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By O. Hamlar. Saint John Fisher College.

CHAPTER 2 The Plasma Membrane cheap female cialis 20 mg free shipping, Membrane Transport generic female cialis 20mg visa, and the Resting Membrane Potential 25 Facilitated Diffusion Through Ion Channels buy discount female cialis 20mg line. In general buy cheap female cialis 20mg line, ion channels exist either fully 2 such as Na cheap female cialis 10 mg with amex, K , Cl , and Ca , also cross the plasma open or completely closed, and they open and close very membrane faster than would be expected based on their rapidly. The frequency with which a channel opens is vari- partition coefficients in the lipid bilayer. An ion’s electrical able, and the time the channel remains open (usually a few charge makes it difficult for the ion to move across the lipid milliseconds) is also variable. The rapid movement of ions across the membrane, port across a membrane can be controlled by changing the however, is an aspect of many cell functions. The nerve ac- frequency of a channel opening or by changing the time a tion potential, the contraction of muscle, the pacemaker channel remains open. Ion channels can be classified according to their leave the cell rapidly. This movement occurs through se- gating mechanisms, the signals that make them open or lective ion channels. There are voltage-gated channels and ligand-gated Ion channels are integral proteins spanning the width of channels. Some ion channels are always open and these are the plasma membrane and are normally composed of sev- referred to as nongated channels (see Chapter 3). Certain specific stimuli cause the Voltage-gated ion channels open when the membrane protein subunits to open a gate, creating an aqueous chan- potential changes beyond a certain threshold value. In this way, nels of this type are involved in the conduction of action ions do not need to enter the lipid bilayer to cross the mem- potentials along nerve axons and they include sodium and brane; they are always in an aqueous medium. Voltage-gated ion channels are open, the ions move rapidly from one side of channels are found in many cell types. Specific some charged amino acids located in a membrane-spanning interactions between the ions and the sides of the channel -helical segment of the channel protein are sensitive to produce an extremely rapid rate of ion movement; in fact, the transmembrane potential. Changes in the membrane ion channels permit a much faster rate of solute transport potential cause these amino acids to move and induce a 8 (about 10 ions/sec) than carrier-mediated systems. It is generally assumed open unless they first bind to a specific agonist. The opening that some kind of ionic selectivity filter must be built into of the gate is produced by a conformational change in the the structure of the channel (see Fig. The ligand can be a between the amino acid composition of the channel pro- neurotransmitter arriving from the extracellular medium. The small electrical current acetylcholine receptor channel found in the postsynaptic caused by ion movement when a channel is open can be de- neuromuscular junction (see Chapters 3 and 9) is a ligand- tected with this technique, which is so sensitive that the gated ion channel that is opened by an extracellular ligand opening and closing of a single ion channel can be ob- (acetylcholine). The current in this experiment is about 3 pA and is detected as a downward deflection in the FIGURE 2. When more than one channel opens, the current and tween the polypeptide subunits of integral pro- the downward deflection increase in direct proportion to the teins that span the plasma membrane, providing an aqueous pore number of open channels. This record shows that up to three through which ions can cross the membrane. This type of gating Out mechanism allows the channel to open or close in response to events that occur at other locations in the cell. For example, a sodium channel gated by intracellular cyclic GMP is involved 2 3 6 in the process of vision (see Chapter 4). This channel is lo- 1 4 5 cated in the rod cells of the retina and it opens in the presence of cyclic GMP. The generalized structure of one subunit of an In ion channel gated by cyclic nucleotides is shown in Figure 2. There are six membrane-spanning regions and a cyclic nucleotide-binding site is exposed to the cytosol. The func- Binding H N site COOH tional protein is a tetramer of four identical subunits. Other 2 cell membranes have potassium channels that open when the A intracellular concentration of calcium ions increases. Several known channels respond to inositol 1,4,5-trisphosphate, the IV activated part of G proteins, or ATP. The gating of the ep- ithelial chloride channel by ATP is described in the Clinical I Focus Box 2. III II B Solutes Are Moved Against Gradients by Active Transport Systems FIGURE 2. A, The secondary structure of a single The passive transport mechanisms discussed all tend to subunit has six membrane-spanning regions and a binding site for bring the cell into equilibrium with the extracellular fluid.

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The effects of sympathetic and regulation of salivary gland secretion; parasympathetic activity purchase female cialis 20 mg fast delivery, together with they are cooperative in the regulation those of hormones generic female cialis 10mg amex, help maintain of the reproductive and urinary homeostasis female cialis 20 mg online. Parasympathetic ganglia are located (c) the first cervical (C1) to the first 1 female cialis 20mg mastercard. Which of the following statements about (a) in a trunk parallel to the spinal cord generic female cialis 10mg free shipping. The neurotransmitter of preganglionic (a) preganglionic parasympathetic (d) It contains postganglionic sympathetic neurons is neurons sympathetic neurons. The preganglionic neurons of the (d) postganglionic parasympathetic (c) parasympathetic ganglia that receive sympathetic division of the autonomic neurons in sweat glands neurons from the vagus nerves. Autonomic Nervous © The McGraw−Hill Anatomy, Sixth Edition Coordination System Companies, 2001 Chapter 13 Autonomic Nervous System 453 7. Imagine yourself at the starting block of parasympathetic neurons are 1. The cooperative in parasympathetic divisions in terms of gun is about to go off in the biggest race of (a) the heart. How would you characterize (a) increased movement of the GI tract cholinergic stimulation on the his pulse? What specific role would the (b) increased mucus secretion cardiovascular and digestive systems. It would therefore result in profusely immediately after exercise than feel dry after taking this drug? Critical-Thinking Questions Nerve gas, for example, stimulates activity (d) an increase in heart rate. ANS to such an extent that it causes rapid occurs when body tissues do not receive 10. It is involved in the reflex control of the autonomic nervous system, can you predict characterized by low blood flow to the autonomic system is the type of symptoms a nerve-gas victim brain, leading to decreased levels of (a) the hypothalamus. Give evidence for the argument that the a cervical spinal cord injury be at risk of (c) the medulla oblongata. Endocrine System © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 Endocrine System 14 Introduction to the Endocrine System 455 Pituitary Gland 460 Thyroid and Parathyroid Glands 466 Pancreas 469 Adrenal Glands 471 Gonads and Other Endocrine Glands 474 Developmental Exposition: The Endocrine System 477 CLINICAL CONSIDERATIONS 480 Clinical Case Study Answer 483 Chapter Summary 484 Review Activities 485 Clinical Case Study A 38-year-old woman visited her family doctor because she had been experiencing chronic fa- tigue and weakness, especially in her legs. Upon greeting the patient, the doctor noted that al- though she was mildly obese, her face seemed unusually round. During questioning, he learned that at her recent 20-year high school reunion, nobody recognized her because her face had changed so much. Physical examination yielded, in addition to the facial findings, an unusual fat distribution that included a hump on the upper back and marked truncal obesity. Additional findings included hyperten- sion and blindness in the lateral visual fields of both eyes (bitemporal hemianopsia). Laboratory findings were remarkable for elevated blood glucose and other evidence that glucocorticoid lev- els were high. Can a correlation be drawn between the patient’s visual findings and the rest of her clini- cal picture? Does that same organ produce the hormones that directly cause the patient’s signs and symptoms? Do you suppose that a tumor elsewhere in the endocrine system could produce similar findings? Endocrine System © The McGraw−Hill Anatomy, Sixth Edition Coordination Companies, 2001 Chapter 14 Endocrine System 455 The numerous glands of the body can be classified as either of INTRODUCTION TO THE two types based on structure and function: exocrine or endocrine. ENDOCRINE SYSTEM Exocrine glands, such as sweat, salivary, and mucous glands, pro- duce secretions that are transported through ducts to their re- Hormones are regulatory chemicals secreted by the endocrine spective destinations. Each of the exocrine glands functions glands into the blood, which transports them to their target cells. The endocrine glands Feedback mechanisms in the target cells control the secretion constitute a system of their own, the endocrine system. The blood then trans- ports these hormones to specific sites called target cells, where Objective 2 Compare and contrast the nervous and they perform precise functions. The nervous system regulates body activi- Objective 3 Define mixed gland and identify the endocrine glands that are mixed.

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The neighborhood day-care center won’t third and fifth lumbar vertebrae female cialis 20 mg sale. A renal stone (calculus) discount female cialis 10mg otc, would most You’ve tried to toilet train your likely cause stagnation of urine in which 5 discount female cialis 20 mg on-line. In a male purchase 20mg female cialis free shipping, trace the path of urine from the site of filtration at the renal corpuscle to 15-month-old boy cheap female cialis 20 mg on-line, but you haven’t made portion of the urinary system? List in order all the structures through which the urine your efforts, or would it be better to wait? What functions of a real kidney does an (d) the renal pelvis artificial kidney (dialysis machine) fail to (e) the urethra types of nephrons found in a kidney. Describe the urinary bladder with regard (d) the transitional epithelium. Male Reproductive © The McGraw−Hill Anatomy, Sixth Edition Development System Companies, 2001 Male Reproductive System 20 Introduction to the Male Reproductive System 698 Perineum and Scrotum 700 Testes 702 Spermatic Ducts, Accessory Reproductive Glands, and the Urethra 707 Penis 710 Mechanisms of Erection, Emission, and Ejaculation 712 CLINICAL CONSIDERATIONS 714 Developmental Exposition: The Reproductive System 716 Clinical Case Study Answer 722 Chapter Summary 723 Review Activities 723 Clinical Case Study During a routine physical exam, a 27-year-old man mentioned to his family doctor that he and his wife had been unable to conceive a child after nearly 2 years of trying. He added that his wife had taken the initiative of having a thorough gynecological evaluation in an attempt to find out what was causing the problem. Her test findings revealed no physical conditions that could be linked to infertility. Upon palpating the patient’s testes, the doctor found nothing un- usual. When he examined the scrotal sac above the testes, however, the doctor appeared per- plexed. He informed his patient that two tubular structures, one for each testis, appeared to be absent, and that they probably had been missing since birth. During a follow-up visit, the doc- tor told the patient that examination of his ejaculate revealed azoospermia (no viable sperm). Explain how the result of the semenalysis relates to the patient’s physical exam findings. Does it seem peculiar that the patient is capable of producing an ejaculate? FIGURE: Fertility specialists have made remarkable advancements during the past decade in treating couples with fertility problems. A semenalysis reveals the relative number of sperm (sperm count), sperm vitality, and chemical nature of the fluid medium in a sample ejaculate. Male Reproductive © The McGraw−Hill Anatomy, Sixth Edition Development System Companies, 2001 698 Unit 7 Reproduction and Development (the blastocyst), pregnancy, and delivery of a baby. The more INTRODUCTION TO THE MALE complex reproductive system of the female also provides a means REPRODUCTIVE SYSTEM for nourishing the baby through the secretion of milk from the mammary glands. In addition, like in the male, another function The organs of the male and female reproductive systems are is to produce and secrete sex hormones, which maintain the fe- adapted to produce and allow the union of gametes that contain male sex organs and contribute to the female libido. A random combination of the genes during sexual In this chapter we will consider the anatomy of the male reproduction results in the propagation of individuals with genetic reproductive system; the female reproductive system is the focus differences. Objective 1 Explain why sexual reproduction is biologically advantageous. Objective 2 List the functions of the male reproductive Categories of Reproductive Structures system and compare them with those of the female. The structures of the male reproductive system can be catego- Objective 3 Distinguish between primary and secondary rized on a functional basis as follows: sex organs. The primary sex organs are called go- nads; specifically, the testes in the male. Gonads produce Unlike other body systems, the reproductive system is not essen- the gametes, or spermatozoa, and produce and secrete sex tial for the survival of the individual; it is, however, required for hormones. The secretion of male sex hormones, called an- the survival of the species. It is through reproduction that addi- drogens, at the appropriate times and in sufficient quanti- tional individuals of a species population are produced and the ties causes the development of secondary sex organs and genetic code passed from one generation to the next. Secondary sex organs are those ual reproduction, in which genes from two individuals are com- structures that are essential in caring for and transporting bined in random ways with each new generation, offers the spermatozoa. The three categories of secondary sex organs overwhelming advantage of introducing great variability into a are the sperm-transporting ducts, the accessory glands, and population. This variability of genetic constitution helps ensure the copulatory organ.

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