Unit 5 - Homeostasis Flashcards
steady state of being in organisms
homeostasis
optimal body temp
37 degrees
optimal blood sugar
4 mmol/L
optimal blood pH
7.35
All homeostatic control systems have three functional components:
A receptor (or monitor) A coordinating centre A regulator (or effector)
what do all homeostatic control systems start and end with
stimulus and response
conscious responses
behavioural response
unconscious responses
physiological responses
Negative feedback systems
(also called negative feedback loops) are mechanisms that make adjustments to bring the systems of the body back to within an acceptable range. The system reacts to stimulus by doing the opposing action (i.e. when the body gets too hot the system cools it by sweating).
Positive feedback system
A positive feedback system is the opposite of a negative feedback system. It reinforces small changes to make them larger or amplified. Positive feedback moves the target variable even further away from its steady state or increases the magnitude of the change away from the steady state resulting in a change in the body’s status, rather than a return to homeostasis.
thermoregulation
maintenance of body temperature within a range that enables cells to function efficiently
ectotherms
organisms with metabolic rates are dependent on external temperatures and other external elements. Invertebrates, as well as most fish, amphibians, and reptiles, are ectotherms.
endotherms
organisms able to maintain a constant internal body temperature, regardless of their surroundings. They have evolved metabolic processes that generate internal heat from organs such as the kidney and liver. As a consequence, they are less vulnerable to changes in external temperatures.
“thermostat” for thermoregulation is located in
hypothalamus
excretory system has three main jobs:
to remove waste
monitor water balance
control pH
Main organs of the excretory system
kidneys (remove metqbolic waste, maintain blood chemistry + water levels)
liver (transforms ingested toxins into soluble compounds that can be eliminated in kidneys, or create metabolites which are hazardous products of protein metabolism)
large Intestine (removes toxic waste from digestive system)
There are two types of waste produced by the human body:
Digestive waste
Cellular waste (byproducts of cell respiration e.g. carbon dioxide and nitrogenous waste)
nitrogenous waste + 3 types
cellular waste based in nitrogen (typically proteins)
Ammonia
Urea
Uric acid
Ammonia waste
- a water-soluble toxic gas.
- type of waste that is a by-product of protein digestion.
- amino group is removed through a process called deamination.
Deamination
occurs in the liver of humans. The by-product of deamination is ammonia
Urea
two molecules of ammonia combined with co2, is created to detoxify ammonia in the body
uric acid
waste product created through breakdown of nucleic acids
human urinary system
- most important waste-removal system in your body
- removes waste from blood, and balances levels
what tubes empty urine into the bladder
ureters
on average how much can a bladder hold and at what volume does it typically signal to eliminate
- 600ml
- signalled between 200-400mL
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name parts of kidney and identify where nephrons would be
located in the cortex and extend into the medulla, surrounded by capillaries
Each nephron consists of five main parts:
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Bowman’s capsule (containing the glomerulus)
Proximal tubule
Loop of Henle
Distal tubule
Collecting duct
afferent arteriole
blood in
efferent arteriole
blood out
artery vs vein
Arteries carry blood away from the heart, and veins carry blood towards the heart. With the exception of pulmonary blood vessels, arteries carry oxygenated blood and veins carry deoxygenated blood.
path of blood flow in nephron
- afferent arteriole brings blood to nephron
- blood branches into glomerulus (capillary bed) which is enclosed in bowman’s capsule
- fluid from blood is squeezed into the capsule
- filtered blood leaves via efferent arterioles which branches into pertibular capillaries which will reabsorb the non waste that is filtered out from the blood during urine formation
3 steps in urine filtraion
- Filtration (in glomerulus and bowmans capsule - fluid is filtered out blood in glomerus and flows into the bowmans capsule)
- Reabsorption (in proximal tube, filtrate from b capsule are selctively reabsorbed via active/passive transport, descending side of loop of Henle water is lost through osmosis, and ascending loop of henle the Na+ is actively tansported into the medulla)
- Secretion (starts in distal tube where H+, Na+, K+ are selectively reabsorbed into nephron via active transport, water is removed which regulates concentration of pH and electrolytes. The remainder is urine which moves to collecting duct to be secreted into the bladder)
substances transported in 1st step of urine filtration
Na+, Cl-, water, H+, glucose, amino acids, vitamins, minerals, urea, uric acid via pressure
substances transported in 2nd step of urine filtration
Water at descending side of loop of Henle through osmosis, and NaCl at ascending loop of Henle via active transport
substances transported in 3rd step of urine filtration
Water, Salt, Urea, Uric Acids, K+, bicarbonate, H+
what to systems are required for the urinary system to maintain homeostatis and why
endocrine and nervous, nerves will pick up signals to activate hormones that activate negative feedback systems used to maintain balance
Antidiuretic hormone (ADH),
helps to regulate the osmotic pressure of body fluids by causing the kidneys to increase water reabsorption. ADH moves along specialized fibres from the hypothalamus to a gland called the pituitary gland, which stores and releases ADH into the blood.
osmoreceptors
specialized nerve receptors in the hypothalamus that picks up changes in osmotic pressure in the blood
acts on the nephrons to increase Na+ reabsorption
aldosterone
Aldosterone is produced in
the cortex of the adrenal glands
Describe how the bicarbonate buffer helps the kidneys to regulate blood pH through negative feedback when pH is too high
The carbonate ion bonds to any excess H+ ions to form carbonic acid ( H2CO3 ) and so lowers the blood pH.
The carbonic acid breaks down into carbon dioxide and water, and the CO2 is transported to the lungs, where much of it is exhaled.
Describe how the bicarbonate buffer helps the kidneys to regulate blood pH through negative feedback when pH is too low
The carbonic acid breaks down into H+ ions and water, in order to raise the blood pH.
what test is conducted to detect kidney disorders
urinalysis
Diabetes insipidus
occurs when the ADH-producing cells of the hypothalamus, or the nerve tracts leading from the hypothalamus to the pituitary gland, are destroyed. Without ADH to regulate water reabsorption, urine output increases considerably, so none of the remaining 15% (after the other 85% has been reabsorbed at the proximal tubule), is recovered. As much as 20 L of dilute urine may result, creating a strong thirst response, and a severe need to replace lost water.
Urology Glomerulonephritis
This disease is also known as nephritis or the inflammation (swelling) of the nephrons. one type of nephritis affects the tiny blood vessels of the glomerulus. Toxins produced by invading microbes destroy the tiny blood vessels, altering the permeability of the nephron. This means that proteins and other large molecules are able to pass into the nephron. When the nephrons are destroyed, no mechanism occurs in the nephron membrane to reabsorb protein; instead, the protein remains in the nephron and draws water from the neighbouring peritubular capillaries, which, in turn, increases the output of urine.
diabetes mellitus
When a deficiency of insulin occurs because of a defect in the pancreas, blood sugar levels tend to rise. The cells of the proximal tubule are supplied with enough ATP to reabsorb 0.1% of blood sugar. When higher blood sugar concentrations exist, such as in a person with diabetes, the excess sugar remains in the nephron. This excess sugar in the nephron draws water into the nephron, increasing the volume of urine. Individuals with diabetes mellitus expel large volumes of urine, which explains why they are often thirsty and have to replace the lost water.
UTI
If bacteria accumulates in the urethra it may cause an infection in the bladder. Once it is in the urinary tract, the infection may cause an immune response which may include increased white blood cells and/or fever. If the infection spreads upwards through the ureter into the kidney, there can be more severe health complications such as kidney failure or the bacteria entering the bloodstream (a condition known as sepsis).
Kidney stones
occur when solutes from the blood precipitate (solidify) out of the urine. These solutes can accumulate and lodge themselves in the renal pelvis or move into the narrow ureter. As the kidney stones move into the bladder, they can tear delicate tissue and cause severe pain and discomfort. They can also work their way further down the excretory passage and lodge in the urethra, causing a burning sensation, along with excruciating pain.
Dialysis Technology
The term “dialysis” means the exchange of substances across a semipermeable membrane. A dialysis machine is used for people whose kidneys cannot effectively process bodily wastes. The principles of diffusion and blood pressure both influence the operation of a dialysis machine.
Dialysis Technology
The term “dialysis” means the exchange of substances across a semipermeable membrane. A dialysis machine is used for people whose kidneys cannot effectively process bodily wastes. The principles of diffusion and blood pressure both influence the operation of a dialysis machine.
6 things the endocrine system is instrumental in:
regulating mood
growth and development
tissue function
metabolism
sexual function
reproductive processes
endocrine system
is a system of glandular tissues that produce and secrete special messenger molecules called hormones, into the blood
hormones
special messenger molecules. The word “hormone” means “to excite or set into motion.” Hormones are often produced in one part of the body and then travel in the blood to a target tissue cell, bind to it, and affect it in some way.
Target hormones + 2 examples
Target specific tissues and cells of the body, rather than all cells.
Parathyroid hormone—regulates calcium levels in the body (targets bone tissue)
Gastrin—stimulates cells of the stomach to produce digestive enzymes
Non-Target hormones + 3 examples
Impact many cells of the body, instead of just one specific cell type.
Growth hormone (GH) or somatotropin (STH)—regulates the development of long bones and cell division
Insulin—regulates blood sugar by increasing the permeability of all cells to glucose
Epinephrine (adrenalin)—is produced in times of stress to
There are two types of hormones that differ, both in chemical structure and action:
steroid and protein hormones.
There are two types of hormones that differ, both in chemical structure and action:
steroid and protein hormones.
Steroid hormones are
derivatives of cholesterol
- 3 types: male + female sex hormones, and cortisol
- composed of complex, fused rings of carbon, hydrogen, and oxygen molecules. Steroid hormones are not soluble in water but are soluble in fat.
The mechanism of action for steroid hormones
- hormones diffuse from the capillaries into the interstitial fluid and then into the target cell.
1. The hormones combine with receptor molecules located in the cytoplasm.
2, This hormone-receptor complex then moves into the nucleus of the cell.
- The hormone-receptor complex and attaches to a segment of DNA that has a complementary shape, causing transcription of an mRNA strand.
- The newly produced mRNA diffuses out of the nucleus and into the cytoplasm where it is translated into a specific protein.
Protein hormones
They contain chains of amino acids that vary in length.
They are soluble in water.
They bind at specific receptor sites
e.g. insulin and GH
The mechanism of action for protein hormones
- must work in a different way from steroid hormones as cannot cross the phospholipid bilayer easily.
- Some form a hormone-receptor complex that activates the production of an enzyme called adenyl cyclase, which, in turn, causes the cell to convert ATP into cyclic adenosine monophosphate (cyclic AMP).
- The cyclic AMP functions as a messenger, activating enzymes in the cytoplasm to carry out their normal functions.
describe the pituitary gland
- often called “the master gland,” because it exercises control over other endocrine glands.
- produces and stores several hormones. (ADH, oxytocin)
- small sac-like structure that is connected to the hypothalamus.
- has two lobes: the posterior lobe and the anterior lobe.
- controlled by the hypothalamus, which is part of the brain and the nervous system.
antidiuretic hormone
ADH, hormone responsible for increasing water reabsorbtion in urinary system
Thyroid-stimulating hormone (TSH)
- p gland hormone / anterior lobe
- impacts Thyroid gland
- Stimulates release of thyroxine from the thyroid. Thyroxine regulates cell metabolism
three types of neurons:
Sensory neurons
These neurons sense and relay information from the environment to the CNS for processing. They are located in clusters called ganglia.
Interneurons
These neurons link neurons within the body and are found mostly throughout the brain and spinal cord. They integrate and interpret the sensory information and connect neurons to outgoing motor neurons.
Motor neurons (also known as efferent neurons) These neurons send information to the “effectors.” Effectors are muscles, organs, and glands.
