A.Y. is a 33-year-old woman with a history of severe asthma requiring multiple admissions and intubations, who initially presented to the emergency room with shortness of breath, wheezing, and chest pain. Presentation: History A.Y. had been in her usual state of health until this morning, when she had a sudden sensation of “tightness” in her chest accompanied by wheezing and shortness of breath. She cannot name…

Core concepts ( figs. 16.1 and 16.2 ) To function properly, the human respiratory system must: Respond to oxygen demands. Maintain a constant range of oxygen and carbon dioxide in blood. Respiration is governed by both voluntary and involuntary neural pathways. Voluntary control allows talking, eating, and drinking. Involuntary control allows respiration through wakefulness and periods of unconsciousness (i.e., sleep). Neural pathways mediating respiration are sensitive…

Introduction For successful cell respiration to occur, multiple systems must work in unison for the transport of oxygen (O 2 ) and carbon dioxide (CO 2 ): Respiratory system Hematologic system Cardiovascular system Both O 2 and CO 2 traverse these systems (blood, alveoli, and tissues) via simple diffusion. O 2 : air → alveoli → pulmonary capillaries → systemic circulation → tissue CO 2 :…

Introduction Why do we breathe? The vital importance of breathing was clear even in ancient times, when people believed that the air we breathe, or pneumo , gives rise to the spirit. Oxygen in the air enables active cellular metabolism, enabling optimal function at the cellular level and ultimately proper functioning of all of the body’s organ systems. Ultimately, the lungs bear two important responsibilities: To…

Introduction The use of oxygen for energy extraction is called aerobic respiration. In humans, gas exchange occurs in the air-filled lungs, which exposes the blood of the circulatory system to the air. Oxygen in the air of the lungs diffuses into the blood. Carbon dioxide brought from the body tissues diffuses out of the blood into the air in the lungs. For this exchange to occur…

L.B. is a 68-year-old retired accountant who has noticed worsening shortness of breath while mowing his lawn. Presentation: History L.B. was well until 6 months ago, when he noticed extreme fatigue and lightheadedness when moving from a sitting or lying to a standing position. Initially, he blamed this on lack of sleep because of shortness of breath in bed, relieved by propping his head on two…

Introduction Whether running a marathon or toting a hefty biochemistry book up a staircase, exercising muscle places demand on the body through three mechanisms: Increased oxygen and nutrient demand Increased waste products of metabolism Increased heat generation The cardiovascular, respiratory, and temperature-regulating systems of the body must adapt to meet the demands of exercising muscles. System function For a discussion of system structure, please refer to…

Introduction The heart contains specialized tissue for: (1) generating rhythmic action potentials and (2) conducting those action potentials precisely across the heart. This ensures correct timing of atrial and ventricular contraction. System structure Fig. 11.1 depicts the typical pathway of cardiac excitation. Action potentials are transmitted from sinoatrial (SA) node to atrioventricular (AV) node. Excitation proceeds through atrial muscle and specialized conducting tissues: His bundle Bundle…

Introduction As mentioned in Chapter 9 , the heart is the muscular organ that serves as the pump driving the flow of blood through the cardiovascular system. System structure Located in the mediastinum of the chest at the level of thoracic vertebrae T5–T8, the human heart is a four-chambered pump surrounded by a fibrous sac ( Fig. 10.1 ). Pericardium Most superficial tissue of the heart.…

Introduction The cardiovascular system serves as the principal transportation and distribution network of the body, allowing: Delivery of several essential substances (e.g., glucose and oxygen) to the tissues Removal of by-products of metabolism (e.g., carbon dioxide, lactate, and heat) In its simplest formulation, the system is composed of three parts: 1. Pump (the heart) 2. Series of distributing and collecting tubes (the arterial and venous systems)…

Note: This case will be presented in a slightly different format, to facilitate our discussion of the sequence of the “normal” immune response. A.P. is a 69-year-old man with hypertension (well controlled, on medications), hypercholesterolemia, and osteoarthritis of the right knee who presents with a cough, sore throat, muscle aches, and low-grade fever (100° F). On history, he remarks that he visited his grandchildren a few…

Introduction The lymphatic system plays two essential roles in the human body: 1. Absorbs fluid from interstitial space and returns fluid to intra-vascular space. a. Transports lymph filtration fluid that enters the interstitial space from the capillaries. 2. Functional connection of blood and endothelium to the immune system. a. Transport of immune cells and products. Lymphatic system structure The lymphatic system plays an essential role in…

Introduction Blood is a specialized type of connective tissue that performs several key functions required for the viability of all other organs: Major transportation route via the circulatory system. Brings oxygen and nutrients (i.e., glucose), as well as endocrine hormones. Removes carbon dioxide and waste products for disposal. Maintains body temperature. Provides defense against infection. System structure The structure of blood differs in two important aspects…

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Introduction Like skeletal muscle (see Ch. 5 ), the primary function of smooth muscle is contraction. However, although skeletal muscles often attach to bones and cross joints so that contraction produces limb movement, smooth muscle typically forms tissues within organ systems (e.g., vascular, respiratory, gastro-intestinal [GI]) to regulate the movement of liquids (blood), gases (air), and/or solids (food) within hollow tubular structures (e.g., blood vessels, bronchi,…

Introduction Muscle comes in three varieties: 1. Cardiac 2. Skeletal 3. Smooth These three types are differentiated based on: 1. Distinct control systems (neuronal, neurohormonal) 2. Anatomic locations 3. Specialized cellular structure, function, and biochemistry. The major function of skeletal muscle is its role as the effector organ in voluntary movement. It mediates transformation of central nervous system electrical activity into purposeful mechanical actions, such as…

Introduction The peripheral nervous system (PNS) is the direct extension of the central nervous system (CNS), and it is capable of consciously monitoring and reacting to primarily external stimuli. Dysfunction of this system can lead to an inability of patients to consciously interact with their environment or to receive signals that do not accurately represent their environment. It can be broken down into two subsystems: 1.…

Introduction Because of the development of new research techniques, knowledge of the brain acquired in the past 2 decades has exceeded the amount learned in all previous centuries. Numerous questions remain unanswered: “What is consciousness?” “What defines our personality?” “How can we learn better?” The central nervous system (CNS) is composed of the brain and spinal cord. Integrates information received from the body Coordinates and influences…

Introduction The nervous system actively participates in, regulates, and integrates all the other body systems. The nervous system is broadly divided into: The central nervous system (CNS) (see Ch. 3 ). Composed of brain and spinal cord. The peripheral nervous system (PNS) (see Ch. 4 ). Composed of the autonomic nervous system (ANS) and somatic nervous system. This chapter focuses on the structure and cellular physiology…

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