Homeostasis Flashcards
What is the normal range for body temperature?
36.1-37.2 C
How can body temperature be measured?
- Rectal (gold standard)
- Tympanic membrane
- Axilla
- Oral
- Core sensors
- Skin patches
What is the definition of core temperature?
The temperature of structures deep within the body as opposed to peripheral temperatures such as that of the skin.
What temperature is considered hypothermia?
35 degrees Celsius
What temperature is considered pyrexia?
Over 38 degrees Celsius
How does the body generate heat?
ATP -> ADP and phosphate (exothermic reaction - oxidative phosphorylation)
- shivering
- non-shivering thermogenesis (brown adipose tissue)
- erector pill muscles contracting
- vasoconstriction
- hormonal thermogenesis from adrenaline and thyroxine
How does the body lose heat?
- sweating
- vasodilation
- erector pill relaxation
What are the regulatory mechanisms for controlling temperature?
What are the consequences of abnormal hypothermia?
- Sluggish thinking
- Reduced blood flow to tissues
- Confusion
- Increased urine production
- Hepatic dysfunction
- Paradoxical undressing
What are the consequences of abnormal hyperthermia?
- Sweating
- Rapid breathing
- Tachycardia
- Vasodilation
- Vomiting
- Headache
- Low BP
- Dizziness
- Syncope
- Oliguria
What are the therapeutic uses of hypothermia?
- Cardiac arrest survivors
- Head injuries
- Surgeries
- Encephalopathy
- Cardiopulmonary bypass
What are the therapeutic uses of hyperthermia?
Cancer treatment alongside chemotherapy and radiation
What are the health benefits of sleeping in a cooler bedroom?
- Deepened sleep faster
- Increased amount of brown fat
- Dispose of excess blood sugar - protects against diabetes
Why are testicles 2 degrees less than body temperature?
Sperm denatures quicker sperm would mutate more.
How does infection cause pyrexia?
Pyrogens. Can be either exogenous (microbial origin) or endogenous.
Exogenous
- LPS of gram negative bacteria
Endogenous
- released by activated macrophages
- IL-1, IL-6, TNF, interferon-alpha, gp130
What is a rigor?
An abrupt attack of shivering and a sensation of coldness, accompanied by a rapid rise in temperature. Marks the onset of a fever.
What causes a rigor?
- Bacterial infection
- Viral infection
- Childhood viruses
- measles, mumps, chickenpox, rotavirus
- Widespread skin infection
- Appendicitis
- Malaria
- Endocarditis
What is a febrile seizure?
Convulsion associated with high temperatures, normally in children. May not have underlying health problems.
How does the elderly brain often respond to pyrexia?
- Hypothalamus is less effective at responding to pyrogens
- Fever is absent in 20-30% of patients with an infection
- More prone to psychosis and brain damage
Why are ova bigger than spermatozoa?
- contains more genetic information
- rarer
- contains nutrients required for development
Where does iodine in our diet come from?
Fish and dairy products
Why might organic milk be a bad idea during pregnancy?
Iodine is important before, during and after pregnancy. More thyroid hormones need to be made during pregnancy to help foetal brain development.
Organic milk contains 35-40% less iodine than non organic milk.
What is a goitre?
Swelling of the neck from an enlarged thyroid gland.
What is the most common cause of a goitre globally?
Iodine deficiency
Which parts of the country have a high prevalence of goitres?
Countries that don’t used iodised salt (Australia and NZ)
What is Derbyshire Neck?
Goitre in people who resided in the English Midlands. Caused by lack of iodine in the soil.
What is prevalence?
Number or proportion of people who have a disease at a given point in time.
number of people with disease / total population = prevalence
What is incidence?
Number of new cases of disease within a given timeframe.
number of new cases / patient time at risk = incidence rate
Why aren’t monoclonal antibodies rejected by humans?
Monoclonal antibodies are usually ‘humanized’ to be administered to humans. The protein sequences are altered to be homogenous with human antibodies so they do not cause an immunogenic response.
What do patients dislike about MRI scanning?
- Claustrophobic
- Long time
- Stay still
- Delay in results
What needs to be maintained constant in the internal environment?
- Concentration of oxygen, carbon dioxide, salt and other electrolytes
- Concentration of nutrients, waste products
- pH of the internal environment
- Temperature of the internal environment
- Volume of pressure of body fluids compartments
What is homeostasis?
The physiological process by which the internal systems of the body are maintained at equilibrium, despite variations in the external conditions.
Homeo; same, stasis; state
What is a positive feedback loopback?
Output enhances the original stimulus.
What is a negative feedback loop?
Output reduces the original effect of the stimulus.
How is the human body powered?
Single cells convert chemical energy into electrical energy to produce an action potential. The body coordinates this to produce an action; muscle contraction, nerve impulses, action potential.
What are the single cell types of the body?
- Blood
- Spermatozoa
- Oocytes
What is a tissue?
A collection of cells specialised to perform a particular function. The cells may be the same type (nervous tissue) or of different types (connective tissue).
What is an organ?
A part of the body, composed of more than one tissue, that forms a structural unit responsible for a particular function.
What are the different body systems?
- Nervous
- Respiratory
- Cardiovascular
- Digestive
- Skeletal
- Muscular
- Reproductive
- Urinary
- Integumentory
- Endocrine
How do the body systems communicate with each other?
Nervous and endocrine system
What are the major endocrine organs?
- Pineal gland
- Hypothalamus
- Pituitary gland
- Thyroid gland
- Parathyroid glands
- dorsal aspect of thyroid gland
- Thymus
- Adrenal glands
- Pancreas
- Ovary
- Testis
How is the nervous system broken down?
- CNS
- spinal cord
- brain
- PNS
- sensory
- motor
- somatic
- autonomic nervous system
- sympathetic - fight or flight
- parasympathetic - rest and digest
