Biol 3

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Respiration: Physiological process by which oxygen moves into internal environment and carbon dioxide moves out
Oxygen is needed for aerobic respiration
Carbon dioxide is produced by same
The respiratory system works hand-in-hand with circulatory system for gas exchange/flow
Also helps regulate acid/base balance
System is â€œopenâ€ to the environment and thus open to chemicals and infectious agents
Airways: Large Surface Area: Air enters through nose, moves through pharynx and larynx to trachea
Trachea branches into two bronchi
Each bronchus branches into bronchioles
Bronchioles end in alveoli where gas exchange
Speech Production: Vocal cords stretch across laryngeal opening; opening between them is glottis
Position of cords is varied to create different sounds
Pressure Gradients: Concentration gradients exist for both oxygen and carbon dioxide in the body; both have a tendency to diffuse down their pressure gradients
Gases enter and leave the body by diffusing down pressure gradients across respiratory membranes
Hemoglobin aids in maintaining the gradient by pulling oxygen away from lungs
Atmospheric pressure is the pressure exerted by the weight of the air on objects on Earthâ€™s surface
At sea level = 760mm Hg
O2 is 21% of air; partial pressure is ~ 160mm Hg; partial pressure CO2 is 0.3mm Hg
When O2 is Scarce (Hypoxia): Altitude sickness
Humans are adapted to lower elevations where oxygen levels are relatively high
At high altitude, hyperventilation leads to ion imbalances in cerebrospinal fluid; increased capillary permeability can cause edema
Carbon monoxide poisoning
CO binds to hemoglobin 200 times more tightly than oxygen does
Even tiny amounts can tie up hemoglobin and prevent oxygen delivery; can be fatal
Breathing (Respiratory Cycle): Inhalation
Diaphragm flattens, external muscles contract, volume of thoracic cavity increases, lungs expand ï‚® air flows down pressure gradient into lungs
Exhalation
Normal (passive): muscles relax, thoracic cavity recoils, lung volume decreases ï‚® air flows down pressure gradient and out of lungs
Active: muscles contract, decreasing thoracic cavity volume more than passive exhalation ï‚® a greater volume of air must flow out to equalize intrapulmonary pressure with atmospheric pressure
Gas Exchange: Occurs between blood in pulmonary capillaries and air in the alveoli
Respiratory membrane is extremely thin and allows rapid diffusion of gases
Gas Transport Oxygen: Most is carried bound to hemoglobin in red blood cells
Hemoglobin has a great affinity for oxygen when it is at high partial pressure (in pulmonary capillaries), lower affinity for oxygen in tissues, where partial pressure is low
Gas Transport Carbon Dioxide: Most is transported as bicarbonate, smaller amounts are transported dissolved in blood and bound to hemoglobin
Bicarbonate formation is enhanced by the action of carbonic anhydrase inside red blood cells
Breathing rhythm:: Diaphragm and intercostal muscles under control of reticular formation; one cell cluster controls inspiration, the other expiration ï‚® the resulting rhythm is fine tuned by centers in the brain stem
Magnitude of breathing:: Receptors in medulla detect H+ and signal increases in rate and depth of breathing; Carotid bodies and aortic bodies detect CO2, oxygen, and pH to also signal increase in rate of breathing
Chemical controls: Increase in CO2 causes smooth muscle of bronchioles to dilate; decrease in CO2 causes smooth muscle of bronchioles to constrict
Bronchitis: Irritation of the ciliated epithelium that lines the bronchiole walls
Air pollutants, smoking, or allergies can be the cause
Chronic bronchitis scars and constricts airways
Emphysema:: An irreversible breakdown in alveolar walls
May be genetic defect; Most often caused by smoking
Lungs become inelastic
Asthma:: Smooth muscle ringing bronchi contracts; mucus is produced by bronchial epithelium
Can be triggered by allergens; Result is reduced air flow
Apnea:: Breathing stops and starts, more common as age
Upper RT Infections Bacterial Diseases: Strep throat, rheumatic fever, scarlet fever, ear infections following throat infections, diphtheria
Upper RT Infections Viral Diseases: Common cold (200+ different viruses can cause the common cold, including members of the adenovirus and rhinovirus groups), croup
Lower RT Infections Bacterial Diseases: Bacterial pneumonias: pneumococcal (80%), primary atypical (walking) pneumonia, legionellosis, Q fever, psittacosis, chlamydial
Other bacterial diseases: pertussis, tuberculosis, inhalational anthrax
Lower RT Infections Viral Diseases: Influenza, RSV, SARS, Hantavirus
Lower RT Infections: Histoplasmosis, blastomycosis, coccidioidomycosis (3 of the 4 actual pathogenic fungal diseases)
PCP (occurs in 90% HIV patients)
Three Lines of Defense: Barriers at body surfaces
Nonspecific responses
Immune responses
Three Lines of Defense Barriers at body surfaces: Intact skin and mucous membranes
Lysozyme
Normal bacterial flora
Flushing effect and low pH of urine
Three Lines of Defense Nonspecific responses: Lymph nodes trap and kill pathogens
White blood cells attack a range of pathogens
Inflammation
Complement
Three Lines of Defense Immune responses: T cells and B cells to attack and kill pathogens or infected cells
Communication signals and chemical weapons (antibodies)
Acute Inflammation: Nonspecific immune response to foreign invasion, tissue damage, or both; characterized by redness, swelling, warmth, and pain
Destroys invaders, removes debris, prepares area for healing
Excess inflammation is a problem in some autoimmune diseases and some infections
Features of Immune Responses: Self/non-self recognition
Recognition based on identification of â€œantigensâ€ â€“ â€œnon-selfâ€ markers on foreign agents and altered body cells such as tumors
Specificity
Recognition of an antigen leads to rounds of cell division that form huge populations of lymphocytes
Specialization of lymphocytes into effector and memory cells that have receptors for one kind of antigen
Diversity
Billions of different effector cells can be generated; effector cells engage and destroy invaders
Memory
Memory cells protect us from future recurrence of disease
Cells and Proteins MHC markers: identify â€œselfâ€ from â€œnon-selfâ€; all of your cells have 1 of 2 classes of MHC marker on their surfaces
Cells and Proteins Antigen-presenting cells: process antigens and then present (in presence of MHC) to immune cells for recognition and destruction
Cells and Proteins T cells: Helper T cells recognize Antigen-MHC presentation and stimulate further immune responses
Cytotoxic T cells and Natural Killer cells attack and destroy infected body cells, tumor cells and cells of organ transplants
Suppressor T cells turn off immune responses
Cells and Proteins B cells: produce antibodies to â€œmarkâ€ antigens, invaders and cells for destruction
Clonal Selection: B cells and T cells have antigen receptors on their surfaces; each receptor is unique for a given antigen
Receptors are produced via genetic recombination
B cells produce antibodies with specific variable regions to recognize antigens; T cells have TCRs (T-Cell Receptors)
Since each B cell and T cell is different; once recognition of an antigen occurs, the selected cell must be mass produced to allow for an immune response
Immunological Memory: During a primary immune response, large numbers of effector cells are produced along with memory cells
Only the effector cells participate in the response to clear the invader
Memory cells are held back
During subsequent exposre to the SAME antigen, memory cells specific for that antigen are quickly activated to divide and clear the invader
If the antigen is different, no recognition occurs
Antibody-Mediated Responses: Carried out by B cells
Targets are intracellular pathogens and toxins
Antibodies bind to target and mark it for destruction by phagocytes and complement
5 types of antibodies made
IgM = 1st Ab produced during response
IgG = circulating; complement, neutralization
IgA = secreted in mucus membranes; neutralization
IgD = T cell activation
IgE = allergic reactions
Cell-Mediated Responses: Carried out by T cells
Stimulated by antigen-presenting macrophages
Main target is antigen-presenting body cells (cells with intracellular pathogens) or tumor cells
Kill by releasing chemicals that cause apoptosis (programmed cell death)
Organ Transplants: Donor and recipient must share at least 75% of their MHC markers in order to be â€œcompatibleâ€
After surgery, recipient receives drugs that suppress the immune system
Because of immune system suppression, recipient must take large doses of antibiotics to prevent infections
One of the major problems with organ transplantation today is a lack of organs
Increase in â€œlivingâ€ donations and donations between strangers can lead to ethical questions
Immunology and Medicine: Immunization
Active immunization: Antigen-containing material is injected to confer long-lasting immunity
Passive immunization: Purified antibody is injected; protection is short lived
Diagnostics
Monoclonal antibodies are made by cells cloned from a single antibody-producing B cell; can be used to specifically bind to and identify antigens in patients
Immune Therapies
Interferons can be used to treat viral infections
Immune Disorders Allergies: Immune reaction to a harmless substance
Genetic predisposition: IgE responds to antigen by binding cells which then secrete histamine to cause symptoms
Severe reactions can lead to life-threatening anaphylactic shock (wasp or bee venoms usually cause this, not pollen)
Immune Disorders Autoimmune Disorders: Immune system is weak or lacking
SCID: bodyâ€™s ability to make lymphocytes is impaired or nonexistent; high vulnerability to infection
HIV/AIDS: destruction of T cells + immune function
Microbial Evasion: The immune system is a powerful protector, but microbes have many ways of evading clearance
Infection of immune cells themselves, or in other â€œprivilegedâ€ sites (effectively hide)
Destruction of immune cells
Suppression of immune responses
Molecular mimicry
Antigenic variation
Antigenic variation is of paramount threat
Influenza has different strains
Antigenic shift (subtle change)
Antigenic drift (dramatic change)
Neurons: Basic units of communication in nearly all nervous systems: Monitor information in and around the body and issue commands for responsive actions
Sensory neurons: (collect and relay info to spinal cord and brain)
Interneurons: (receive and process sensory input from the sensory neurons)
Motor neurons: (receive signals from interneurons to effect responses)
Neuroglia: A variety of cells that metabolically assist, structurally support, and protect the neurons
Pumping and Leaking: Movement is balanced outside vs. inside; movement itself, however, through active pumping of ions or leaking of ions, is essential to the formation of the action potential, to its propagation, and to its eventual silencing
Action potentials/â€œall or nothingâ€ responses: All action potentials are the same size
If stimulation is below threshold level, no action potential occurs
If it is above threshold level, cell is always depolarized to the same level
Once potential spikes, gated sodium channels close, potassium channels open
Influx of sodium stops, potassium flows out
Original voltage difference is reestablished
Chemical Synapses: Action potentials can trigger the release of neurotransmitters, signaling molecules that diffuse across chemical synapses
Gaps between the terminal ending of an axon and the input zone of another cell
Gaps can be between neurons or between a neuron and muscle or gland cell
Synaptic Transmission: Action potential in axon ending of presynaptic cell causes voltage-gated calcium channels to open
Flow of calcium into presynaptic cell causes release of neurotransmitter into synaptic cleft
Examples: acetylcholine, serotonin
Neuromodulators can magnify or impede the effect of a neurotransmitter
Neurotransmitter diffuses across cleft and binds to receptors on membrane of postsynaptic cell
Binding of neurotransmitter to receptors opens ion channels in the membrane of postsynaptic cell
Receiving cell can either be excited or inhibited
Signals must eventually be turned off
Information flow: Sensory nerves relay information to the spinal cord where they form chemical synapses with interneurons. Interneurons within the spinal cord and brain integrate signals; many snyapse with motor neurons to carry signals away from spinal cord and brain
Axons are insulated with a myelin sheath composed of Schwann cells; controls ion movement
Peripheral Nervous System Autonomic nerves: Visceral functions
Carry signals to and from internal organs and glands
Most organs are continually receiving both sympathetic and parasympathetic stimulation
Sympathetic nerves signal heart to speed up, and parasympathetic stimulate it to slow down
Which dominates depends on situation
Peripheral Nervous System Somatic nerves: Motor functions
Carry signals to and from skeletal muscle, tendons, and skin
Autonomic Nerves Sympathetic nerves: Originate in the thoracic and lumbar regions of the spinal cord; Ganglia are near the spinal cord
Promote responses that prepare the body for stress or physical activity (fight-or-flight response)
Autonomic Nerves Parasympathetic nerves: Originate in the brain and the sacral region of the spinal cord; Ganglia are in walls of organs
Promote housekeeping responses, such as digestion
Three Brain Divisions: Hindbrain
Midbrain
Forebrain
Hindbrain: Reflex control of vital tasks and complex reflexes, unconscious motor activity
Midbrain: coordinates reflex responses to sight and sounds
Forebrain: Cerebrum: coordinating sensory and motor functions, memory, abstract thought (olfactory bulbs deal with smell)
Thalamus: sensory signal coordination
Hypothalamus: controls homeostasis
Limbic system (body responses to emotion); Pituitary gland (growth, metabolism); Pineal gland (circadian rhythms)
Cerebrospinal Fluid: Surrounds the spinal cord and fills ventricles within the brain
Blood-brain barrier controls which solutes enter the cerebrospinal fluid
Important implications also for medical treatment of diseases and disorders
Anatomy of the Cerebrum: Largest and most complex part of human brain
Outer layer (cerebral cortex) is highly folded; a longitudinal fissure divides cerebrum into left and right hemispheres
Inside the hemispheres is the limbic system which controls emotions and plays a role in memory
Drugs and Addiction: A drug is a substance introduced into the body to provoke a specific physiological response
In addiction, a drug assumes an â€œessentialâ€ biochemical role in the body
Stimulants increase alertness and body activity, then cause depression
Caffeine, Nicotine, Cocaine, Amphetamines
Depressants and hypnotics lower activity of nerves and parts of the brain
Barbiturates, Alcohol, Morphine, Marijuana
Hormones: Secreted by endocrine glands, endocrine cells, and certain neurons
Travel through the bloodstream to nonadjacent target cells
Two main hormone types
Steroid hormones
Protein/Peptide hormones
Steroid Hormones: Derived from cholesterol
Estrogens, progestins, androgens (such as testosterone), cortisol, aldosterone
Most diffuse across the plasma membrane and bind to a receptor
Hormone-receptor complex acts in nucleus to inhibit or enhance transcription
Protein Hormones: Peptides, proteins, or glycoproteins
Glucagon, ADH, oxytocin, TRH, insulin, somatotropin, prolactin, FSH, LH, TSH
Hormone binds to a receptor at cell surface
Binding triggers a change in activity of enzymes inside the cell
Feedback Mechanisms: Negative feedback
An increase in concentration of a hormone triggers activities that inhibit further secretion
Positive feedback
An increase in concentration of a hormone triggers activities that stimulate further secretion
Glucose Metabolism: Hormones of the pancreas regulate the metabolism of glucose
Glucose Metabolism Glucagon: (alpha cells) raises blood glucose levels
Glucose Metabolism Insulin: (beta cells) lowers blood glucose levels
Glucose Metabolism Somatostatin: (delta cells) inactivates alpha and beta cells
Diabetes Mellitus: Disease in which excess glucose accumulates in blood, then urine
Symptoms include
Excessive urination
Constant thirst
Blurred vision
Unexplained weight loss
Unusual hunger
Unusual fatigue
Sores/wounds that do not heal
Two Types of Diabetes Type 1: Autoimmune disease triggered by environment or possible viral infection (beta cells destroyed)
Usually appears in childhood
Treated with insulin injections
Two Types of Diabetes Type 2: Target cells donâ€™t respond to insulin signals
Usually appears in adults
Treated with diet, drugs, insulin
Risk Factors for Type 2 Diabetes: Pre-Diabetes (impaired glucose tolerance)
Gestational diabetes
Obesity (overweight problematic)
People who are inactive
Age
Metabolic syndrome (high cholesterol, high triglycerides, low good â€˜HDLâ€™ and high bad â€˜LDLâ€™ and high blood pressure)
Some minorities are at higher risk
Possibly genetics
Gestational Diabetes: Pregnancy induced glucose intolerance that can lead to diabetes during the 3rd trimester
Risk factors for mother: being overweight prior to pregnancy, over-eating during pregnancy, pre-diabetes, family history of diabetes, previous delivery of large baby, ethnicity
Complications to fetus: birth defects, miscarriage, over-nutrition, excess growth, increased risk of developing diabetes later in life
Can be tested for and treated
Complications of diabetes: Heart disease and stroke (2-4X increased risk of death)
High blood pressure
Blindness (leading cause of blindness in adults)
Kidney disease (leading cause of end-stage renal disease)
Nervous system damage
Amputations
Dental disease
Complications of pregnancy
Coma
Lowered ability to fight off infections
Disease Management: Losing weight coupled with proper nutritional and eating habits
Nutritional intake must be closely monitored
Glucose levels must be monitored and adjusted
Exercise
Management of other diseases (cholesteral, high blood pressure, non-healing wounds)
Treatment with various drugs including insulin
Islet-Cell Transplantation: Beta cells from donor pancreas transferred into person with diabetes theoretically restoring proper insulin function
Benefits: reduces reliance on insulin injections, provides flexibility with nutritional intake, decreases chances of long-term complications from diabetes
Risks: rejection, side effects from immunosuppressive drugs (including cancer)
Success rate getting better, but only 400 patients world-wide have gotten the transplants with varying levels of disease regression
Only 17 US hospitals do the procedure
Type 1 diabetics currently only ones treated
Human Immunodeficiency Virus: RNA retrovirus that upon infection of human cells permanently integrates into the cellâ€™s genome
Enveloped virus with 2 major glycoproteins (gp120 and gp41)
Carries many enzymes with it to effectively infect new host cells
Replication of HIV: Initial infection occurs in cells of the immune system (macrophages and T cells), but over time HIV can gain access to other cell types as well, increasing disease symptomology
Acquired Immunodeficiency Syndrome: Combination of disorders that follows infection with HIV
In most individuals true symptoms of AIDS do not appear until 9-15 years after initial infection
Major disorders include:
Yeast (Candida) infections
Pneumocystis pneumonia
Karposiâ€™s sarcoma (cancer)
People generally die of infections or disorders, HIV itself does not directly kill
Transmission of HIV: HIV does not live long outside human body and so it is most often spread by exchange of bodily fluids with an infected person
In the U.S., anal intercourse and needle sharing are main modes of transmission
Becoming increasingly transmitted by vaginal intercourse and oral sex
Can travel from mothers to offspring during pregnancy, birth, or breast-feeding
Not known to be transmitted by food, air, water, casual contact, or insect bites
Effect of T-Cell Decline: CD4 helper T cells play a vital role in immune function
They are required for both cell-mediated and antibody-mediated immunity
Infected individual becomes vulnerable to other infections, which eventually result in death
Treatment regimens are geared towards both reducing the number of free HIV in the blood and to bolstering the immune system to fight back
Treatment Regimens: There is NO cure for HIV/AIDS
Once HIV genes are incorporated, no way to get them out; treatment will therefore be lifelong therapy
There is NO vaccine against HIV
HAART (Highly Active Anti-retroviral Therapy)
AZT, other replication inhibitors + protease inhibitors slow the course of the disease and increase life span if given in combination
Given as cocktails of a minimum of 3 anti-HIV drugs
Problems of severe side effects and drug resistance
Often given in context of other anti-microbial agents to prevent/treat opportunistic infections
LAK cells: lymphocytes are extracted from tumors and exposed to lymphokines; once activated the cells can be re-injected into a patient to fight tumors

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