Nonspecific Immunity Response

• Immunity is a series of defenses that involves both nonspecific and specific attacks on pathogens.
• A pathogen is a foreign organism, like a virus or fungus, that causes disease and disrupts homeostasis.

Nonspecific Immunity Response

• The body has multiple defenses in the immune system.
• These defenses are nonspecific as they are not targeted at a specific pathogen.
• Nonspecific defenses help prevent disease and slow its progression.
• The first line of defense attempts to keep foreign invaders out of the body.
• Dead skin cells protect against microorganism invasion.
• Saliva, tears, and nasal secretions contain enzymes that break down bacterial cell walls, killing pathogens.
• The second line of defense involves nonspecific immune responses to pathogens that bypass the first line of defense.
• These responses include fever, inflammatory response, and cellular defenses like phagocytes.
• An inflammatory response increases blood flow to the infected area, making blood vessels more permeable for white blood cells to escape.
• Phagocytosis is the process by which phagocytic cells surround and consume foreign microorganisms.
• Phagocytes release digestive enzymes and harmful chemicals from their lysosomes to destroy microorganisms.

Specific Immune Response & WBCs

• The immune system is a group of organs that work together to fight infections, diseases, and pathogens.

• Functions of the lymphatic system/immune system include:

  • Filter out pathogens from lymph fluid
  • Drain extra lymph fluid to prevent swelling
  • Destroy foreign microorganisms

• Lymph is the clear fluid in the lymphatic system that carries cells to fight infections.

• Lymphatic organs include lymphatic tissue, lymphocytes, lymph nodes, tonsils, spleen, thymus gland, and bone marrow.

• Specific immunity is an immune response that attacks specific pathogens.

• Pathogens can be recognized by their antigen.

• Pathogens contain surface proteins called antigens.

• Antigens are chemical markers (name tags) that identify the pathogen.

• Each pathogen has a unique antigen.

• White Blood Cells (WBCs) fight infection by destroying foreign substances (antigens) or pathogenic cells; they act as soldiers of the defense system.

• An antigen is a unique protein found in pathogens.

• An antibody is a molecule produced by WBCs that attaches to antigens of invading pathogens.

• B-cells make antibodies for specific pathogens/antigens.

• T-cells recognize and kill specific pathogen/infected cells.

• Red blood cells carry oxygen to body cells and carry carbon dioxide to the lungs.

• White blood cells fight infections by destroying antigens.

Active and Passive Immunity

• Passive immunity involves obtaining antibodies from an external source and provides immediate but temporary protection.
• Breast milk is an example of passive immunity.
• Active immunity occurs when you make antibodies in response to an antigen, resulting in permanent protection due to immunological memory.
• Natural exposure to a pathogen or a vaccine can result in active immunity.
• Vaccines involve the injection of a dead or weakened pathogen to stimulate WBC antibody production.
• Antibiotics are chemical substances naturally produced by microorganisms.
• Antibiotics function to inhibit (stop) the growth of, or destroy bacteria
• Avoid antibiotic overuse to preserve their effectiveness.
• Overusing antibiotics can lead to some bacteria (“superbugs”) becoming resistant.
• Herd immunity is indirect protection from an infectious disease.
• A population develops herd immunity through vaccines or previous infections.

Disorders of the Immune System

• Allergy is when the immune system reacts overly sensitive to a normally harmless substance.
• Allergens cause histamine to be produced, leading to itching, swelling, and rash.
• AIDS is a disease caused by HIV (Human Immunodeficiency Virus).
• HIV is transmitted through bodily fluids such as blood, semen, and vaginal fluids.
• The HIV virus attacks WBCs (specifically T-cells), which are essential for immune response.
• This weakens the immune system and prevents the infected person from fighting other infections like pneumonia or a cold
• Autoimmune diseases occur when the immune system attacks the body's own cells.
• There are over 60 autoimmune diseases include diabetes.

Infectious Diseases & Transmission

• An infectious disease is caused when a pathogen is passed from one organism to another.
• Types of pathogens that cause infectious diseases include viruses, bacteria, fungi, protozoans, and parasites.
• A disease reservoir is a source of the pathogen in the environment.
• Reservoirs can be animals, people, or nonliving objects like soil or contaminated food/water.
• Humans are the main reservoir for pathogens that affect humans.
• Asymptomatic individuals can transmit pathogens. An asymptomatic individual is called a carrier.
• Animals can also be reservoirs of pathogens that can be passed to humans.
• Pathogens can be spread through direct contact, indirect contact from the air, indirect contact from objects, and vectors.
• Direct contact involves body-to-body contact like handshakes or hugs.
• Indirect contact from the air occurs via coughing and sneezing, which eject droplets containing pathogens.
• Indirect contact from objects involves physical contact with contaminated inanimate objects like doorknobs or phones.
• Vectors are animals that transport pathogens from one host to another; mosquitoes transmit malaria through their bite.

Homeostasis & Feedback Mechanisms

• Homeostasis is the ability of an organism to maintain a relatively stable internal environment despite external changes.
• The body monitors itself to maintain homeostasis.
• When a system is off-balance, the body initiates metabolic processes to restore balance.
• External stimuli like heat, cold, lack of oxygen, pathogens, or toxins disrupt homeostasis.
• Internal stimuli such as body temperature, blood pressure, and concentrations of water, glucose, and oxygen disrupt homeostasis.
• Physical and psychological distress also disrupt homeostasis.
• Negative feedback loops maintain a variable (e.g., body temperature, blood glucose) close to a set point by "shutting off" or "turning on" a system.
• Negative feedback loops stop once homeostasis is reached.
• Negative feedback examples are thermostat, thermoregulation of body temperature, and regulation of blood glucose.
• Positive feedback loops increase the likelihood of an event to continue.
• Examples of positive feedback are contractions during childbirth, torn vessel releasing clotting factors, and growth hormones stimulating cell division.

Nervous System & Endocrine System

• The nervous system controls voluntary and involuntary functions through nerve impulse conduction (electric signals).
• The endocrine system controls body functions through chemical signals (hormones).
• Both systems allow responses to stimuli.
• A stimulus is something that causes a response that can be chemical, cellular, or behavioral.
• The nervous system controls and coordinates body functions.
• The nervous system responds to internal and external stimuli.
• The brain, spinal cord, and nerves compose the nervous system.
• The functional unit of the nervous system is the neuron.
• A nerve is an organ containing a bundle of nerve cells called neurons.
• A neuron is a specialized cell that stores information and carries messages.
• A neuron has a cell body, dendrites, and an axon.
• The cell body contains the nucleus and organelles.
• Dendrites are branch-like extensions that receive messages.
• An axon is a long extension that carries electrical messages away from the cell body.
• Sensory neurons detect stimuli and transmit signals to the brain and spinal cord.
• Interneurons make up the brain and spinal cord and receive and process information.
• Motor neurons pass messages from the nervous system to organs and muscles.
• Neurons transmit information in the form of electrical and chemical impulses.
• When stimulated, neurons produce an electrical impulse that travels along its length.
• Communication between neurons is facilitated with neurotransmitters.
• Chemical messengers called neurotransmitters are released by one neuron to relay a message to the next, since neurons do not physically touch.
• Reflex arcs are involuntary movements that allow quick reactions to protect from injury.
• IV. Central and Peripheral Nervous Systems (29.4)
• The nervous system's two parts work together
• CNS includes brain and spinal cord composed of interneurons
• PNS is collection of nerves that connects the CNS to all of your organ system
• The brain contains over a 100 billion neurons.
• The brain is protected by three layers of connective tissue (meninges) and fluid.
• Fluid is found between layers that help cushion brain
• The spinal column consists of vertebrae, fluid, meninges, and the spinal cord.
• The spinal cord connects the brain to the nerves throughout the body
• The Peripheral Nervous System (PNS) is a network of nerves that transmit messages to and from the Central Nervous System
• The Peripheral Nervous System (PNS) consists of a network of nerves that transmit messages to CNS and from CNS to other organs in body.
• The endocrine system consists of slower-acting chemical signals carried in the bloodstream.
• It controls long-term processes like hair growth and aging.
• The endocrine system helps regulate homeostatic functions like body temperature.
• It consists of glands that release hormones into the bloodstream for cellular communication.
• Glands release hormones into the bloodstream.
• Hormones are chemicals produced by endocrine glands.
• The hypothalamus is a small gland found in the brain.
• It makes hormones to stimulate the pituitary gland to release hormones.
• The hypothalamus acts as part of both the CNS and endocrine systems.
• The hypothalamus receives, sorts, and interprets information from sensory organs as part of the CNS.
• The hypothalamus produces releasing hormones as part of the endocrine system that affect tissues and other endocrine glands.
• The pituitary gland, also known as the "Master" Gland, is a pea-sized gland at the base of the brain.
• It stimulates other endocrine glands and produces growth hormones (GH).
• The thyroid gland is a butterfly-shaped gland in the neck.
• It regulates cell metabolism, growth, and development.
• The thymus is within the chest area and causes white blood cells to mature and help fight infection.
• The adrenal glands are above the kidneys.
• They secrete adrenaline and epinephrine, which increase heart rate, dilate pupils, and increase blood vessel diameter ("fight or flight" response).
• The pancreas is behind the stomach.
• It makes digestive enzymes and produces insulin and glucagon to regulate sugar levels in the bloodstream.
• The gonads are the ovaries in women and testes in men.
• Ovaries release estrogen and progesterone to regulate the menstrual cycle and secondary sex characteristics.
• Testes release testosterone to regulate secondary sex characteristics.
• Target cells are cells with specifically shaped receptors for receiving certain hormones.

Endocrine System Disorders

• Pituitary gland disorders include Gigantism and Hyposecretion resulting in dwarfism
• Gigantism results from excessive production of growth hormone from the pituitary gland.
• Hyposecretion of hormones leads to dwarfism.
• The thyroid disorders are Hyperthyroidism, Goiter, and Hypothyroidism.
• Hyperthyroidism occurs when the thyroid produces excessive amounts of thyroxine, causing weight loss, heart palpitations, anxiety, and bulging eyes..
• A goiter is an enlargement of the thyroid due to lack of iodine in the diet.
• Hypothyroidism occurs when the thyroid produces inadequate amounts of thyroxine and results in weight gain, slow heart rate, depression, and sensitivity to cold.