The Mood Disorders Depressions and Bipolar Disorders

The term mood refers to a pervasive and sustained inner emotion that affects the person's perception of the world. In addition to being part of the conscious experience of the person, it can be observed by others. In healthy people, moods can be normal, elated, or depressed, and people generally feel that they have some degree of control of their moods. That sense of control is lost, however, in the mood disorders, which include depressive disorders and bipolar disorders. Along with...

Subcortical and Brainstem Nuclei

A dozen or so highly interconnected structures lie within the cerebrum beneath the cerebral cortex and in the brainstem, and they interact with the cortex to control movements. Their influence is transmitted indirectly to the motor neurons both by pathways that go to the cerebral cortex and by descending pathways that arise from some of the brainstem nuclei. It is not known to what extent, if any, these structures initiate movements, but they definitely play a prominent role in planning and...

Oxidative Phosphorylation

Fadh2 Reactive Site

Oxidative phosphorylation provides the third, and quantitatively most important, mechanism by which energy derived from fuel molecules can be transferred to ATP. The basic principle behind this pathway is simple The energy transferred to ATP is derived from the energy released when hydrogen ions combine with molecular oxygen to form water. The hydrogen comes from the NADH H and FADH2 coenzymes generated by the Krebs cycle, by the metabolism of fatty acids see below , and, to a much lesser...

Contraction and Its Control

An increase in cytosolic calcium leads to the binding of calcium by calmodulin. The calcium-calmodulin complex then binds to myosin light-chain kinase, activating the enzyme, which uses ATP to phosphorylate smooth-muscle myosin. Only phosphorylated myosin is able to bind to actin and undergo cross-bridge cycling. II. Smooth-muscle myosin has a low rate of ATP splitting, resulting in a much slower shortening velocity than is found in striated muscle. However, the tension produced per unit...

Cancer

Like the inherited genetic diseases described previously, cancer results from gene mutations. However, with a few exceptions, cancer is not an inherited genetic disease that depends on mutations in the reproductive cells. Rather, most cancers arise from mutations that can occur in any cell at anytime. As noted earlier, most mutations in a single nonreproductive cell have no effect upon the overall functioning of an organism, even if they lead to the death of that particular cell. If, however,...

Candidate Hormones

Many substances, termed candidate hormones, are suspected of being hormones in humans but are not considered classical hormones for one of two reasons Either 1 their functions have not been conclusively documented or 2 they have well-documented functions as paracrine autocrine agents, but it is not certain that they ever reach additional target cells via the blood, an essential criterion for classification as a hormone. This second category includes certain of the eicosanoids Chapter 7 and a...

Structure and Maintenance of Neurons

Neurons And Neuroglia

Neurons occur in a variety of sizes and shapes nevertheless, as shown in Figure 8-2, most of them contain four parts 1 a cell body, 2 dendrites, 3 an axon, and 4 axon terminals. As in other types of cells, a neuron's cell body contains the nucleus and ribosomes and thus has the genetic information and machinery necessary for protein synthesis. The dendrites form a series of highly branched outgrowths from the cell body. They and the cell body receive most of the inputs from other neurons, the...

Molecular Mechanisms of Contraction

Muscle Contraction Mechanism

The term contraction, as used in muscle physiology, does not necessarily mean shortening rather it refers only to the turning on of the force-generating sites the cross bridges in a muscle fiber. Following contraction, the mechanisms that initiate force generation are turned off, and tension declines, allowing relaxation of the muscle fiber. When force generation produces shortening of a skeletal-muscle fiber, the overlapping thick and thin Vander et al. Human I II. Biological Control I 11....

Receptors

Alpha Helix Protein Cell Membrane

The vast majority of homeostatic systems require cell-to-cell communication via chemical messengers. The first step in the action of any intercellular chemical messenger is the binding of the messenger to specific target-cell proteins known as receptors. In the general language of Chapter 4, a chemical messenger is a li-gand, and the receptor is a binding site. The binding of a messenger to a receptor then initiates a sequence of events in the cell leading to the cell's response to that...

If

Erythropoietic Response Blood Loss

Five simultaneous graphs showing the time course of cardiovascular effects of hemorrhage. Note that the entire decrease in arterial pressure immediately following hemorrhage is secondary to the decrease in stroke volume and, hence, cardiac output. This figure emphasizes the relativeness of the increase and decrease arrows of Figure 14-59. All variables shown are increased relative to the state immediately following the hemorrhage, but not necessarily to the state prior to the hemorrhage. only...

Skeletal Muscle Energy Metabolism

Atp Sourcers Skeletal Muscle

As we have seen, ATP performs three functions directly related to muscle-fiber contraction and relaxation see Table 11-1 . In no other cell type does the rate of ATP breakdown increase so much from one moment to the next as in a skeletal muscle fiber 20 to several hundredfold depending on the type of muscle fiber when it goes from rest to a state of contractile activity. The small supply of preformed ATP that exists at the start of contractile activity would only support a few twitches. If a...

Transport of Oxygen in Blood

Table 15-7 summarizes the oxygen content of systemic arterial blood we shall henceforth refer to systemic arterial blood simply as arterial blood . Each liter normally contains the number of oxygen molecules equivalent to 200 ml of pure gaseous oxygen at atmospheric pressure. The oxygen is present in two forms 1 dissolved in the plasma and erythrocyte water and 2 re-versibly combined with hemoglobin molecules in the erythrocytes. As predicted by Henry's law, the amount of oxygen dissolved in...

The Resting Membrane Potential

Resting Membrane Potential

All cells under resting conditions have a potential difference across their plasma membranes oriented with the inside of the cell negatively charged with respect to the outside Figure 8-7a . This potential is the resting membrane potential. a Apparatus for measuring membrane potentials. b The potential difference across a plasma membrane as measured by an intracellular microelectrode. The asterisk indicates the time the electrode entered the cell. a Apparatus for measuring membrane potentials....

Local Controls

The term local controls denotes mechanisms independent of nerves or hormones by which organs and tissues alter their own arteriolar resistances, thereby self-regulating their blood flows. It does include changes caused by autocrine paracrine agents. This self-regulation includes the phenomena of active hy-peremia, flow autoregulation, reactive hyperemia, and local response to injury. Active Hyperemia Most organs and tissues manifest an increased blood flow hyperemia when their metabolic...

Hormone Structures and Synthesis

Estradiol Synthesis And Adrenal Disease

Hormones fall into three chemical classes 1 amines, 2 peptides and proteins, and 3 steroids. The amine hormones are all derivatives of the amino acid tyrosine. They include the thyroid hormones, epinephrine and norepinephrine produced by the adrenal medulla , and dopamine produced by the hypothalamus . Thyroid Hormones The thyroid gland is located in the lower part of the neck wrapped around the front of the trachea windpipe . It is composed of many spherical structures called follicles, each...

Hypertension

Hypertension is defined as a chronically increased systemic arterial pressure. The dividing line between normal pressure and hypertension is set at approximately 140 90 mmHg. Theoretically, hypertension could result from an increase in cardiac output or in total peripheral resistance, or both. In reality, however, the major abnormality in most cases of well-established hypertension is increased total peripheral resistance caused by abnormally reduced arteriolar radius. What causes the...

Forebrain

Pituitary Gland And Olfactory Bulbs

The larger component of the forebrain see Figure 8-38 , the cerebrum, consists of the right and left cerebral hemispheres as well as certain other structures on the underside of the brain. The central core of the fore-brain is formed by the diencephalon. The cerebral hemispheres Figure 8-40 consist of the cerebral cortex, an outer shell of gray matter covering myelinated fiber tracts, which form the white matter. This in turn overlies cell clusters, which are also gray matter and are...

Ventilation and Lung Mechanics

Lung Mechanics

An inventory of steps involved in respiration Figure 15-6 is provided for orientation before beginning the detailed descriptions of each step, beginning with ventilation. 1 Ventilation Exchange of air between atmosphere and alveoli by bulk flow 2 Exchange of O2 and CO2 between alveolar air and blood in lung capillaries by diffusion 3 Transport of O2 and CO2 through pulmonary and systemic circulation by bulk flow 4 Exchange of O2 and CO2 between blood in tissue capillaries and cells in tissues...

Figure 614

Intracellular Mechanisms Hyperplasy

Cotransport and countertransport during secondary active transport driven by sodium. Sodium ions always move down their concentration gradient into a cell, and the transported solute always moves up its gradient. Both sodium and the transported solute X move in the same direction during cotransport but in opposite directions during countertransport. Vander et al. Human Physiology The Mechanism of Body Function, Eighth Edition A variety of organic molecules and a few ions are moved across...

Protein Secretion

Most proteins synthesized by a cell remain in the cell, providing structure and function for the cell's survival. Some proteins, however, are secreted into the extracellular fluid, where they act as signals to other cells or provide material for forming the extracellular matrix to which tissue cells are anchored. Since proteins are large, charged molecules that cannot diffuse through cell membranes as will be described in more Vander et al. Human Physiology The Mechanism of Body Function,...

Translation Polypeptide Synthesis

Events During Translation

After splicing, the mRNA moves through the pores in the nuclear envelope into the cytoplasm. Although the nuclear pores allow the diffusion of small molecules and ions between the nucleus and cytoplasm, they have specific energy-dependent mechanisms for the selective transport of large molecules such as proteins and RNA. In the cytoplasm, mRNA binds to a ribosome, the cell organelle that contains the enzymes and other components required for the translation of mRNA's coded message into protein....

Coronary Artery Disease and Heart Attacks

We have seen that the myocardium does not extract oxygen and nutrients from the blood within the atria and ventricles but depends upon its own blood supply via the coronary arteries. In coronary artery disease, changes in one or more of the coronary arteries causes insufficient blood flow ischemia to the heart. The result may be myocardial damage in the affected region and, if severe enough, death of that portion of the heart a myocardial infarction, or heart attack. Many patients with coronary...

Transport of Carbon Dioxide in Blood

Chemoreceptors Stimulate Mmhg

In a resting person, metabolism generates about 200 ml of carbon dioxide per minute. When arterial blood flows through tissue capillaries, this volume of carbon dioxide diffuses from the tissues into the blood Figure 15-27 . Carbon dioxide is much more soluble in water than is oxygen, and so more dissolved carbon dioxide than dissolved oxygen is carried in blood. Even so, only a relatively small amount of blood carbon dioxide is transported in this way only 10 percent of the carbon dioxide...

Hormone Metabolism and Excretion

Hormone Metabolism

A hormone's concentration in the plasma depends not only upon its rate of secretion by the endocrine gland but also upon its rate of removal from the blood, either by excretion or by metabolic transformation. The liver and the kidneys are the major organs that excrete or metabolize hormones. The liver and kidneys, however, are not the only routes for eliminating hormones. Sometimes the hormone is metabolized by the cells upon which it acts. Very importantly, in the case of peptide hormones,...

Sequence of Excitation

Heart Sequence Excitation

To reiterate, the SA node is the normal pacemaker for the entire heart. Its depolarization normally generates the current that leads to depolarization of all other cardiac muscle cells, and so its discharge rate determines the heart rate, the number of times the heart contracts per minute. The action potential initiated in the SA node spreads throughout the myocardium, passing from cell to cell by way of gap junctions. The spread Vander et al. Human Physiology The Mechanism of Body Function,...

Cell Division

Cell Cycle With Time Elapsed

Starting with a single fertilized egg, the first cell division produces 2 cells. When these daughter cells divide, they each produce 2 cells, giving a total of 4. These 4 cells produce a total of 8, and so on. Thus, starting from a single cell, 3 division cycles will produce 8 cells 23 , 10 division cycles will produce 210 1024 cells, and 20 division cycles will produce 220 1,048,576 cells. If the development of the human body involved only cell division and growth without any Vander et al....

Reflexes

Mechanism Reflex Arc

The thermoregulatory system we used as an example in the previous section, and many of the body's other homeostatic control systems, belong to the general category of stimulus-response sequences known as reflexes. Although in some reflexes we are aware of the stimulus and or the response, many reflexes regulating the internal environment occur without any conscious awareness. In the most narrow sense of the word, a reflex is a specific involuntary, unpremeditated, unlearned built-in response to...

Anticlotting Drugs

Anti Hypertension Treatment Physiology

Various drugs are used clinically to prevent or reverse clotting, and a brief description of their actions serves as a review of key clotting mechanisms. One of the most common uses of these drugs is in the prevention and treatment of myocardial infarction heart attack , which, as described in Section F, is often the result of damage to endothelial cells. Such damage not only triggers clotting but interferes with the normal anti-clotting functions of endothelial cells. For example,...

Chemical Senses

Hormone Visual Mcgraw Hill

Receptors sensitive to specific chemicals are chemore-ceptors. Some of these respond to chemical changes in the internal environment, two examples being the oxygen and hydrogen-ion receptors in certain large blood vessels Chapter 15 . Others respond to external chemical changes, and in this category are the receptors for taste and smell, which affect a person's appetite, saliva flow, gastric secretions, and avoidance of harmful substances. The specialized sense organs for taste are the 10,000...

Feedforward Regulation

Another type of regulatory process frequently used in conjunction with negative-feedback systems is feedforward. Let us give an example of feedforward and then define it. The temperature-sensitive nerve cells that trigger negative-feedback regulation of body temperature when body temperature begins to fall are located inside the body. In addition, there are temperature-sensitive nerve cells in the skin, and these cells, in effect, monitor outside temperature. When outside temperature falls, as...

Refractory Period of the Heart

Muscle Contraction Refractory Period

Ventricular muscle, unlike skeletal muscle, is incapable of any significant degree of summation of contractions, and this is a very good thing. Imagine that cardiac muscle were able to undergo a prolonged tetanic contraction. During this period, no ventricular filling could occur since filling can occur only when the ventricular muscle is relaxed, and the heart would therefore cease to function as a pump. The inability of the heart to generate tetanic contractions is the result of the long...

Balance in the Homeostasis of Chemicals

Balance Diagram For Chemical Substance

Many homeostatic systems are concerned with the balance between the addition to and removal from the body of a chemical substance. Figure 7-8 is a generalized schema of the possible pathways involved in such balance. The pool occupies a position of central importance in the balance sheet. It is the body's readily available quantity of the particular substance and is frequently identical to the amount present in the extracellular fluid. The pool receives substances from and contributes them to...

Functional Classes of Neurons

Classes Neurons Vanders

Neurons can be divided into three functional classes afferent neurons, efferent neurons, and interneurons. Afferent neurons convey information from the tissues and organs of the body into the central nervous system, efferent neurons transmit electric signals from the central nervous system out to effector cells particularly muscle or gland cells or other neurons , and interneurons connect neurons within the central nervous system Figure 8-4 . As a rough estimate, for each afferent neuron...

Cross Bridge Activation

Smooth Muscle Calcium Calmodulin

The thin filaments in smooth muscle do not have the calcium-binding protein troponin that mediates calcium-triggered cross-bridge activity in both skeletal and cardiac muscle. Instead, cross-bridge cycling in Vander et al. Human Physiology The Mechanism of Body Function, Eighth Edition Electron micrograph of portions of three smooth-muscle fibers. Higher magnification of thick filaments insert with arrows indicating cross bridges connecting to adjacent thin filaments. From A. P. Somlyo, C. E....

Figure 1114

Muscle Fiber Anatomy

Time relations between a skeletal-muscle fiber action potential and the resulting shortening and relaxation of the muscle fiber. Vander et al. Human Physiology The Mechanism of Body Function, Eighth Edition Sarcoplasmic Reticulum The sarcoplasmic reticulum in muscle is homologous to the endoplasmic reticulum found in most cells and forms a series of sleevelike structures around each myofibril Figure 11-15 , one segment surrounding the A band and another the I band. At the end of each segment...

Exchange of Gases in Alveoli and Tissues

Po2 Length Capillary

We have now completed our discussion of the lung mechanics that produce alveolar ventilation, but this is only the first step in the respiratory process. Oxygen must move across the alveolar membranes into the pulmonary capillaries, be transported by the blood to the tissues, leave the tissue capillaries and enter the extracellular fluid, and finally cross plasma membranes to gain entry into cells. Carbon dioxide must follow a similar path in reverse. In the steady state, the volume of oxygen...

Anterolateral Pain Pathway

Spinocerebellar Pathway

A stimulus that causes or is on the verge of causing tissue damage usually elicits a sensation of pain. Receptors for such stimuli are known as nociceptors. They respond to intense mechanical deformation, excessive heat, and many chemicals, including neuropeptide transmitters, bradykinin, histamine, cytokines, and prostaglandins, several of which are released by damaged cells. These substances act by combining with specific ligand-sensitive ion channels on the nociceptor plasma membrane. Vander...

Baroreceptor Reflexes

Baroreceptor Discharge

It is only logical that the reflexes that homeostatically regulate arterial pressure originate primarily with arterial receptors that respond to changes in pressure. High in the neck, each of the two major vessels Vander et al. Human Physiology The Mechanism of Body Function, Eighth Edition Locations of arterial baroreceptors. Sequence of events by which a decrease in blood volume leads to a decrease in mean arterial pressure. supplying the head, the common carotid arteries, divides into two...

Descending Pathways

Spinal Cord Crossed Pathways

The influence exerted by the various brain regions on posture and movement is via descending pathways to the motor neurons and the interneurons that affect these neurons. The pathways are of two types the corticospinal pathways, which, as their name implies, originate in the cerebral cortex and a second group we shall call the brainstem pathways, which originate in the brainstem. Fibers from both types of descending pathways end at synapses on alpha and gamma motor neurons or on interneurons...

Organization of the Respiratory System

Functions The Respiratory System

There are two lungs, the right and left, each divided into several lobes. Pulmonary is the adjective referring to lungs. The lungs consist mainly of tiny air-containing sacs called alveoli singular, alveolus , which number approximately 300 million in the adult. The alveoli are the sites of gas exchange with the blood. The airways are all the tubes through which air flows between the external environment and the alveoli. Inspiration inhalation is the movement of air from the external...

Figure 125

Withdrawal Reflex Diagram

a Passive stretch of the muscle activates the spindle stretch receptors and causes an increased rate of action potentials in the afferent nerve. b Contraction of the extrafusal fibers removes tension on the stretch receptors and lowers the rate of action potential firing. Blue arrows indicate direction of force on the muscle spindles. magnitude of the stretch and the speed with which it occurs. Although the two kinds of stretch receptors are separate entities, they will be referred to...

Control Systems Involving the Hypothalamus and Pituitary

Hypothalamus And Pituitary Gland

The pituitary gland, or hypophysis, lies in a pocket the sella turcica of the sphenoid bone at the base of the brain Figure 10-12 , just below the brain area called the hypothalamus. The pituitary is connected to the hypothalamus by the infundibulum, a stalk containing nerve fibers and small blood vessels. In adult human beings, the pituitary gland is composed of two adjacent lobes the anterior pituitary toward the front of the head and the posterior pituitary toward the back of the head each...

Autonomic Nervous System

Mesenteric Nervous System

The efferent innervation of all tissues other than skeletal muscle is by way of the autonomic nervous system. A special case occurs in the gastrointestinal tract, where autonomic neurons innervate a nerve network in the wall of the intestinal tract. This network, termed the enteric nervous system, will be described in Chapter 17. In the autonomic nervous system, parallel chains, each with two neurons, connect the central nervous system and the effector cells Figure 8-43 . This is in contrast to...

Extracellular Osmolarity and Cell Volume

Hyperosmotic Solution

We can now apply the principles learned about osmosis to cells, which meet all the criteria necessary to produce an osmotic flow of water across a membrane. Both the intracellular and extracellular fluids contain water, and cells are surrounded by a membrane that is very permeable to water but impermeable to many substances nonpenetrating solutes . About 85 percent of the extracellular solute particles are sodium and chloride ions, which can diffuse into the cell through protein channels in the...

Principles of Hormonal Control Systems

Amine Hormones Peptide Hormones Steroid Hormones Hormone Transport in the Blood Hormone Metabolism and Excretion Mechanisms of Hormone Action Hormone Receptors Events Elicited by Hormone-Receptor Binding Inputs That Control Hormone Secretion Control by Plasma Concentrations of Mineral Ions or Organic Nutrients Control by Neurons Control by Other Hormones Control Systems Involving The Hypothalamus and Pituitary Posterior Pituitary Hormones The Hypothalamus and Anterior Pituitary Hyposecretion...

Peripheral Nervous System

Nerve fibers in the peripheral nervous system transmit signals between the central nervous system and receptors and effectors in all other parts of the body. As noted earlier, the nerve fibers are grouped into bundles called nerves. The peripheral nervous system consists of 43 pairs of nerves 12 pairs of cranial nerves and 31 pairs that connect with the spinal cord as the spinal nerves. The cranial nerves and a summary of the information they transmit were listed in Table 8-8. In general, of...

Ascending Pathways

Primary Sensory Areas

The central processes of the afferent neurons enter the brain or spinal cord and synapse upon interneurons there. The central processes diverge to terminate on several, or many, interneurons Figure 9-5a and converge so that the processes of many afferent neurons terminate upon a single interneuron Figure 9-5b . The interneurons upon which the afferent neurons synapse are termed second-order neurons, and these in turn synapse with third-order neurons, and so on, until the information coded...

Types of Skeletal Muscle Fibers

Myoglobin Muscle Fibers

All skeletal-muscle fibers do not have the same mechanical and metabolic characteristics. Different types of fibers can be identified on the basis of 1 their maximal velocities of shortening fast and slow fibers and 2 the major pathway used to form ATP oxida-tive and glycolytic fibers. Fast and slow fibers contain myosin isozymes that differ in the maximal rates at which they split ATP, which in turn determine the maximal rate of cross-bridge cycling and hence the fibers' maximal shortening...

Overall Design Cardiovascular

Images Circle Pulmonary Trunk

The rapid flow of blood throughout the body is produced by pressures created by the pumping action of the heart. This type of flow is known as bulk flow because all constituents of the blood move in one direction together. The extraordinary degree of branching of blood vessels ensures that almost all cells in the body are within a few cell diameters of at least one of the smallest branches, the capillaries. Nutrients and metabolic end products move between capillary blood and the interstitial...

Motor Control Hierarchy

Spinal Cord Levels And Function

Throughout the central nervous system, the neurons involved in controlling the motor neurons to skeletal muscles can be thought of as being organized in a hierarchical fashion, each level of the hierarchy having a certain task in motor control Figure 12-1 . To begin a movement, a general intention such as pick up sweater or write signature or answer telephone is generated at the highest level of the motor control hierarchy. This highest level encompasses many regions of the brain, including...

Types of Endocrine Disorders

Defects And Hormone

Most endocrine disorders fall into one of four categories 1 too little hormone hyposecretion 2 too much hormone hypersecretion 3 reduced response of the target cells hyporesponsiveness and 4 increased response of the target cells hyperresponsive-ness . In the first two categories, the phrases too little hormone and too much hormone here mean too little or too much for any given physiological situation. For example, as we shall see, insulin secretion decreases during fasting, and this decrease...

Maintenance of Upright Posture and Balance

Postural Control Center Mass

The skeleton supporting the body is a system of long bones and a many-jointed spine that cannot stand erect against the forces of gravity without the support given by coordinated muscle activity. The muscles that maintain upright posture that is, support the body's weight against gravity are controlled by the brain and by reflex mechanisms that are wired into the neural networks of the brainstem and spinal cord. Many of the reflex pathways previously introduced for example, the stretch and...

Integration Of Cardiovascular Function Regulation Of Systemic Arterial Pressure

Peripheral Resistance Equat

In Chapter 7 we described the fundamental ingredients of all reflex control systems 1 an internal environmental variable being maintained relatively constant, 2 receptors sensitive to changes in this variable, 3 afferent pathways from the receptors, 4 an integrating center that receives and integrates the afferent inputs, 5 efferent pathways from the integrated center, and 6 effectors directed by the efferent pathways to alter their activities. The control and integration of cardiovascular...

Biogenic Amines

The biogenic amines are neurotransmitters that are synthesized from amino acids and contain an amino group R-NH2 . The most common biogenic amines are dopamine, norepinephrine, serotonin, and histamine. Epinephrine, another biogenic amine, is not a common Vander et al. Human Physiology The Mechanism of Body Function, Eighth Edition neurotransmitter in the central nervous system but is the major hormone secreted by the adrenal medulla. Norepinephrine is an important neurotransmitter in both the...

Central Control of Afferent Information

All sensory signals are subject to extensive control at the various synapses along the ascending pathways before they reach higher levels of the central nervous system. Much of the incoming information is reduced or even abolished by inhibition from collaterals from other neurons in ascending pathways lateral inhibition, discussed earlier or by pathways descending Descending pathways may control sensory information by directly inhibiting the central terminals of the afferent neuron an example...

The Scope of Human Physiology

Stated most simply and broadly, physiology is the study of how living organisms work. As applied to human beings, its scope is extremely broad. At one end of the spectrum, it includes the study of individual molecules for example, how a particular protein's shape and electrical properties allow it to function as a channel for sodium ions to move into or out of a cell. At the other end, it is concerned with complex processes that depend on the interplay of many widely separated organs in the...

Cell Organelles

Tlr And Lupid Raft

The nucleus transmits and expresses genetic information. a. Threads of chromatin, composed of DNA and protein, condense to form chromosomes when a cell divides. b. Ribosomal subunits are assembled in the nucleolus. II. Ribosomes, composed of RNA and protein, are the sites of protein synthesis. III. The endoplasmic reticulum is a network of flattened sacs and tubules in the cytoplasm. a. Granular endoplasmic reticulum has attached ribosomes and is primarily involved in the packaging of...

The Internal Environment and Homeostasis

Extracellular Fluid Plasma

An amoeba and a human liver cell both obtain their energy by breaking down certain organic nutrients. The chemical reactions involved in this intracellular process are remarkably similar in the two types of cells and involve the utilization of oxygen and the production of carbon dioxide. The amoeba picks up oxygen directly from the fluid surrounding it its external environment and eliminates carbon dioxide into the same fluid. But how can the liver cell and all other internal parts of the body...

Body Fluid Compartments

To repeat, the internal environment can be equated with the extracellular fluid. It was not stated earlier that extracellular fluid exists in two locations surrounding cells and inside blood vessels. Approximately 80 percent of the extracellular fluid surrounds all the body's cells except the blood cells. Because it lies between cells, this 80 percent of the extracellular Vander et al. Human Physiology The Mechanism of Body Function, Eighth Edition CHAPTER ONE A Framework for Human Physiology...