)
- 2018(Publication Date)
- Wiley(Publisher)
350 CHAPTER 15 The Cardiovascular System: Heart HANK MORGAN/Getty Images Looking Back to Move Ahead... • Functions of Blood (Section 14.1) • Membranes (Section 4.4) • Muscular Tissue (Section 4.5) • Cardiac Muscle Tissue (Section 8.7) • Action Potentials (Section 9.3) • Free Radicals (Section 2.1) • ANS Neurotransmitters (Section 11.3) In the last chapter we examined the composition and functions of blood. For blood to reach body cells and exchange materials with them, it must be constantly pumped by The Heart through the body’s blood vessels. The Heart beats about 100,000 times every day, which adds up to about 35 million beats in a year. The left side of The Heart pumps blood through an estimated 100,000 km (60,000 mi) of blood vessels. The right side of The Heart pumps blood through the lungs, enabling blood to pick up oxygen and unload carbon dioxide. Even while you are sleeping, your heart pumps 30 times its own weight each minute, which amounts to about 5 liters (5.3 qt) to the lungs and the same volume to the rest of the body. At this rate, The Heart pumps more than 14,000 liters (3600 gal) of blood in a day, or 10 million liters (2.6 million gal) in a year. You don’t spend all your time sleeping, however, and your heart pumps more vigorously when you are active. Thus, the actual blood volume The Heart pumps in a single day is much larger. This chapter explores the design of The Heart and the unique properties that permit it to pump for a lifetime without a moment of rest. 15.1 Structure and Organization of The Heart OBJECTIVES • Identify the location of The Heart and the structure and functions of the pericardium. • Describe the layers of The Heart wall and the chambers of The Heart. • Identify the major blood vessels that enter and exit The Heart. • Explain the structure and functions of the valves of The Heart.
eBook - PDFFundamentals of Critical Care
A Textbook for Nursing and Healthcare Students
- Ian Peate, Barry Hill(Authors)
- 2022(Publication Date)
- Wiley-Blackwell(Publisher)
It is then clear that cardiovascular disease is an important cause of both morbidity and mortality in critically ill adults. As such the critical care practitioner must have an awareness of important pathologies and demonstrate competence in cardiovascular monitoring and therapies. Functions of the cardiovascular system The cardiovascular system has several key functions including: • Transport: The movement of nutrients, gases and waste products around the body is crucial for cellular respira- tion and organ function. • Communication: Utilising various hormone systems to communicate throughout the body e.g. antidiuretic hormone is released in the brain (hypothalamus) stimu- lating water reabsorption in the kidney. • Thermoregulation: The manipulation of blood flow to the skin allows the regulation of temperature. • Protection: Within the blood, components of the immune and coagulation system protect against infec- tion and blood loss in the advent of injury. Anatomy of The Heart and great vessels The Heart lies within the mediastinum in the centre of the thorax with the apex projecting into the left hemithorax. It is protected by the sternum anteriorly and the vertebral column posteriorly. In essence The Heart is a pump for two Critical Care Competencies: National standards 1:3.1 Anatomy & Physiology (Critical Care Networks- National Nurse Leads (CC3N), 2015a) You must be able to demonstrate essential knowl- edge of: • Structure and function of The Heart (include chambers and valves) • Identify major/minor blood vessels • Oxygenated/deoxygenated blood flow 2:2.1 Assessment, Monitoring & Observation (Critical Care Networks-National Nurse Leads (CC3N), 2015b) 6Cs: Competence It is important you have both the knowledge and skills to effectively care for your patient.
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