Chapter 27: Human Body Organization

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Questions and Answers

What is the primary function of lysozyme in tears?

To stimulate the release of histamines from mast cells

To break down bacterial cell walls (correct)

To produce antibodies against pathogens

To increase the body's temperature

What is the primary mechanism by which the inflammatory response fights pathogens?

By engulfing and destroying bacteria through phagocytosis (correct)

By releasing chemicals that increase the body's temperature

By releasing histamines that increase blood flow to affected areas

By stimulating the release of antibodies against pathogens

What is the primary function of the immune system's specific defenses?

To stimulate the release of histamines from mast cells

To break down bacterial cell walls

To distinguish between 'self' and 'other' cells (correct)

To increase the body's temperature

What is the primary function of antigens in the immune response?

To stimulate the immune response by recognizing foreign substances Signup and view all the answers

What is the primary function of vaccines in the immune response?

To take advantage of antigens and immunological memory Signup and view all the answers

What is the primary function of B cells in the immune response?

To produce antibodies against specific pathogens Signup and view all the answers

What is the primary difference between humoral immunity and cell-mediated immunity?

Humoral immunity depends on the action of antibodies, while cell-mediated immunity depends on the action of T cells Signup and view all the answers

What is the primary result of problems with immune system function?

Allergies and autoimmune diseases Signup and view all the answers

Which of the following is a common symptom of an allergy?

Watery eyes and runny nose Signup and view all the answers

What is the primary function of antihistamines in relation to allergy symptoms?

To counteract the effects of allergens Signup and view all the answers

Which of the following can trigger asthma symptoms?

Respiratory infections, exercise, stress, and allergens Signup and view all the answers

What is the primary cause of autoimmune diseases?

The immune system's attack on the body's own cells Signup and view all the answers

What is the primary difference between HIV and AIDS?

HIV attacks the immune system, while AIDS is a symptom of HIV Signup and view all the answers

How is HIV typically transmitted?

Through sexual intercourse with an infected person, sharing needles with an infected person, contact with infected blood or blood products, and transmission from infected mother to child during pregnancy, birth, or breast feeding Signup and view all the answers

What is the best way to avoid HIV infection?

Abstaining from sexual activity and avoiding illegal intravenous drug use Signup and view all the answers

What is the current status of a cure or reliable vaccine for AIDS?

Neither a cure nor a reliable vaccine is available Signup and view all the answers

What is the genetic material carried by HIV?

RNA Signup and view all the answers

What is the primary function of the liver in terms of glucose regulation?

To remove excess glucose from the bloodstream Signup and view all the answers

Which of the following types of blood vessels has thin walls that allow oxygen and nutrients to diffuse into tissues and carbon dioxide and waste products to move into the bloodstream?

Capillaries Signup and view all the answers

What is the primary function of the hypothalamus in terms of thermoregulation?

To monitor and regulate body temperature Signup and view all the answers

What is the term for the process in which the body maintains a controlled, stable internal environment despite changes in the external environment?

Homeostasis Signup and view all the answers

Which of the following is NOT a function of the lymphatic system?

To produce red blood cells Signup and view all the answers

What is the primary function of the kidneys in terms of excretion?

To remove waste products from the bloodstream and excrete them in the urine Signup and view all the answers

What is the term for the process in which the body's internal environment is monitored and adjusted to maintain a stable state?

Homeostasis Signup and view all the answers

What is the primary function of the skin in terms of excretion?

To remove excess salts and water through sweat Signup and view all the answers

Study Notes

Organization of the Human Body

Human body is composed of cells, tissues, organs, and organ systems
Cells are the basic units of structure and function, and they tend to be specialized in multicellular organisms
Tissues are groups of cells that perform a single function
- Epithelial tissue lines interior and exterior body surfaces
- Connective tissue provides support for the body and connects its parts
- Nervous tissue transmits nerve impulses throughout the body
- Muscle tissue makes movements of the body possible
Organs are groups of different types of tissues that work together to perform a single function or several related functions
Organ systems are groups of organs that perform closely related functions

Homeostasis

Homeostasis is the process of maintaining a controlled, stable internal environment
Feedback inhibition is a process in which a stimulus produces a response that opposes the original stimulus
Organ systems keep internal conditions within a certain range
Example: hypothalamus monitors body temperature and responds to changes by sending signals to cells to speed up or slow down their activities

Liver and Homeostasis

Liver regulates the level of glucose in the blood
After a meal, glucose in the blood rises, and the liver takes glucose out of the blood to keep it from rising too much
As the body uses glucose for energy, the liver releases stored glucose to keep the level of sugar from dropping too low

Human Systems

Digestive System

Converts food into small molecules that can be used by cells of the body
Digestion is the breakdown of food into smaller molecules
- Mechanical digestion: physical breakdown of large food pieces into smaller pieces
- Chemical digestion: enzymes break down food molecules
Absorption: nutrients are absorbed into the bloodstream
Elimination: waste products are eliminated from the body

Excretory System

Excretes metabolic wastes from the body
Skin: removes excess water, salts, and small amounts of urea in sweat
Lungs: removes carbon dioxide from the body
Liver: converts nitrogen-based wastes into less toxic compounds
Kidneys: remove excess water, urea, and metabolic wastes from the blood
Urine: produces and excretes urine

Circulatory System

Transports oxygen, nutrients, and other substances throughout the body, and removes wastes from tissues
Heart: pumps blood throughout the body
Blood: carries oxygen, nutrients, and other substances throughout the body
Circulation: heart functions as two pumps, one pushing blood to the lungs and the other pushing blood to the rest of the body

Blood

Human body contains approximately 4-6 liters of blood
Plasma: 55% of blood, 90% water, and 10% dissolved gases, salts, nutrients, enzymes, and proteins
Red blood cells: transport oxygen
White blood cells: fight viral and bacterial infections
Platelets: necessary for blood to clot

Lymphatic System

Network of vessels, nodes, and organs that collects lymph that leaves capillaries, "screens" it for microorganisms, and returns it to the circulatory system
Role in circulation: collects lymph from capillaries and returns it to the bloodstream
Role in immunity: traps microorganisms, stray cancer cells, and debris
Thymus and spleen play roles in immune functions

Respiratory System

Picks up oxygen from the air and releases carbon dioxide
Air flow: air enters the respiratory system through the nose, mouth, and sinuses
Gas exchange: oxygen diffuses into the bloodstream, and carbon dioxide diffuses out of the bloodstream
Breathing: diaphragm and chest muscles contract and relax to bring air into and out of the lungs

Immunity and Disease

Infectious diseases: caused by viruses, bacteria, fungi, and other pathogens
Spread of infectious diseases: through coughing, sneezing, physical contact, and contaminated water and food
Nonspecific defenses: skin, tears, and other secretions; inflammatory response, and fever### First Line of Defense
Tears contain lysozyme, an enzyme that breaks down bacterial cell walls.
Stomach secretions destroy many pathogens in food and water.

Second Line of Defense

Inflammatory response causes infected areas to become red, painful, or inflamed.
Mast cells release histamines, increasing blood flow to affected areas.
White blood cells move into infected tissues, engulfing and destroying bacteria.
The immune system releases chemicals that increase body temperature, producing fever.
Increased body temperature may slow down or stop the growth of some pathogens.
Higher temperature helps speed up the immune response.

Specific Defenses

The immune system distinguishes between "self" and "other," inactivating or killing foreign substances or cells.
"Self" cells carry chemical markers that act as passwords.
When the immune system recognizes a bacterium or virus as "other," it uses cellular and chemical weapons to attack.
The immune system "remembers" invaders, enabling a more rapid and effective response if the same pathogen attacks again.

Antigens and Vaccines

Antigens are foreign substances that can stimulate an immune response.
Antigens are molecules on the outer surfaces of bacteria, viruses, and parasites.
The immune system responds to antigens by producing cells that attack invaders directly or that produce proteins called antibodies that tag them for destruction.
Vaccines work by taking advantage of antigens and immunological memory.
Vaccines contain antigens of pathogens that cause diseases, such as smallpox, diphtheria, and polio.

Fighting Infections

The main working cells of the immune response are B lymphocytes (B cells) and T lymphocytes (T cells).
B cells are produced in the bone marrow, while T cells are produced in the bone marrow but mature in the thymus.
Each B and T cell is capable of recognizing one specific antigen.
The specific immune response has two main styles of action: humoral immunity and cell-mediated immunity.
Humoral immunity depends on the action of antibodies that circulate in the blood and lymph.
Cell-mediated immunity defends the body against some viruses, fungi, and single-celled pathogens.

Immune System Disorders

Problems with immune system functions can result in allergies, asthma, autoimmune disease, and AIDS.
Allergies occur when antigens trigger inflammatory responses, such as sneezing, watery eyes, and runny nose.
Allergens can trigger allergic reactions, and antihistamines can relieve symptoms.
Asthma is characterized by narrow air passages, causing wheezing and difficulty breathing.
Inhaled medications can relax smooth muscles around airways and relieve asthma symptoms.
Autoimmune diseases occur when the immune system attacks the body's own cells.
Type I diabetes is an autoimmune disease in which the immune system attacks insulin-producing cells in the pancreas.
HIV and AIDS are caused by HIV, which attacks key cells within the immune system, leaving the body with inadequate protection against pathogens.
HIV is a retrovirus that carries its genetic information in RNA, rather than DNA.
Over time, HIV destroys T cells, crippling the immune system's ability to fight HIV itself and other pathogens, leading to AIDS.

HIV Transmission and Prevention

HIV is transmitted through: sexual intercourse with an infected person, sharing needles with an infected person, contact with infected blood or blood products, and transmission from an infected mother to a child during pregnancy, birth, or breastfeeding.
The best way to avoid HIV infection is through abstinence from sexual activity and avoidance of illegal intravenous drug use.
There is no cure or reliable vaccine against AIDS.

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Explore the organization of the human body, from cells to organ systems, and understand the levels of organization and specialization in multicellular organisms.