CH. 4 Essential Physiology Flashcards
Essential Physiology
ESSENTIAL PHYSIOLOGY:
- Remember that all that psychology comes from our biology.
- A premise of health psychology is that our minds (e.g., how we think), our personalities, and our behaviors influence our bodies and our biology.
Biological Development
BIOLOGY DEVELOPMENT:
PARENTAL PERIOD – The infant is born with predispositions and a genetic inheritance that shape many future developments.
PRENATAL PERIOD – The time before a baby is born.
- The less time that the baby has in the womb, or in utero, the less time it will have to grow and develop normally.
GESTATION – Time in the womb.
- Is one of the most important health psychological outcome variables used to study pregnancy.
PRETERM BIRTHS – Those where delivery occurs before 37 weeks of gestation, are the most direct causes of Low-Birth-Weight (LBW) babies.
LOW-BIRTH-WEIGHT (LBW) – Babies who have a higher risk for developmental and mental complications over the first few years of life.
- The biological development of the fetus can be seriously influenced by the psychological state of the mother—her moods, her feelings, and her thoughts (the psycho part)—as well as the networks she has and the social situation in which she is living (the social part).
- In fact, the quality of the social environment the mother lives in may prove to be one of the main factors in the influence psychosocial aspects have on healthy biological functioning.
- Only hearing develops before birth.
- The Mozart effect the finding that listening to the first movement allegro con spirito of Mozart’s Sonata for Two Pianos in D major (K 448) can improve performance in certain areas.
- aAmajor meta-analysis shows there is little evidence for the performance-enhancing effect of listening to Mozart.
- Black and Hispanic pregnant women are more likely to use both tobacco and marijuana during pregnancy than White women.
- Stress is particularly dangerous to the prenatal infant; and the more stress a mother experiences, the more she risks delivery of a preterm or LBW baby.
Two other aspects of pregnancy have strong psychological components:
- Miscarriage and Labor/Delivery.
MISCARRIAGE – (Medically referred to as a spontaneous abortion) occurs when the zygote, embryo, or fetus detaches from the uterus before it is ready to survive on its own.
- Miscarriages occur often. Between 15% and 20% of pregnancies end in miscarriage.
- Smoking, is one of the big culprits.
- Miscarriage can be a traumatizing experience, the way they process their feelings and cope with this event can have major implications for their mental and physical health.
- Childbirth is a stressful event, especially because it involves risk to both the mother’s and the infant’s lives.
- Social support will prove important over the life span in general.
- Close family relationships, especially during childhood, can reduce the extent of health issues across an individual’s life span.
Infancy and Early Childhood
INFANCY AND EARLY CHILDHOOD:
- The nervous system develops the most rapidly in the early months.
- How parents interact with their babies is a key factor in infant development.
- Greater physical contact between the caregiver and child has always been associated with more successful social and physical development.
- Touch has other important influences, and plays a role in stress and coping,
- Middle childhood (age 7 to adolescence) is the stage during which children tend to be the healthiest and experience significant changes in cognitive development.
Adolescence
ADOLESCENCE:
- Adolescence (ages 12 to 17) can be perhaps one of the most turbulent periods in an individual’s life. A flurry of biological activity morphs the child into a young adult and sometimes the grown-up exterior surges ahead of the still underdeveloped interior or cognitive development. This mismatch between biological and psychological factors often has dire health consequences.
PUBERTY – Genetic timing mechanism activates the pituitary gland and an increasing level of growth hormone is produced in the body.
- Boys with higher levels of testosterone are more likely to make risky decisions.
- The age at which puberty occurs has been shifting forward in time, demonstrating the possible interaction between our biology and our psychology and society (Lee & Styne, 2013). For example, at the beginning of the 20th century the average age for the onset of menstruation was 15 or 16. Less than a century later, the average age was just older than 12.
- Why is this the case? The best guesses are increases in stress and higher levels of environmental toxins in contemporary society, but there is no answer yet.
- Environmental factors combine to make this physiological milestone a great equalizer of ethnic differences. When girls of Jewish, African, Italian, and Japanese descent are raised under the same living conditions, they all begin to menstruate at the same early age.
- Furthermore, after years of immigration, regardless of ethnicity, girls menstruate earlier in North America than they would have if they had stayed in their countries of origin.
- Both boys and girls experience a growth spurt, although this tends to happen for girls almost 2 years before it happens for boys.
Adult and Aging
ADULT AND AGING – Ages 18 to 21 are often referred to as the young adult years.
- During this period, our health behaviors are perhaps most important in determining how pain free we live our lives and how long we will live.
- Some changes do happen. The hair tends to thin and turn gray, and many men experience receding hairlines. The storage of body fat also increases and the distribution of fat changes.
- For example, our bodies store more fat on our waists, causing an increased waistto-hip ratio (WHR). Higher WHRs are warning signs for coronary heart disease and a signal of excessive wear and tear on the body.
- Constant physical activity is necessary to compensate during these years.
MENOPAUSE – The ending of the menstrual period, typically occurs in the early 50s.
- Psychology can play a role in this as well. Reactions to menopause vary greatly, depending on the expectations that women have.
- Psychology can play a role in this as well. Reactions to menopause vary greatly, depending on the expectations that women have.
- Being Mentally and Physically Active Has Few Age Limits. Although there are some natural physiological changes as we age, the greater cause of loss of muscle tone is not using them enough. TJB– Like I always say.
- The bigger issue on the table is whether women should start taking hormone pills to replace the natural cycle. Hormone replacement therapy was a common practice for many years. Then, in 2002, the intervention arm of the Women’s Health Initiative study testing the effects of hormone replacement was halted because women receiving the drug were found to have a higher risk for certain cancers.
- Some evidence suggests that some forms of hormone replacement may be safe.
- Although we often stereotype older adults as being weak and forgetful, the natural breakdown of muscles and the loss of memory do not start until much later in life.
- In a longitudinal study begun in 1956, Schaie (1993) demonstrated that the majority of participants showed no significant decline in most mental abilities until the age of 81. The common saying, “Use it or lose it,” is very pertinent. Maintaining a constant routine of physical activity can prolong good health and activity and ensure that an aging adult can continue to perform comfortably the activities of daily living into their 70s and 80s. Similarly, older adults who have new experiences to occupy their minds, such as solving crossword puzzles, experience less memory loss over time. Important!
The Nervous System
THE NERVOUS SYSTEM – Understanding the physiological bases of stress provides us with a better understanding of how psychology can make a difference.
- The nervous system is the most critical physiological player.
- The nervous system can be divided into two main parts:
- CENTRAL NERVOUS SYSTEM – (Consisting of the brain and spinal cord)
- PERIPHERAL NERVOUS SYSTEM – (Consisting of all the nervous tissue and cells outside the brain and spinal cord).
Central Nervous System
CENTRAL NERVOUS SYSTEM – The primary function of the central nervous system (CNS) is to process and coordinate information that it receives from the peripheral nervous system.
- The CNS is the command center of the body with the brain as the main coordinator.
The Vertebrate Brain Can Be Divided Into Three Main Parts:
HINDBRAIN – Is located at the back of the brain and consists of the medulla, pons, and cerebellum.
MEDULLA – Controls life-support functions (e.g., breathing)
PONS – Relays information from the spinal cord to the higher brain areas.
CEREBELLUM – Controls motor coordination and movement in response to sensory stimuli.
MIDBRAIN – Consists of structures that process visual information (superior colliculus) and auditory information (inferior colliculus) and those that play a key role in attention, pain control, and emotions (tegmentum, periaqueductal gray, and substantia nigra).
RETICULAR FORMATION – Plays a key role in the stress response, handling emergency responses. It is a group of neurons that takes up a large portion of the midbrain but runs from the hindbrain to the forebrain.
FOREBRAIN – The part of the brain that you most likely associate with the word brain, that bean-shaped structure with grooves and fissures.
- This is the area where all that makes us human resides. Thinking, consciousnesses, talking, eating, and creating.
- Estimates suggest we have 86 billion (yes, with a B) neurons and glia cells.
CORTEX – Consists of four lobes.
FRONTAL LOBE – Contains the motor cortex and key command centers for the body.
PARIETAL LOBE – Processes sensory data from the body.
TEMPORAL LOBE – Processes auditory, smell, and taste information.
OCCIPITAL LOBE – Processes visual information.
- Our brains are still developing well into our 20s.
Under the cerebral cortex are other key forebrain structures:
HYPOTHALMUS – Controls the activity of the pituitary gland.
PITUITARY GLAND – Releases hormones and correspondingly regulates all of our motivated behaviors.
THALMUS – relays information from the brain stem to the entire cerebral cortex. The temporal lobe houses the hippocampus and amygdala, two structures making up the LIMBIC SYSTEM.
AMYGDALA – Produces fear, escape, rage, and aggression.
SPINAL CORD – Extends from the base of the skull to the tailbone, and in cross-section resembles a gray X. The gray matter consists of cell bodies of neurons and is surrounded by bundles of white axons.
Bundles of AXONS are referred to as tracts (in the CNS) and nerves (in the peripheral nervous system).
Bundles of cell bodies** are referred to as **Nuclei (in the CNS) and ganglia (in the peripheral nervous system).
- Sensory information from the peripheral nervous system travels up the tracts in the CNS to the brain.
Peripheral Nervous System
PERIPHERAL NERVOUS SYSTEM – Transmits information to the entire body with 12 pairs ofCRANIAL NERVES and 31 pairs of SPINAL NERVES(one pair leaving the spinal cord at each of the vertebra in our spines). The two nerves comprising a pair serve each side of the body.
Two Main Divisions:
SOMATIC NERVOUS SYSTEM – Controls the skeletal muscles and is under conscious control.
- You can decide to move your arm to prop this book up higher, and then you can do it.
AUTONOMIC NERVOUS SYSTEM – Coordinates muscles not under your voluntary control and acts automatically in response to signals from the CNS.
- Your heart muscles, for example, are under autonomic control.
- An arm of the autonomic system called the:
SYMPATHETIC NERVOUS SYSTEM (SNS) – Produces the speeding up responses.
PARASYPATHETIC NERVOUS SYSTEM (PNS) – Produces the slowing down responses.
Endocrine System
ENDOCRINE SYSTEM – The main way the body’s functions are regulated. It is aa separate system from the nervous system.
- Why should you care about the endocrine system? One word: diabetes.
- Both forms of diabetes are a result of the body’s cells not taking in enoughINSULIN.
INSULIN – Hormone produced in the pancreas that regulates glucose uptake.
- Insulin and a host of other hormones regulate a number of the body’s activities and are secreted by the ENDOCRINE GLANDS.
Key Components and Mechanics – The key players in the endocrine system are the hormones and the ductless glands that produce them.
The Major Glands:
PITUITARY GLAND – Oxytocin
PINEAL – Melatonin
THYROID – Thyroxine
PARATHYROID – Parathyroid Hormone
THYMUS – Thymosins
PANCREAS – Insulin
ADRENAL – Cortisol and Catecholamines
OVARIES – Estrogen
TESTES – Androgens
GONADS – Collectively, the ovaries and testes.
- Are also our primary reproductive organs.
- The effect of one hormone can counteract the effect of another (e.g., glucagon and insulin).
- Sometimes, two hormones are needed to interact to cause an effect (e.g., lactation from prolactin, oxytocin, and estrogen).
- There is even a warm-up act function: One hormone serves to start a process that is finished by another hormone (e.g., implantation of a fertilized egg after the uterus is exposed to estrogen then progesterone).
Hormones are Divided Into Two Major Categories:
STEROIDS – Such as estrogens, testosterone, progesterone, aldosterone.
CORTISOL; and NONSTEROIDS – sSch as the amines (e.g., norepinephrine and epinephrine), peptides (e.g., oxytocin), proteins (e.g., insulin and prolactin), and glycoproteins (e.g., follicle stimulating hormone).
- The steroid hormones are synthesized from cholesterol whereas the nonsteroids are derived from amino acids.
HYPOTHALAMUS and the PITUITARY GLAND – Are the major controllers of the different endocrine glands.
- The hypothalamus and the pituitary gland interact to control secretion of hormones, nicely illustrating the partnership between the nervous and endocrine systems.
- In fact, the two systems are often referred to as one neuroendocrine system.
The glands of the endocrine system secrete hormones directly into the bloodstream by which they are circulated to different parts of the body.
- Just like the lock-and-key mechanisms of our brain chemicals, NEUROTRANSMITTERS – hormones are also specialized to connect to unique receptors on target cells.
- When we eat, the pancreas secretes insulin that stimulates the uptake of glucose by muscles and fat cells. Insulin lowers the glucose level in the blood. Between meals our body’s cells use up glucose and as the blood glucose decreases, the pancreas secretes glucagon, which breaks down amino acids and glycogen to increase the glucose level in the blood.
DIABETES MELLITUS – When the body cannot produce enough insulin or when the insulin target cells cannot react to it.
Diabetes can be of two forms:
TYPE 1 or Insulin Dependent Diabetes – Insulin-producing cells are destroyed.
- 10% of diabetics.
- This form is seen at an early age and is treated with insulin injections.
TYPE 2 DIABETES – Insulin levels are close to normal but the receptor cells cannot properly respond to insulin.
Diabetes is a classic example of why the biopsychosocial model in health psychology is so important and shows the relevance of culture.
- Biology interacts with psychological moods and health behaviors such as eating, which in turn are influenced by societal norms.
- Compared with non-Hispanic White adults, the risk of diagnosed diabetes was 18% higher among Asian Americans, 66% higher among Hispanics/Latinos, and 77% higher among non-Hispanic Blacks.
- Close to 20% of American Indians, 15% of African Americans, and 14% of Hispanic Americans have diabetes, only 8% of European Americans have diabetes.
- Bad diet is a direct risk factor for diabetes,
- Smoking is a major factor as well.
- Tobacco users have a 44% higher chance of developing type 2 diabetes.
- In addition to insulin, another hormone that has implications for mental and physical health is melatonin.
MELATONIN – Produced by the pineal gland, melatonin affects the reproductive cycle and how we sleep.
- Not receiving enough sunlight can cause SEASONAL AFFECTIVE DISORDER (SAD), which can be alleviated by controlling levels of melatonin.
Circulatory System
CIRCULATORY SYSTEM – The mechanisms that provide every cell in our body with life-giving oxygen.
KEY COMPONENTS:
- The circulatory system is so named because the blood flows in a circle.
- The heart, arteries, veins, and capillaries are the key components of the system.
PERICARDIUM – A fibrous sac that protects the heart.
- The human heart with its muscular myocardium walls is about the size of a clenched fist, sits just beneath our breastbone, and is protected by a fibrous sac called the pericardium.
- The right half receives blood low in oxygen from all over the body and pumps it to the lungs.
- The left half receives blood rich in oxygen from the lungs and pumps it back all over the body.
- Each half of the heart is further divided into two chambers.
ATRIA – The upper and thinner-walled chambers on each side.
VENTRICLES – lower, thicker-walled chambers on each side.
ARTERIES – Blood vessels that carry blood away from the heart.
VEINS – Vessels that carry blood to the heart.
Two large veins:
SUPERIOR – From the upper parts of the body.
INFERIOR VENA CAVAE– From the lower parts of the body.
- A large artery carries oxygenated blood to the rest of the body.
- Two other vessels carry blood between the heart and the lungs.
PULMONARY ARTERY – Carries deoxygenated blood from the heart to the lungs.
PULMONARY VEIN – Carries blood from the lungs to the heart.
- A system of valves ensures that the blood flows in one direction only.
- Each valve consists of flaps of connective tissue; the actual sound of a heartbeat is the sound of the valves closing.
- The first sound is buh, which is when the valves between the atria and ventricles close.
- The second sound is bub and is when the valves between the ventricles and the arteries shut.
Mechanics of Circulation
MECHANICS OF CIRCULATION:
- humans have what is called DOUBLE CIRCUIT CIRCULATION.
- Deoxygenated blood from all over the body flows into the heart, from where it is pumped to the lungs.
- In the lungs, the carbon dioxide in the blood is removed and oxygen flows into the blood in the tissues and air sacs of the lungs.
- The blood then flows back to the heart and is pumped to the rest of the body.
PULMONARY CIRCULATION – The circuit between the heart and the lungs.
SYSTEMIC CIRCULATION – The circuit around the rest of the body.
ARTERIOLES – As the arteries leave the heart, they get narrower and branch out many times into smaller vessels called arterioles.
CAPILLARIES – They then narrow into even finer vessels called capillaries.
VENULES – Veins similarly branch into smaller vessels, called venules.
CAPILLARIES – And into even smaller vessels also called capillaries.
- Is this the same word? Yes, it is, and the same location too. Because the blood vessels all form one giant circle, they must meet somewhere, and that place is the capillaries.
- Oxygen slips out of the capillaries and into the surrounding cells and tissues, and carbon dioxide and other cell wastes slip in.
- The blood then moves from the capillaries into the veins and back to the heart to be rejuvenated.
- The main function of the heart is to help put oxygen into the blood and to push the blood around the body to the places where it is needed.
- When the heart beats, it pumps blood to the arteries. Because the diameters of the vessels near the heart are much larger than the diameters of the arteries that the blood is being pumped into, there is pressure in the arteries.
- The arteries also influence this blood pressure as they resist the blood flow.
- Healthy arteries are muscular and elastic.
- They stretch when your heart pumps blood through them, with more stretching being produced by stronger pumping.
- The pressure rises with each beat and falls in between beats as the heart muscles relax.
Process of Pumping is a Two-Stage Process:
- Consisting of a cycle of contractions by different parts of the heart.
- In the first stage, the atria contract and the ventricles relax.
- In the second stage, the reverse takes place.
- The heart beats between 55 and 85 times per minute when you are at rest, but the rate of beating can change dramatically with each different move.
- Can even change from minute to minute, depending on what you are thinking.
- Blood pressure is described using two numbers:
SYSTOLIC PRESSURE – When the heart is beating.
DIASTOLIC PRESSURE – When the heart is resting.
- Measured in millimeters of mercury (mm Hg), which is the height in millimeters of mercury that the pressure could support.
- A healthy adult’s blood pressure should be less than 120/80 mm Hg.
Biological Primer
BIOLOGICAL PRIMER:
- In discussing cardiovascular diseases (CVDs) and reading the medical literature, you will probably encounter many technical terms with which you need to be familiar.
ANGINA PECTORIS – (Chest pain) is a common symptom of heart attacks.
MYOCARDIAL INFRACTION – Called cardiac arrest.
MYOCARDIUM – Is the medical term for the muscle of the heart.
ISCHEMIA – Term for the condition in which blood flow is limited in a certain part of the body.
MYOCARDIAL ISCHEMIAS – Heart attacks, although, more specifically, heart attacks result from ischemias to the cardiac region.
Digestive System
DIGESTIVE SYSTEM:
- What you eat can have serious implications for your health.
- Your diet also is linked to your likelihood of being diabetic and developing coronary heart disease and can influence how you cope with cancer.
- Diet high in fat and cholesterol is a major contributor to obesity.
Key Components and Mechanics of the DIGESTIVE SYSTEM:
DIGESTIVE SYSTEM – Essentially a tube with two openings.
- We take in food through our mouths and, well, you know how we excrete what is left of it.
GASTROINTESTINAL TRACT (GI) – The entire span from mouth to anus.
- Food moves from the mouth through the THROAT and PHARYNX into the ESOPHAGUS and then into the STOMACH.
- The food moves into the SMALL INTESTINES, which totals almost 20 feet in length and is all wound up in our body cavity. The last part of the GI tract is the LARGE INTESTINE, or COLON, which terminates in the RECTUM and ANUS.
- Chewing and salivary enzymes begin breaking down food in the mouth.
- In the stomach, gastric fluids start digesting proteins.
- Secretions from the liver, gallbladder, and pancreas act on food in the small intestine where nutrients are absorbed.
- The entire inner length of the small intestine comprises many circular folds that greatly increase its surface area to optimize nutrient absorption.
- The large intestine stores undigested matter for excretion.
- In addition to obesity, other major health problems related to the digestive system are:
- GASTROENTERITIS
- DIARRHEA
- LACTOSE INTOLERANCE
HEMORRHOIDS
GALLSTONES
IRRITABLE BOWEL SYNDROME
ULCERATIVE COLITIS
- Sixty to 70 million people are affected by digestive diseases.
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ALCOHOLISM:
- Alcohol is processed through the liver and excessive alcohol use can damage the liver, which is why alcoholics often develop liver disease.
- LIVER CIRRHOSIS – One of the ten leading causes of death in the United States.
BARIATRIC SURGERY – Most common type is gastric bypass surgery, which is the stapling of the stomach to create a smaller pouch. A section of the small intestine is then cut out. This bypass of sections of the intestine cuts down on how many nutrients are absorbed.
RENAL/URINARY SYSTEM – Handle metabolism and excretion of wastes.
- Major components of the renal system are the KIDNEYS, URETERS, URINARY BLADDER, and URETHRA.
KIDNEY – Contains blood vessels and tubes called nephrons. The nephrons filter water and substances such as urea and sodium out of the blood and produce urine.
- The contents of your urine provide important insights into your health. If you are stressed, your urine will show high levels of cortisol and other stress hormones.
- The body maintains a balance between acidity and alkalinity with the aid of the renal system. If the blood stream is too acidic, the urine will be acidic. If you are diabetic, your urine will have high levels of glucose.
Physiology of Immunity
PHYSIOLOGY of IMMUNITY:
IMMUNE SYSTEM – The component of our bodies that protects us from threats, mostly in the form of bacteria and germs.
- Immune system serve two main functions:
- To discriminate what constitutes our bodies from what are foreign substances.
- To destroy and clear those foreign substances and infected cells.
Large portion of health psychological research focuses on the interface between psychological factors and the working of the immune system.
- The immune system has a network of capillaries, the LYMPHATIC SYSTEM, and small oval bodies called LYMPH NODES.
LYMPHATIC CAPILLARIES – Lie along blood vessels and carry a colorless fluid called lymph that is composed of fats, proteins, and water and holds the key cells of the immune system.
LYMPH NODES – Serve as a filtering system and are packed with leukocytes.
LEUKOCYTES – White blood cells (WBCs). Filter microorganisms and other particles from the lymph and greatly reduce our risks of infection.
THREE MAIN TYPES of LEUKOCYTES:
POLYMORPHONUCLEAR GRANULOCYTES – The most common (comprising between 50% and 70% of leukocytes).
- While common, polymorphonuclear granulocytes play a minor role in psychoneuroimmunology and have proven difficult to study. Therefore, we do not discuss them in detail in this book.
LYMPHOCYTES – The most important leukocytes comprise 20% to 40% of leukocytes (Freberg, 2016). These are the true fighters of the immune system.
- Three Main Types of Lymphocytes:
- Two of which:
- T CELLS** and **B CELLS – Are further subdivided into more types.
- T cells and B cells are both formed in the bone marrow, but each type of cell is conveniently named based on where the cells mature.
- T cells mature in the thymus gland, an organ situated at the base of the neck
- Thymus is the main site for T-cell development. It is prominent when we are young but shrinks after we reach puberty.
There are three main types of T cells.
- The workhorses are the T cytotoxic cells, or** **Tc cells. These cells are responsible for killing virally infected cells.
Helper T Cells, or Th Cells – These cells enhance the functioning of other T cells and play a role in the maturation of B cells.
- They serve as sentinels, prowling through our bloodstreams looking for invaders.
- When they encounter foreign cells, germs, or bacteria, they secrete chemical messengers that draw other types of immune cells to the location and destroy the invaders.
- Th cells are some of the most common T cells, comprising 30% to 60% of T cells.
Suppressor T Cells, or Ts Cells – These cells slow down the functioning of the immune system and prevent the body from damaging itself.
- In particular, once foreign germs have been eliminated, the T s cells secrete chemicals to turn off the action of Tc and TH cells.
B CELLS:
- Are both born in and mature in the bone marrow.
ANTIBODY-PRODUCING B CELL – Forms specific substances earmarked for specific germs or antigens.
MEMORY B CELL – Memory B cells are cells that form a template or identification for invading antigens.
- The one that explains why so many of us are subjected to immunizations and vaccinations during childhood.
- Memory B cells circulate in the body for many years after an antigen has been eliminated, ready to identify it if it were to invade the body again.
- By having this indicator of the antigen, illness is less likely to recur because the moment we are infected by the antigen, the memory B cells recognize it and activate our bodies’ defenses.
Third kind of lymphocyte is the:
NATURAL KILLER (NK) CELL – These cells circulate in the body, playing a role in different immune responses and especially in destroying diseased cells by injecting them with toxic chemicals.
The foot soldiers of the effort, and often those at the forefront of defenses, are:
MONOCYTES – (circulating in the lymphatic system)
MACROPHAGES – (A type of monocyte found in the tissue). These cells are the first to attack germs or foreign invaders, destroying them by engulfing and devouring them.
- MONOCYTES and MACROPHAGES – The least common cells.
INTERLEUKIN-1 and 2 – Important immune system components are the chemical messengers.
INTERFERON – Chemical that prevents viral infections from spreading.
SPLEEN – Ductless organ in the upper left of our abdomen which serves as a filter for blood.
TONSILS – Their primary function is the storage of lymphocytes.
Three main types of White Cells:
LYMPHOCYTES, LEUKOCYTES, and MONOCYTES
LYMPHOCYTES – Originate in the bone marrow and mature there or in the thymus—hence the names B-lymphocytes and T- lymphocytes.
B-CELLS – Produce antibodies, chemicals that disable invading microorganisms.
T-CELLS – Attack other cells infected with viruses directly.
Process of Defense
PROCESS OF DEFENSE:
- Our primary foes are microorganisms such as bacteria and viruses.
- The main lines of entry for foreign invaders are the skin and the different openings of the body: the nasal passage and mouth, walls of the stomach and intestine), and the sexual and excretory organs.
- We have a number of basic processes that protect us at each of these points:
- We secrete mucus to trap germs and prevent their entry.
- We cough to get germs out of our lungs.
- Our skin also has a number of glands that secrete a mild oily substance called sebum that also serves to prevent microorganisms from breaking the skin barrier or from growing on the skin.
- Most microorganisms do not get past the barrier of the thick pile of cell layers that make up the epidermis.
- The outer layer consists of nondividing cells, many of which are dead or dying, that protect the dividing skin cells beneath.
NONIMMUNOLOGIC DEFENSES – Even when germs do enter the body on particles of food or dust, they usually die due to exposure to lysozyme, an enzyme found in saliva and tears, which digests the cell walls of many microorganisms. These barriers do not rely on the cells of the immune system and are referred to as nonimmunologic defenses.
