Pathophysiology Exam 1 (Homeostasis- Cardiopulmonary)

What’s homeostasis?

What’s homeostasis?

The body’s equilibrium point for normal, physiological function

-aka “basic physiological parameters that indicate an average, healthy individual”

Negative feedback

Deviation from homeostasis will cause the opposite effect of the original stimulus (Any change from the normal range is compensated by an action that reverses the initial change)

-Most common feedback loop in the body

Examples:

-Body temp (rise→ Sweating, vasodilation; Fall→ Vasoconstriction, shivering)

-Blood sugar (rise→ Insulin; Fall→ Glucagon)

Positive feedback

Response enhances or amplifies the changes

-Least common in the body

Examples:

-Contractions (continual release of Oxytocin enhances strength of contraction until baby is delivered)

-Coagulation (clotting factors will keep being released until bleeding is stopped)

Why do variations in normal values exist?

Variations within normal physiological values exist due to a variety of reasons such as genetics, age and sex.

-Females typically have a lower hemocrit and slower metabolism than men.

Activity and environmental factors can also result in variations from normal values.

-Due to the efficiency of their heart function, most athletes have a lower heart rate when compared to the general populace.

Examples of homeostasis in the body

-Blood pH around 7.35-7.45

-Heart beats around 75 bpm

-average body temp 37 degrees C

-15-20 breaths/minute

Cause vs effect

Cause refers to something which gives rise to an action or condition

Example:

-Anemia (a condition involving a lower # of healthy RBC) results in higher levels of EPO (a cytokine which promotes RBC production).

Effect refers to a change which is a result or consequence of a cause

Example:

-Elevated EPO is an effect of Anemia

What causes disease?

Disease occurs when normal homeostatic mechanisms fail to return the body back to “normal”.

-Disease occurs to a variety of reasons such as pathogens, nutrition, genetics and trauma

Relationship between pathogens and disease

A pathogen is an organism which causes disease (includes bacteria, viruses, animals, parasites, ect)

-Pathogens cause create illness by destroying tissue, releasing toxins, stealing nutrients, and causing metabolic shifts.

Environmental changes have begun to impact the disease patterns

-Diseases commonly associated with certain environments have been found in areas previously unaccustomed to them (ex. tropical diseases malaria and dengue fever have reported in areas of the US such as MN)

-Emerging and re-emerging diseases have also become an issue (includes zoonoses diseases such as Zika, Hendra, SARS 1, ect and old diseases such as measles TB)

-Travel has also impacted disease patterns by introducing diseases into new areas

Importance of immunological memory

Immunological memory is the ability of the immune system to respond more rapidly and effectively to pathogens that have been encountered previously

-Essential helps the body to be better equipped to fight certain disease upon re-exposure.

-Reason why emerging/re-emerging and unfamiliar diseases are such a problem as the body is not equipped to fight against them due to less effective immune response

Zoonoses

a disease which can be transmitted to humans from animals.

Can the immune system have negative impacts the body?

Yes, the immune system can have negative impacts of the body.

-This can be due to the tissues/cells being targeted by the immune system or an overactive response

-In some forms of HIV, phagocytic immune cells will attempt to remove the pathogen through destroying brain tissue.

Relationship between nutrition and disease

Nutrition is important as it provides the body with necessary substances for physiological functioning.

-Too much or too little of any nutrients can create problems

Examples:

-excessive Na+ can cause high blood pressure; low Na+ can cause heart arrhythmias due to interference with the heart’s electrical signal

-Low vitamin C can cause scurvy

degenerative conditions

A disorder characterized by the progressive loss of function and/or structure of the affected tissues.

Examples:

-Arthritis

-Osteoporosis

-hearing loss

Relationship between genetics and disease

Genetics play a role in disease due to inherited conditions and susceptibility or resistance to developing diseases

Examples:

-Persistent cases of measles in Europe resulted in a selection pressure favoring mutations against the disease → Inheritance of those gene helped protect future generations against measles

-Similar to malaria and sickle cell anemia (The protection sickle cell anemia offered against malaria resulted in a selection pressure for the disease)

Epigenetics

the study of how your behaviors and environment can cause changes that affect the way your genes work.

-Changes are reversible and don’t affect DNA sequence (impacts gene expression)

Relationship between trauma and disease

Trauma produces disease by interfering with the functioning of organs.

Examples:

-Interruption to blood supply deprive tissues of nutrients and impact

-damage to blood vessels can lower blood pressure

-Burns to the integument can decrease the body’s ability to regulate its own temp

Iatrogenic diseases

Conditions caused by medical interventions or personnel

-Includes things such as giving wring medication, improper asepsis technique, nosocomial infections, ect

Predisposing factors

a variable associated with an increased risk of disease or infection.

Examples:

-Tissue damage caused by third degree burns increases the chances of an individual developing infections and electrolyte imbalances

-Poor nutrition can increase risk of cardiovascular diseases or type II diabetes

-Inheritance of mutated genes can increase the risk of certain cancers

What’s cancer?

A disease in which abnormal cells divide uncontrollably and destroy body tissue.

-Term groups together numerous conditions

Characteristics of cancer

-uncontrolled cell reproduction

-Undifferentiated cells (cells that have not yet developed into a specific cell variety)

-Abnormal function due to genetic mutation

*Genetic alternations in the cell inhibit apoptosis

Apoptosis

Mechanism used for destroying abnormal cells through cell death

-In cancer, apoptosis is inhibited

Angiogenesis

Formation of new blood vessels through the migration, growth and differentiation of endothelial cells

-tumors can secrete angiogenesis factors to increase blood supply to themselves→ Helps in growth through nutrient delivery of essential substances and waste removal

anaplasia

the loss of the mature or specialized features of a cell or tissue (cells regress and undifferentiate)

-Undifferentiated cells can’t carry out normal functions (especially those pertaining to normal metabolic functions→ mitotic rate increases resulting in structural abnormalities like enlarged nuclei, mitochondrial damage, and cytoskeleton damage

-Surface markers can also be altered, allowing abnormal cells to migrate and avoid detection via the immune system

metastasize

Ability to spread from an initial or primary site to a different or secondary site within the host's body

-Characteristic of malignant cells

Cell cycle

1.) G1 (first gap phase): the cell increases in size and prepares to replicate its DNA.

2.) S Phase (synthesis phase): The cell replicates its DNA. At the end of this phase, the cell has two complete sets of chromosomes

3.) G2 phase (Second Gap Phase): The cell continues to grow and prepares for division.

4.)M phase (Mitosis): the cell stops growing and divides into two daughter cells, each with the same number of chromosomes.

*G1-G2 are called interphase

*After G1, cells can exit the cycle and go into G0 when it receives a signal to differentiate, or when resources are insufficient to grow and divide

Mechanisms which destroy abnormal cells

There are various checkpoints throughout each phase of the cell cycle which regulate whether a cell can enter a new stage (these proteins can instruct cells to differentiate, divide or initiate cell death)

-Made up of both stimulating and inhibiting proteins

-Certain conditions have to be met before a cell can progress to the next phase

What determines the type of cancer?

Cancers are identified by the type of tissues they originate from

Examples:

-Carcinoma: tumors originating from epithelial cells (skin, digestive lining, ect)

-Sarcomas: tumors Originating from connective tissues (typically include several names as connective tissues types vary dramatically)

-Lymphoma: Cancer of lymphatic system

-Glioma: occurs when the glial cells of the nervous system become cancerous

Genetics and cancer

Many types of cancer arise from gene mutations

-Some tumors have been linked to mutations on p53 gene (codes for apoptosis) and tumor suppressor genes.

-Having a mutation does not guarantee the development (same with not having a mutation)

Viral infections and cancer

Some viral infections have been associated with increased risk of certain cancers (its been theorized viral genes act as tumor promoters if they insert in specific locations)

-HPV is an identified risk of cervical, anal, throat and penile cancers

-Hepatitis B is a promoter of Liver cancer

carcinogenic chemicals and cancer

Numerous chemicals have been demonstrated as mutagens, chemicals which cause mutations in the DNA.

-These mutations can alter cells functionality or cause the cell to become cancerous.

Examples:

-Aflatoxin, a family of toxics produced by certain molds, can cause liver cancer

environmental factors and cancer

Many different environmental factors can trigger the development of certain cancers

-Ultraviolet rays can damage DNA in skin cells, resulting in the development of skin cancers

-Many pollutants (both naturally occurring and synthetic) are carcinogenic

how is cancer diagnosed?

Cancer is typically diagnosed through a combination of physical symptoms (fatigue, anemia, cachexia, ect) and diagnostic techniques

-Diagnostic techniques (pap smears, X-rays, ultrasounds, tumor antigens, ect) have aided in the early identification of cancer

Cancer treatments

Three Primary treatment methods of cancer:

1.) Surgery: surgical removal of tumor (best with non-metastasized cancers)

2.) Chemotherapy: use of chemicals which interfere with tumor growth

3.) Radiation: causes damage to dividing cells and may trigger apoptosis through beam of intense energy

Newer techniques include:

-Antiangiogenetic compounds: substances that can block the growth of new blood vessels to tumor

-Monoclonal antibodies and other immunostimulants such as interferon: enhance immune response against cancer cells

Gene therapies: can repair the damage to the DNA

*Not all cancers require treatment; Some tumors pose little risk to health and treatments (in some cases) can cause more harm than good

physiological functioning of stress

Any environmental or physical pressure that elicits a response from an organism.

Can have numerous impacts on the body such as:

-activation of the sympathetic nervous system (fight or flight response)

-increased adrenalin secretion

-increased cortisol levels increased LDL levels

-Increased storage of abdominal fat

While some of these impacts can offer short term benefits, continual basis of them can be harmful (ex. Chronic stress is associated with weight gain, heart disease, cancer, diabetes, autoimmune conditions, asthma, and depression)

Relationship between muscular and nervous system

Sodium vs Potassium abundance

-Sodium is the most abundant extracellular cation

-Potassium is the most abundant intracellular cation

Resting Membrane potential

The theoretical voltage due to the difference in the ion concentrations between the inside of the cell membrane and the outside.

-Normally between 65 mV and -85 mV

-The outer surface of the cell is negative due to negatively charged proteins

-The outside surface of the cell is positive due to potassium

Action Potentials

A rapid sequence of changes in the voltage across a membrane.

-Occur when ion gates on the membrane surface open and allow ions to flow down the concentration gradient. 

-An action potential will only be triggered if charges cross a specific threshold level (crossing reverses the charges and allows continuation of the impulse)

-Action potentials can be triggered through physical/sensory receptor stimulation or neurotransmitters

Depolarization

A change resulting in less negative charge inside the cell compared to the outside (cell becomes more positive)

-Caused by the intracellular intake of Na+ ions via sodium channels

Repolarization

the change in membrane potential that returns it to a negative value (Positive→ negative)

-Caused by loss of potassium outside of cell through the opening of potassium channels

Hyperpolarization

a change in a cell's membrane potential that makes it more negative.

-moves RMP further from the threshold level→ makes it harder to reach the threshold and stimulate nerves/ muscle

-Hypokalemia (low K+) can cause hyperpolarization

Hypopolarization

a change in the membrane potential that makes the membrane less negative inside

-RMP moves closer to the threshold level→ action potentials are easier to trigger

-Adrenaline and caffeine can hypopolarize membranes, resulting in muscle twitches

Common symptoms associated with neuromuscular problems

Both physical and functional changes are used for early identification of neuromuscular problems

Includes:

-Headache

-Changes in personality and level of consciousness

-Paresthesia

-Changes in muscle function and reflexes

-Changes in language

Headaches

A painful sensation in any part of the head

-Pain can range from mild to severe

-Can indicate a variety of conditions such as low blood sugar to strokes (headaches with other neurological symptoms should be further investigated)

-Common types of headaches include: Tension headaches, Visual headaches and migraines

Tension headaches

usually characterized by diffuse and constant pain and tight neck and shoulder muscles. 

-Can indicate poor posture, stress or conditions which limit muscle movements.

Visual headaches

Characterized by pain around the eyes (usually a result of intra and extraocular muscles trying to focus)

-Gain intensity as over time

-Associated with need for corrective lenses or strenuous activities such as reading/looking at computer screen for prolonged periods of time

-Common among students and office workers

Migraines

Characterized by localized pain, usually described as throbbing

-often associated with spasming blood vessels and localized inflammation

-Other characteristics include nausea, vomiting, visual disruptions and extreme sensitivity of light

-Migraines can be associated with specific triggers such as smoking, food additives, ect

-also often proceeded by an aura (a sensory disturbance such as unusual tastes, wavy lines or halo vision, or tunnel vision)(Similar to a warning sign)

Delirium

Serious disturbance in mental abilities that results in confused thinking and reduced awareness of surroundings.

-Usually involves disorientation, restlessness, hallucinations and agitation

-Can occur with a high fever

Dementia

A decline in mental function resulting in personality changes, language usage, memory, and spatial orientation. 

Somnolence

A state of drowsiness or strong desire to fall asleep

-Individual can still respond to disturbances (but will quickly fall back asleep)

Chronic vegetative state vs coma

A chronic state of brain dysfunction in which a person shows no signs of awareness.

-usually occurs with severe damage to the brain

-Brain scans show no activity in the cortex.

-Individual may appear awake, but does not respond to stimuli (may still make noise, have their eye’s open or move)

*Coma refers to the state in which a person appears to be asleep but cannot be awakened

Glasgow coma scale

Scale used to evaluate patients on their level of consciousness

-based on a set of criteria involving motor and verbal responses which correspond to a point system

-Typically 8 or fewer indicates comatose.

Paresthesia

Sensations of numbness, tingling or excessive sensitivity( described as “Pins and Needles”)

-Can indicate severe damage or temporary issues

-Examples include phantom pain in amputated limb, pinching ulnar nerve, Hanson’s disease, ect

Dermatome Map

Map used to identify the specific regions covered by each of the spinal nerve

-Can help detect and diagnose conditions or problems affecting your spine, spinal cord or spinal nerves.

Changes in muscle function and reflexes

Changes in muscle function and reflex responses may indicate neurological problems or muscular problems (spinal injuries, damage to synaptic junctions, interruption between nervous and muscular connection, ect)

Types Include:

-Hyporeflexia: Normal but weak reflexes

-Hyperreflexia: exaggerated reflex

-Areflexia: A total lack of reflex response

Changes on language

Damage to Wernicke’s area (language understanding) and Broca’s area (ability to speak) can result in changes to language

-Aphasia: loss of ability to communicate (It may involve problems with expressing oneself or with interpreting the input)

-Global Aphasia: loss of receptive and expressive language (can’t express themselves or interpret input)

-Spastic dysphonia: A condition where vocal cords spasm due to inflammation and lowered activation energies at the level of the cords (impacts vocal and speech ability)

Physical damage to nervous system

Any physical damage to the nervous system can disrupt function

-Damage to membrane can impact membrane potentials and integrity, causing or preventing impulses

-disruption of blood flow can alter membrane potentials

-Damage to glial cells can interfere with normal transmission of action potentials

-formation of scar tissue in PNS or CNS can interfere with regrowth of nerves and interfere with transmissions (scar tissue is a poor conductor)

Traumatic brain injury

physical injury to the brain causing an alternation or disruption of normal brain function.

-Can be caused by shaking, falls, being hit, or a penetrating injury.

-Concussions, blunt force trauma, and penetrating injuries are all categorized as types of TBIs

Concussion

A type of TBI caused by head injuries (bump, falling, blows, shaking, ect)

-Common symptoms include headache, confusion, blurred vision, nausea and vomiting, memory loss, unequal pupils, and loss of consciousness

-Can be mild (not typically associated with permanent damage) or severe (can cause strokes, hematomas and even death)

Hematomas (intracranial hematomas)

Bleeding into the brain or the meninges produces

-creates a pool of blood that exerts pressure on the brain (raises intracranial pressure)

-Rate of bleeding can impact what/when symptoms occur

-As intracranial pressure increase, symptoms such as headaches, unequal pupils, memory loss, muscle weakness, gradual personality changes and progressive loss of consciousness can occur (Slower bleeding may result in coma after awhile)

-Things which can cause hematomas include: vessel tears from direct impact of brain against skull injuries, hypertension, anticoagulant therapies and chronic alcoholism

Stroke (Cerebrovascular accidents)

Occur when blood flow is disrupted to a section of the brain. 

-Typical symptoms include unilateral paralysis, loss of consciousness, severe headache, aphasia, loss of balance, and unequal pupils (F.A.S.T.)

-Deprivation of oxygen supply results in the death of nervous tissue (>10 minutes can cause irreversible damage)

Two Major types:

-Ischemic strokes: Caused by blockage (clots or emboli) of a blood vessel

-Hemorrhagic stroke: caused by bleeding due to a tear or aneurysm

Treatments include streptokinase (clot bursting drug or surgery)

*Transient ischemia attacks (TIA’s) are often referred to as mini strokes as symptoms are of limited duration, usually minutes to hours. 

Intracranial pressure

Refers to pressure inside your skull

-due to the immovability of the skull, increased intracranial pressure (ICP) can have devastating effects of the brain/other tissues

-Symptoms/signs include respiratory dysrhythmias (abnormal breathing patterns), blood pressure fluctuations (high systolic, bradycardia, widening pulse pressure), hydrocephalus and vasodilation due to lowered oxygen and pH levels, and increased CO2

-ICP can occur from trauma, hematoma, disruptions of vascular permeability, tumors, infections and excess cerebrospinal fluid (CFS). 

Spinal cord injury

Damage to any part of the spinal cord or nerves at the end of the spinal canal

-Symptoms of spinal injuries depend on the location of the damage (ex. damage at C2 can produce total tetraplegia and respiratory paralysis while T2 causes leg paralysis)

-Initials symptoms present as spinal shock (altered physiologic state immediately after a spinal cord injury; Inflammation and loss of membrane integrity alters motor and sensory activity)

Types of Spinal Cord Injuries:

-Spinal compression: Occurs when the cord is pinched or crushed (ex. Herniated Disc)

-Spinal laceration: Occurs when the cord is torn (bleeding can cause spinal stroke)

-Spinal transaction: a complete severing of the cord.   

Chiara malformation

Structural defect where brain tissue (portion of brain stem and cerebellum) extends into the spinal canal through the foramen magnum

-Movement of the neck can pinch brain tissue and interfere with CSF flow.

-Symptoms include neck pain, muscle numbness and tingling, headache, difficulty breathing or swallowing, loss of motor coordination, and balance issues. 

*This condition predisposes the brain stem to trauma

Neurological infections

Bacteria, parasites, and viruses can disrupt function in the nervous system through:

-Inflammation (increases intracranial pressure, crush neurons, disrupt membranes, ect)

-Fever (tremors, seizures, denature proteins, hallucinations, ect)

-Toxins (physical destruction of nerves, block neurotransmitters, cause clots, alter membrane potentials, rupture blood vessels, ect)

Meningitis

an inflammation of the meninges (usually the pia mater and arachnoid membrane of the brain/ spinal cord)

-Can be caused by viruses (mumps, herpes, ect), bacteria (Neisseria menigitidis, Streptococcus ssp, ect), fungi, parasites or toxins

-Inflammatory response causes swelling and increased pressure

-Symptoms include headache, fever, nuchal rigidity(neck stiffness), positive Brudzinski’s sign (neck flexion causes reflex flexion in hips and knees)

-Progression of infection can cause septic emboli (leading to strokes, gangrene, seizures, ect), depression of CNS functions and loss of consciousness.

Encephalitis

inflammation of the brain

-Infection can be viral or bacterial Usually caused by viral infections resulting from ticks or mosquitoes; Chronic lead poisoning can also be a cause)

-Destruction of infected neurons & demyelination of white matter in the brain damages the CNS

-Symptoms include restlessness, headache, fever, cerebral edema, mental deterioration leading to coma, personality changes, seizures, vomiting, and pupil irregularities.

Rabies

A deadly virus spread to people from the saliva of infected animals (cats, dogs, bats, raccoons, skunks and rats)

-Once inside the body, the virus travels along the peripheral nerves to the CNS destroying cells

-Symptoms include fever, headache, muscle pain, and nausea. 

Two Major Forms:

1.) Furious Rabies: inability to swallow, hallucinations, and extreme excitability.

2.) Dumb Rabies: Quite, lucid, progresses rapidly to coma and death.

Tetanus

An infection caused by the bacteria Clostridium tetani, a common soil organism

-Once in the body, the organism produces a toxin which mimics neurotransmitter functions causing muscles spasms, pain, and spasmodic paralysis (especially in neck and lower jaw)

-Also referred to as “lockjaw”

Botulism

A rare poisoning caused by toxins produced by Clostridium botulinum bacteria

-Toxin prevents muscle stimulation by blocking acetylcholine receptors at the myoneural junction

-Symptoms include nausea, blurred vision, difficulty swallowing, muscle weakness and flaccid paralysis develops.

Polio

An infectious disease caused by a poliovirus

-typically transmitted through contaminated water or an oral fecal route. 

-Once in the body, the virus multiplies in the somatic motor neurons (innervates skeletal muscle), killing them

-Symptoms include fever, fatigue, headache, vomiting, stiffness of the neck and pain in the limbs, paralysis

-Post polio syndrome: redevelopment of neurological symptoms after the initial infection (30 or more years)

West Nile virus

A mosquito-borne disease originating from Africa (normally found in birds but can be transmitted by mosquitoes)

-Most people infected by virus are asymptomatic

-However, in the elderly and people with compromised immune systems, the virus can cause meningitis or encephalitis. 

-First US case documented in 1999

Zika

Zika virus is a mosquito-borne virus originally identified in Africa during the 1940s

-Associated with birth defects such as microcephaly in newborns (other severe brain damage can also occur)

-Also linked to cases of Guillain-Barré syndrome (A condition in which the immune system attacks the nerves)

-Zika virus can be sexually transmitted

PTSD

A psychiatric disorder that may occur in people who have experienced or witnessed a traumatic event

-Individuals with PTSD tend to have an overactive amygdala (body’s alarm system) and underactive prefrontal cortex (regulates thoughts, actions and emotions)→combination contributes to heightened fear response of people with PTSD

-hippocampus (memory center) may also be a contributing factor

Seizure Disorders

Epileptic seizures are characterized by abnormal electrical activity in the brain.

-Some forms of seizures can be related to genetic conditions, head trauma, infections, strokes, medications, toxins, ect

Different types:

-Grand mal seizures: involve spasms of the major muscle groups and loss of consciousness

-Petit mal/ absent seizures: result in only a momentary loss of consciousness

Status Epilepticus

Occurs when a seizure lasts more than 5 minutes or when seizures occur very close together and the person doesn't recover consciousness between them.

Parkinson’s disease

Caused by the reduction of dopamine in the brain due to death of cells in the substantia nigra (structure located in midbrain which participates in movement control and rewards)

-Has been linked to head trauma, genetics, certain medications, and exposure to certain pesticides

-The condition usually develops slowly with symptoms becoming increasingly worse over time

-Symptoms include resting tremors, voice tremors, bradykinesia (slow movement), rigid muscles, and problems with balance (dementia can also occur in the later stages)

Essential tremor

A nervous system disorder that causes rhythmic shaking

-Tremors typically appear in the hands (can also affect head, legs, voice, and arms)

-Often mistaken for Parkinson’s disease

Multiple sclerosis

MS is a demyelination disorder where plaques form in the myelin, resulting in the infiltration of scar tissue in the sheath.

-Exact etiology is unknown (although its been theorized viral infections and autoimmune conditions may be a contributing factor)

-symptoms include visual disruptions, blindness, weakness, muscle spasms and paralysis

Amyotropic lateral sclerosis

ALS is a demyelination disease characterized by the degeneration of motor neurons of the cerebral cortex, brain stem, and spinal cord (decrease of neurons leads to muscle weakness and atrophy)

-More common in men with initial symptoms appearing in their 40-50s

-Symptoms include muscle weakness, slurred speech and difficulty swallowing

-Death usually occurs 3 to5 years after diagnosis. 

-No known cause or treatment

Myashenia gravis

Myasthenia gravis is an autoimmune condition characterized by the production of antibodies which bind to the acetylcholine receptors at the myoneural junction (prevents transmission of nerve impulses to target muscle)

-Common symptoms include loss of facial expression, droopy eyelids, muscle weakness (upper extremities→ full body) and fatigue

-Can led to respiratory failure (condition known as Myasthenic Crisis)

Rhabdomyolysis

Rhabdomyolysis is a breakdown of muscle (can be due to direct or indirect muscle injury)

-iron-based myoglobin proteins released from damaged muscle membranes can leak into the blood and prevent filtration by the bowman’s capsule→ kidney failure (called free myoglobin)

-Symptoms include edema, weakness, and fatigue (cardiac dysrhythmias can also occur due to electrolyte imbalances)

Muscular dystrophy

A broad category of related genetic conditions which result in degeneration of skeletal muscles

-Caused by malformation of dystrophin, a cell membrane proteins which helps stabilize and protect muscle fibers (results in cell death and a loss of muscle function)

-Age of onset, rate of disease progression and primary muscles affected determine type of muscular dystrophy

Fibromyalgia

A condition which causes chronic muscular pain and stiffness (usually widespread)

-More common in women

-Aggravated by stress and fatigue

-Unknown cause (Should be noted people with fibromyalgia show increased sensitivity to prostaglandin P, a neurotransmitter associated with pain sensations)

Hormones

chemical messengers secreted by endocrine glands (ductless glands) into the blood stream

-Most hormones are either Lipid-soluble (mostly steroids) or non-lipid soluble (protein or amino acid based)

-Non-lipid soluble proteins cannot easily pass through plasma membrane, meaning they have to rely on second messengers or binding to exterior receptors to alter function of target cell (Lipid soluble can easily pass through cell membrane and bind to DNA/internal receptors)

-Composition impacts how delivery method of therapeutic hormones (Steriod-based hormones can be given via cream/transdermal patch, protein hormones through through injections and amino acid hormones can be taken orally)

-Production, release and clearance impacts blood hormone levels

Endocrine hypofunction

Occurs when the endocrine response is inadequate to correct the homeostatic abnormality

Two causes of hypofunction:

1.)Hyposecretion: The amount of hormone secreted falls below what is normal for the level of stimulation or releasing hormone (can occur with lack of precursors, agenesis (lack of structural development) or atrophy

2.)Hormone resistance: Target cell does not respond to secreted hormone

Endocrine hyperfunction

occurs when the endocrine gland secretes too much hormone (hypersecretion) and the levels of hormone in circulation are inappropriately high. 

-Can be cause be autoantibodies (can mimic releasing hormones, causing elevated hormone levels not regulated by negative feedback), tumors (can lead to hypersecretion/ overexaggerated response

Pancreas

The pancreas has both exocrine and endocrine functions

-Pancreatic acinar cells (The acini) secrete digestive enzymes and buffers into pancreatic duct to be later dumped into the duodenum

-The islets of Langerhans control endocrine functions and are composed of three types of cells: Alpha cells, beta cells (most common) and delta cells

Glucagon

Hormone which raises blood sugar through breakdown of glycogen (glycogenolysis)

Insulin

Hormone which lowers blood sugar by moving glucose and amino acids into cells

-Also promotes Glycogenesis

Somatostatin

Hormone which suppresses both insulin and glucagon secretions

Glycogenesis

the formation of glycogen when glucose levels of high

Glycogenolysis

the breakdown of glycogen

Gluconeogenesis

the formation of glucose from non-carbohydrate sources (ex. actate, amino acids, and glycerol)

Lipolysis 

the breakdown of lipids to produce energy and metabolites. 

Lipogenesis

the creation of lipids from excess sugars or amino acids. 

Diabetes Mellitus

A metabolic disorder characterized by higher than normal plasma glucose levels. 

-Can result in changes to blood vessels and nerves due to glycation of proteins (attachment of sugar to protein)

-glycation of proteins can cause microangiopathy (small vessel problems), slow wound healing/infection are common, diabetic nephropathy (deterioration of kidney function) and peripheral neuropathy

-Atherosclerosis (thickening of blood vessels) + increased platelet binding and LDLs due to glycated collagen raises risk of strokes and heart attacks

Type 1 diabetes

A type of diabetes that occurs when beta cells stop producing insulin (why its called insulin dependent diabetes)

-Strong genetic component (interaction of genetic factors via medication, viral infections or chemical agents can cause the production of antigens which attack b cells)

-Lack of insulin lead to hyperglycemia, polyuria, ketoacidosis and diabetic coma

Type 2 diabetes

A type of diabetes that occurs due to insulin resistance in cells

-Usually caused by genetic factors in combination of poor diet/inadequate amounts of exercise

-Insulin levels may be elevated due to normal, homeostatic mechanisms

-Typically has a slower onset than diabetes type 1

Gestational diabetes

Occurs when the pregnancy hormone placental lactogen (prepares for breast feeding) causes a rise in blood glucose levels greater than the woman’s body can handle

-High blood sugar levels can cause excessive fetal growth, resulting in delivery complication