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Phagocytes are white blood cells (leukocytes) that engulf pathogens by phagocytosis. They include neutrophils, monocytes, and eosinophils. Monocytes enlarge into large phagocytic cells called macrophages.
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Natural killer cells (NK cells) are lymphocytes (white blood cells that mature in lymphoid tissues). NK cells kill pathogen‐infected body cells or abdominal body cells (such as tumors).
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Complement proteins are a group of about 20 proteins that “complement” defense reactions. These proteins help attract phagocytes to foreign cells and help destroy foreign cells by promoting cell lysis (breaking open the cell).
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Interferons (IFNs) are substances secreted by cells invaded by viruses that stimulate neighboring cells to produce proteins that help them defend against the viruses. Certain IFNs (such as gamma‐IFN) also amplify the activity of macrophages and NK cells.
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The inflammatory response is a series of nonspecific events that occur in response to pathogens. The response typically produces redness, swelling, heat, and pain in the target area, and often the area is disabled. When skin is damaged, for example, and bacteria, other organisms, or toxic substances enter the body, the following events occur:
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A chemical alarm is generated in the injured area. Injured cells and nearby circulating cells release chemicals that initiate defensive actions and sound an alarm to other defense mechanisms. These chemicals include histamine (mostly secreted by basophils, white blood cells found in connective tissue), kinins, prostaglandins (PGs), and complement proteins.
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Vasodilation (dilation of blood vessels), stimulated by histamine and other chemicals, increases blood supply to the damaged area. This causes redness and an increase in local temperature. The increase in temperature stimulates white blood cells and makes the environment inhospitable to pathogens.
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Vascular permeability increases in response to alarm chemicals. As a result, white blood cells, clotting factors, and body fluids move more quickly through blood vessel walls and into the injured area. The increase in body fluids that results causes local edema (swelling). Edema may produce pain if nearby nerve endings experience pressure. Pain may also occur when nerve endings are exposed to bacterial toxins, kinins, and prostaglandins. (Aspirin reduces pain by inhibiting the production of prostaglandins.)
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Phagocytes arrive at the site of injury and engulf pathogens and damaged cells. Phagocytes find the site of injury by chemotaxis, the movement of cells in response to chemical gradients (provided here by alarm chemicals).
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Complement proteins help phagocytes engulf foreign cells and stimulate basophils to release histamine.
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Fever is a total body response to infection characterized by elevated body temperature. An elevated temperature increases cellular metabolism (accelerating cellular repairs), amplifies the effect of alarm chemicals, and creates a hostile environment for bacteria. An excessively high fever may reduce the activity of enzymes necessary for cellular metabolism, thus causing the body to go further out of homeostasis.
Anatomy and Physiology
-
Anatomy and Chemistry Basics
- Quiz: What is Anatomy and Physiology?
- Atoms, Molecules, Ions, and Bonds
- Quiz: Atoms, Molecules, Ions, and Bonds
- Inorganic Compounds
- Quiz: Inorganic Compounds
- Organic Molecules
- What Is Anatomy and Physiology?
- Quiz: Organic Molecules
- Chemical Reactions in Metabolic Processes
- Quiz: Chemical Reactions in Metabolic Processes
- The Cell
- Tissues
- The Integumentary System
- Bones and Skeletal Tissues
-
The Skeletal System
- Quiz: Skull: Cranium and Facial Bones
- Hyoid Bone
- Quiz: Hyoid Bone
- Vertebral Column
- Quiz: Vertebral Column
- Organization of the Skeleton
- Quiz: Organization of the Skeleton
- Skull: Cranium and Facial Bones
- Thorax
- Quiz: Thorax
- Pectoral Girdle
- Quiz: Pectoral Girdle
- Upper Limb
- Quiz: Upper Limb
- Pelvic Girdle
- Quiz: Pelvic Girdle
- Lower Limb
- Quiz: Lower Limb
- Articulations
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Muscle Tissue
- Quiz: Types of Muscles
- Connective Tissue Associated with Muscle Tissue
- Quiz: Connective Tissue Associated with Muscle Tissue
- Structure of Skeletal Muscle
- Quiz: Structure of Skeletal Muscle
- Muscle Contraction
- Types of Muscles
- Quiz: Muscle Contraction
- Muscle Metabolism
- Structure of Cardiac and Smooth Muscle
- Quiz: Structure of Cardiac and Smooth Muscle
- The Muscular System
- Nervous Tissue
-
The Nervous System
- Nervous System Terminology
- Quiz: Nervous System Terminology
- The Brain
- Quiz: The Brain
- The Ventricles and Cerebrospinal Fluid
- Nervous System Organization
- Quiz: Nervous System Organization
- Quiz: The Ventricles and Cerebrospinal Fluid
- The Meninges
- Quiz: The Meninges
- The Blood-Brain Barrier
- Quiz: The Blood-Brain Barrier
- Cranial Nerves
- Quiz: Cranial Nerves
- The Spinal Cord
- Quiz: The Spinal Cord
- Spinal Nerves
- Quiz: Spinal Nerves
- Reflexes
- Quiz: Reflexes
- The Autonomic Nervous System
- Quiz: The Autonomic Nervous System
- The Sensory System
- The Endocrine System
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The Cardiovascular System
- Quiz: The Blood
- Blood Formation
- Quiz: Blood Formation
- Hemostasis
- Quiz: Hemostasis
- Blood Groups
- Functions of the Cardiovascular System
- Quiz: Functions of the Cardiovascular System
- The Blood
- Quiz: Blood Groups
- Circulatory Pathways
- Quiz: Circulatory Pathways
- The Heart
- Quiz: The Heart
- Cardiac Conduction
- Cardiac Muscle Contraction
- Electrocardiogram
- The Cardiac Cycle
- Cardiac Output
- Blood Vessels
- Blood Pressure
- Control of Blood Pressure
- Blood Vessels of the Body
- The Lymphatic System
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The Immune System and Other Body Defenses
- Nonspecific Barriers
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- Nonspecific Defenses
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- Specific Defense (The Immune System)
- Protecting Your Body
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- Major Histocompatibility Complex
- Quiz: Major Histocompatibility Complex
- Lymphocytes
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- Antibodies
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- Costimulation
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- Humoral and Cell-Mediated Immune Responses
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- Supplements to the Immune Response
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The Respiratory System
- Quiz: Structure of the Respiratory System
- Lungs
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- Mechanics of Breathing
- Quiz: Mechanics of Breathing
- Function of the Respiratory System
- Lung Volumes and Capacities
- Quiz: Function of the Respiratory System
- Structure of the Respiratory System
- Quiz: Lung Volumes and Capacities
- Gas Exchange
- Quiz: Gas Exchange
- Gas Transport
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- Control of Respiration
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The Digestive System
- Quiz: Structure of the Digestive Tract Wall
- Digestive Enzymes
- Quiz: Digestive Enzymes
- The Mouth
- Quiz: The Mouth
- Function of the Digestive System
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- Structure of the Digestive Tract Wall
- The Pharynx
- The Esophagus
- Quiz: The Esophagus
- Deglutition (Swallowing)
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- The Stomach
- Quiz: The Stomach
- The Small Intestine
- Quiz: The Small Intestine
- Large Intestine
- Quiz: Large Intestine
- The Pancreas
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- The Liver and Gallbladder
- Quiz: The Liver and Gallbladder
- Regulation of Digestion
- Quiz: Regulation of Digestion
- The Urinary System
- The Reproductive System
- Anatomy and Physiology Quizzes
Nonspecific Defenses
- Quiz: What is Anatomy and Physiology?
- Atoms, Molecules, Ions, and Bonds
- Quiz: Atoms, Molecules, Ions, and Bonds
- Inorganic Compounds
- Quiz: Inorganic Compounds
- Organic Molecules
- What Is Anatomy and Physiology?
- Quiz: Organic Molecules
- Chemical Reactions in Metabolic Processes
- Quiz: Chemical Reactions in Metabolic Processes
- Quiz: The Cell and Its Membrane
- Cell Junctions
- Quiz: Cell Junctions
- Movement of Substances
- Quiz: Movement of Substances
- Cell Division
- The Cell and Its Membrane
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- Epithelial Tissue
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- Connective Tissue
- Quiz: Connective Tissue
- Nervous Tissue
- Introduction to Tissues
- Quiz: Nervous Tissue
- Muscle Tissue
- Quiz: Muscle Tissue
- Quiz: The Skin and Its Functions
- The Epidermis
- Quiz: The Epidermis
- The Dermis
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- The Hypodermis
- The Skin and Its Functions
- Quiz: The Hypodermis
- Accessory Organs of the Skin
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- Quiz: Types of Bones
- Bone Structure
- Quiz: Bone Structure
- Bone Development
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- Bone Growth
- Functions of Bones
- Quiz: Functions of Bones
- Types of Bones
- Quiz: Bone Growth
- Bone Homeostasis
- Quiz: Bone Homeostasis
- Surface Features of Bones
- Quiz: Surface Features of Bones
- Quiz: Skull: Cranium and Facial Bones
- Hyoid Bone
- Quiz: Hyoid Bone
- Vertebral Column
- Quiz: Vertebral Column
- Organization of the Skeleton
- Quiz: Organization of the Skeleton
- Skull: Cranium and Facial Bones
- Thorax
- Quiz: Thorax
- Pectoral Girdle
- Quiz: Pectoral Girdle
- Upper Limb
- Quiz: Upper Limb
- Pelvic Girdle
- Quiz: Pelvic Girdle
- Lower Limb
- Quiz: Lower Limb
- Classifying Joints
- Quiz: Classifying Joints
- Quiz: Types of Muscles
- Connective Tissue Associated with Muscle Tissue
- Quiz: Connective Tissue Associated with Muscle Tissue
- Structure of Skeletal Muscle
- Quiz: Structure of Skeletal Muscle
- Muscle Contraction
- Types of Muscles
- Quiz: Muscle Contraction
- Muscle Metabolism
- Structure of Cardiac and Smooth Muscle
- Quiz: Structure of Cardiac and Smooth Muscle
- Quiz: Skeletal Muscle Actions
- Names of Skeletal Muscles
- Quiz: Names of Skeletal Muscles
- Muscle Size and Arrangement of Muscle Fascicles
- Quiz: Muscle Size and Arrangement of Muscle Fascicles
- Major Skeletal Muscles
- Skeletal Muscle Actions
- Quiz: Major Skeletal Muscles
- Neuroglia
- Quiz: Neuroglia
- Myelination
- Quiz: Myelination
- Transmission of Nerve Impulses
- Neurons
- Quiz: Neurons
- Quiz: Transmission of Nerve Impulses
- The Synapse
- Quiz: The Synapse
- Nervous System Terminology
- Quiz: Nervous System Terminology
- The Brain
- Quiz: The Brain
- The Ventricles and Cerebrospinal Fluid
- Nervous System Organization
- Quiz: Nervous System Organization
- Quiz: The Ventricles and Cerebrospinal Fluid
- The Meninges
- Quiz: The Meninges
- The Blood-Brain Barrier
- Quiz: The Blood-Brain Barrier
- Cranial Nerves
- Quiz: Cranial Nerves
- The Spinal Cord
- Quiz: The Spinal Cord
- Spinal Nerves
- Quiz: Spinal Nerves
- Reflexes
- Quiz: Reflexes
- The Autonomic Nervous System
- Quiz: The Autonomic Nervous System
- Quiz: Sensory Receptors
- The Somatic Senses
- Quiz: The Somatic Senses
- Vision
- Quiz: Vision
- Hearing
- Sensory Receptors
- Quiz: Hearing
- Equilibrium
- Quiz: Equilibrium
- Smell
- Quiz: Smell
- Taste
- Quiz: Taste
- Quiz: The Hypothalamus and Pituitary Glands
- Endocrine Organs and Tissues
- Quiz: Endocrine Organs and Tissues
- Antagonistic Hormones
- Quiz: Antagonistic Hormones
- Hormones
- Quiz: Hormones
- The Hypothalamus and Pituitary Glands
- Quiz: The Blood
- Blood Formation
- Quiz: Blood Formation
- Hemostasis
- Quiz: Hemostasis
- Blood Groups
- Functions of the Cardiovascular System
- Quiz: Functions of the Cardiovascular System
- The Blood
- Quiz: Blood Groups
- Circulatory Pathways
- Quiz: Circulatory Pathways
- The Heart
- Quiz: The Heart
- Cardiac Conduction
- Cardiac Muscle Contraction
- Electrocardiogram
- The Cardiac Cycle
- Cardiac Output
- Blood Vessels
- Blood Pressure
- Control of Blood Pressure
- Blood Vessels of the Body
- Lymphatic Vessels
- Quiz: Lymphatic Vessels
- Lymphoid Cells
- Quiz: Lymphoid Cells
- Lymphatic Tissues and Organs
- Lymphatic System Components
- Quiz: Lymphatic System Components
- Quiz: Lymphatic Tissues and Organs
- Nonspecific Barriers
- Quiz: Nonspecific Barriers
- Nonspecific Defenses
- Quiz: Nonspecific Defenses
- Specific Defense (The Immune System)
- Protecting Your Body
- Quiz: Specific Defense (The Immune System)
- Major Histocompatibility Complex
- Quiz: Major Histocompatibility Complex
- Lymphocytes
- Quiz: Lymphocytes
- Antibodies
- Quiz: Antibodies
- Costimulation
- Quiz: Costimulation
- Humoral and Cell-Mediated Immune Responses
- Quiz: Humoral and Cell-Mediated Immune Responses
- Supplements to the Immune Response
- Quiz: Supplements to the Immune Response
- Quiz: Structure of the Respiratory System
- Lungs
- Quiz: Lungs
- Mechanics of Breathing
- Quiz: Mechanics of Breathing
- Function of the Respiratory System
- Lung Volumes and Capacities
- Quiz: Function of the Respiratory System
- Structure of the Respiratory System
- Quiz: Lung Volumes and Capacities
- Gas Exchange
- Quiz: Gas Exchange
- Gas Transport
- Quiz: Gas Transport
- Control of Respiration
- Quiz: Control of Respiration
- Quiz: Structure of the Digestive Tract Wall
- Digestive Enzymes
- Quiz: Digestive Enzymes
- The Mouth
- Quiz: The Mouth
- Function of the Digestive System
- Quiz: Function of the Digestive System
- Structure of the Digestive Tract Wall
- The Pharynx
- The Esophagus
- Quiz: The Esophagus
- Deglutition (Swallowing)
- Quiz: Deglutition (Swallowing)
- The Stomach
- Quiz: The Stomach
- The Small Intestine
- Quiz: The Small Intestine
- Large Intestine
- Quiz: Large Intestine
- The Pancreas
- Quiz: The Pancreas
- The Liver and Gallbladder
- Quiz: The Liver and Gallbladder
- Regulation of Digestion
- Quiz: Regulation of Digestion
- Quiz: Regulation of Urine Concentration
- Ureters
- Quiz: Ureters
- Urinary Bladder
- Quiz: Urinary Bladder
- Anatomy of the Kidneys
- Quiz: Anatomy of the Kidneys
- Regulation of Urine Concentration
- Urethra
- Quiz: Urethra
- Quiz: What Is Reproduction?
- The Male Reproductive System
- Quiz: The Male Reproductive System
- The Female Reproduction System
- Quiz: The Female Reproduction System
- What Is Reproduction?
- Online Quizzes for CliffsNotes Anatomy and Physiology QuickReview, 2nd Edition
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