D3.3 homeostasis Flashcards
homeostasis
The ability of the body to seek and maintain equilibrium and maintain conditions optimal for survival.
what are examples of internal conditions which are monitored in body
body temp, ph glucose concentration, osmotic concentration
positive feedback
A mechanism by which a system responds to changes in its internal or external environment by amplifying the direction of the change, often leading to a cascade of events.
negative feedback
A mechanism by which a system responds to changes in its internal or external environment by reversing the direction of the change, thereby maintaining homeostasis.
exocrine tissue
The system for secreting substances through ducts onto surfaces of the body. Examples are sweat and digestive enzymes.
endocrine tissue
The system for secreting hormones from glands into the blood. These hormones help control body functions.
what are islets of langerhans
Clusters of cells in the pancreas that produce hormones insulin and glucagon.
pancreatic endocrine cells
insulin importance and secretion for regulation of glucose
Insulin is produced and secreted by the beta cells of the islets of Langerhans in response to rising blood glucose levels. It stimulates glucose uptake from the blood into the cells.
glucagon importance and secretion for regulation of glucose
Glucagon is produced and secreted by the alpha cells of the islets of Langerhans in response to decreasing glucose levels. It stimulates the liver to release stored glucose into the bloodstream.
what happens when the blood glucose level rises above the normal range:
-Beta cells of the islets of Langerhans release insulin into the bloodstream.
-Insulin promotes (mainly) cells of the liver, muscles and fat tissue to take up glucose from the blood to decrease the blood glucose level. The glucose is stored as glycogen in the cells of muscle and liver, or as fat in the cells of fat tissue, for later use.
-As the blood glucose levels decrease, the secretion of insulin also decreases.
what happens when If the blood glucose level falls below the normal rang
-Alpha cells of the islets of Langerhans release glucagon into the bloodstream.
-Glucagon promotes (mainly) the cells of liver and fat tissue to break down glycogen and lipids and release the glucose into the blood until the level of blood glucose increases to the normal range.
-As the blood glucose levels increase, the secretion of glucagon also decreases.
what causes hyperglacaemia
Insufficient insulin production or ineffective use of insulin will result in high levels of blood glucose. Continued high blood glucose concentration
hormonal disorder that causes hyperglycaemia is called diabetes.
what happens to individuals with diabetes
cells cannot obtain enough glucose from the blood. Cells start to burn the body’s supply of fats and proteins. Since the digestive system continues to absorb glucose, the glucose concentration in the blood can become extremely high.
The kidneys start filtering excess glucose from the blood. Kidneys also draw water from blood to dilute the urine which causes dehydration of the body. The person becomes unusually and continually thirsty
what are the 2 types of diabetes
type 1, type 2
type 1 diabetes
insulin-dependent or early onset diabetes
unable to produce insulin. Insufficient insulin production leads to chronically elevated levels of glucose in the bloodstream – hyperglycaemia.
no known cure, must manage their blood glucose levels through a combination of insulin therapy, dietary modifications and regular exercise.
what are risk factors of type 1 diabetes
family history, age (younger), race, poor nutrition
symptoms of type 1 diabetes
feeling more thirsty
unirantion increase
very hungry
blurred vision
weight loss
tired
related health problems of type 1 diabetes
loss of eye sights
foot problems
heart disease
high blood pressure
kidney disease
stroke
nerve damage
what is type 2 diabetes
Insulin-independent or late-onset diabetes
insulin is produced and secreted into the blood, cells are insensitive to insulin and they are said to be ‘insulin resistant’
pancreatic beta cells start to produce more insulin and become exhausted.
type 2 diabetes can be reversed by moderate weight loss, regular physical activity and a healthy diet.
risk factors for type 2 diabetes
age (increase)
weight (obese)
lack of exercise
family history
smoking
hypertension
symptoms of type 2 diabetes
frequent urination
increased thirst
fatigue
weight loss
blurred vision
slow healing of wounds
related health problems to type 2 diabetes
heart disease and stroke
eye problems
foot problems
kidney disease
nerve damage
thyroid disease
thermoregulation
The process by which the body maintains a stable internal temperature despite changes in the external environment.
negative feedback
thermoregulation is coordinated where
in the nervous system and the processes of temperature control are centred in the hypothalamus of the advanced animal brain.
whats the importance of the pituitary gland
acts as a major endocrine gland that releases hormones into the bloodstream.
how are birds and mammals are able to detect differences in temperature.
specialised nerve called thermoreceptors
The thermoreceptors in the skin are called peripheral thermoreceptors. Thermoreceptors inside the body are central thermoreceptors.
importance of hypothalamus in thermoregulation
The hypothalamus integrates signals from the peripheral and central thermoreceptors and initiates physiological and behavioural responses as a negative feedback mechanism to regulate body temperature.
what happens in cooler enviornment in terms of mechanisms of thermoregulation
The hypothalamus stimulates the pituitary gland.
The pituitary gland releases thyroid stimulating hormone (TSH) to stimulate the thyroid gland.
The thyroid gland produces a hormone called thyroxin. The primary role of thyroxin is to increase the metabolic rate of body cells, which will result in more heat.
The production of TSH is an example of a negative feedback loop. The release of TSH is decreased and stopped if the levels of thyroxin produced are very high.
When the body temperature increases, signals from peripheral and central thermoreceptors stop the hypothalamus from producing TSH.
describe thermoregulation in humans in cold enviornment
-skeletal muscles repeated involuntary contractions= shivering, generates heat to raise body temp
-muscles in skin contract, makes hair in skin stand up trapping heat in the layer of air between the skin and the hair. This increases the insulating effect of body hair.
vasoconstriction, reduces blood flow in peripheral blood vessels, keeping blood close to the core and vital organs, conserving heat
describe thermoregulation in humans in hot enviornment
glands in the skin secrete sweat, when water in sweat evaporates carries heat out of the body, in a mechanism called evaporative cooling
vasodilation of blood vessels close to skin brings more blood to surface of body, blood carries heat to body surface to increase heat loss
explain role of fat-storing adipose tissue
fat-storing adipose tissue also contributes to thermoregulation. Brown adipose tissue cells are full of mitochondria.
Normally, during aerobic respiration in mitochondria, monomers are broken down, and these energy-producing reactions are coupled with ATP production.
However, the mitochondria in brown adipose tissue cells can release energy without producing ATP, to increase body heat when it is cold outside. This process is called uncoupled respiration
osmoregulation
The regulation of the body’s water balance and solute concentration to maintain homeostasis.
whats the osmoregulation organs in mammals
kidneys
what are the functions of the kidney
regulation of water and ion balance (osmoregulation)
removal of toxins and metabolic waste products (excretion)
production of hormones, and control of blood pressure
nephron
The functional unit of the kidney that filters blood, reabsorbs useful substances and excretes waste products in the form of urine.
blood enters the kidney through
renal artery, the top one
bowmans capsule
A cup-shaped structure in the nephron of the kidney that surrounds the glomerulus and collects the filtrate.
Highly porous wall which collects the filtrate
glomerolous
Knot-like capillary bed where high-pressure filtration takes place
loop of henle
Hairpin shaped tube with a descending and ascending limb; water and salt reabsorption takes place here
DCT distille convulated tubule
Another twisted section of the nephron, where water and salts are reabsorbed back into the blood; also contains many mitochondria and microvilli
afferant arteriole
Brings blood from the renal artery
PCT proximal convuluted tubule
Twisted section of the nephron where water, nutrients and salts are reabsorbed back into the blood; contains many mitochondria and microvilli
collecting duct
A slightly wider tube that carries the filtrate to the renal pelvis
efferent arteriole
A narrow blood vessel that restricts blood flow, which helps to generate the pressure needed for filtration
receptor
detects stimulus and transforms it into electrical impulses, light repectors thermal receptos…
effector
perform the response through actions, muscles or glands
response
cancels out stimulus (negative feedback) mechanism (cancels out the action caused by stimulus)
homeostasis of body temp, description
thermoregulation= detected by thermal receptors in skin
control center= hypothalamus thermo regulatory centre
what happens when body temp too low
skeletal muscle- shivering
arteriolr contraction- vasoconstriction
skin erector muscle- piloerection
all are bervous messengers
what happens when body temp too high
sweat glands (endocrine)- sweating
arteriole relaxation (nervous)- vasodilation
thirst
homeostasis of blood ph,description
detected by chemo receptors or ph receptors in aorta and carotid arteries
control center= medulla oblongata (brasin stem)
what happens when blood ph too low
excess co2 in blood forms H2, co3 makes blood acidic
messenger are all nervous
diaphragm and intercostal muscle- increased ventilation
homeostasis of blood glucose, description
glucoregulation
detected by chemoreceptors in the pancreas
cntrol center= pancreas
what happens when blood glucose too low
hypoglacaemia
glucagon (endorcirn- breaks down glycogen in liver or muscles into glucose
what happens when blood glucose too high
hyperglacaemia, insulin (endocrine)- increase uptake of blood glucose by body cells store excess of blood glucose in liver or musckes glycogen
description of homeostasis of blood osmolarity
osmoregulation, amount of solutes in a sovlent detected by osmoreceptors in collecting duct in nephron
control centre= hypothalamus (osmoregulatory centre) and posterior pituitary gland
describe what happens when blood osmolarity too high
blood is hypteronic person is dehydrated
ADH (endocrine)- removes water from blood, urine more concentrated (darker in cokour) feeling of thirst
describe the feedback mechanism
input ( stimulus produces a change)
process (change sensed by receptor and communicated to control centre)
output (control centre responds, there is an effect of the response)
feedback (output becomes new inout and cycle continues)
negative feedback, description - homeostasis uses
cancels out output from the stimulus eg. thermoregulation, glucoregulation, omoregulation etc.
positive feedback description
stimulates output from the stimulus eg. ontraction of uters by oxytocin milk ejection and production by prolaction and oxytocin
ejestion
undigested material that has been ingested (faeces)
lack of enzyme cellulase necessary to break down fibre plant material
excretion
removal of waste toxic products in excess produced by the metabolism (eg.urea= kideny co2= lungs sweat=skin)
osmoregulation
regulation fo the volume of water in the blood by monitoring the blood solute conc (eg.nacl)
kidneys
filtration unit, blood forms urine
ureters
transports urine kidney to bladder
bladder
holds urine
urethre
excretes urine
renal vein
above renal artery, carries balanced blood away from the kidney
renal artery
below renal vein, thicker, carries unbalanced blood into kidney
pelvis
interior part, collecting ducts deliver urine to pelvis to be passed on to the ureter
medulla
middle part of kidney
reabsorption of water
cortex
outer part of kidney
ultrafiltration selective reabsoprtion blood contents
ureter
carries urine to bladder
compare blood from renal artery to renal vein
renal artery= unbalanced or unfiltered blood as it contains high levels of
-oxygen, plasma proteins, amino acids, glucose
10%water, 90%urea, 50%nacl ( what is excreted=urine
renal vein= balanced blood/ filtered blood
100% plasma proteins
100%amino acids
100%glucose
co2 and oxygen is used for cellular respiration
90% water+10%urea+50%nacl
composition fo blood in renal artery and renal vein simpistic
renal artery:
oxygen, same amount of glucose, same amount of proteins, more water nd salts, more urea
renal vein
carbon dioxide, same amount of glucose, same amount ofproteins, less water and slats, much less urea
what are the 4 steps of kidney fucntions
ultrafiltration
reabosrption of (glucose, salt, water)
osmoregulation
excretion
renal capsule
ultrafiltration
glomerolous
delivers blood
proximal convoluted tubule
selective reabosrption
loop of henle
osmoregulation
distal convoluted tubule
secretion of toxins int urine
collecting duct
delivers urine to pelvis
bowmans capsule
renal capsule + glomerolous
describe 1 ultrafiltration
happens in renal capsule in cortex of kidney
caused by high blood pressure coming from renal artery and by cenestrations (pores) in the glomerolous
forces the plasma nside blood to squeeze out from the glomerolous into the renal capsule formng the glomerular filtrate
only small molecules can squeeze out to form the filtrate such as water glucose urea salts and amino acids
describe first step of ultrafiltration
unbalanced blood arriving from the renal artery so it has high blood pressure
describe step 2 of ultrafiltration
glomerular filtrate only small molecules; glucose, water, ions amino acids and urea
describe step 3 of ultrafiltration
plasma proteins, platlets and blood cells; large molecules:remain in the blood and return to renal vein
describe selective reabsorption
happens in PCT, in cortex of kidney
useful molecules inside the glomerular filtrate are reabosrbed into the bood glomerular filtrate
usfeul molecules are reabsorbed (wagiu):
water- reabosrbed osmosis
amino acids +glucose are reabsorebed via active transport
ions= reabsorbed via diffusion
filtrate formed after reabsorption is made of urea, water, salts= diluted urine formation
describe osmoregulation
happens in loop of henle and collecting duct
is the control of water and solute concentration in the body fluids 9eg.blood plasma)
job of loop of henle= generate high concentration of sultes (low concentration of water) in the tissue fluid of the medulla compared to filtrate in nephron aids the reabsorption of water in the collecting duct
hormone ADH balances the water concentration of blood by changing the permeability of the collectng duct
describe 3A osmoregulation in the loop of henle
nacl is pumped into the bloodstream, this icnreases the blood osmolarity (blood is hypertonic) to higher levels than the filtrate (comparing both, teh filtrate is hypertonic)
2. water moves by osmosis from hypotonic enviornment filtrate towards hypertonic solution= blood (less hypertonic)
3. this results in water moving away from filtrate to avoid water loss in excretion
direction of filtrate vs blood is contrary.
3B osmolarity in collecting duct
filtrate coming from the ascending loop of henle towards the collecting duct is hypertonic in comparison to the blood To avoid water loss, the hypothalamus detects the low blood osmolarity and sends an impulse to the pituitary gland to release ADH
describe aquaporin part of osmoregulation
ADH aquaporin are inserted into cell membrane increasing flow as H2O out of tubule
ADH stimulates the insertion of aquaporins (protein channels that make water move by facilitated diffusion)
describe cold stimulus, effector response and effect
skeletal muscle- involuntary rythmic contraction (shivering)- themogenisis (heat production)
muscle layer in arterioles (in skin)- vasoconstriction- reduces heat loss through skin
Piloerector muscles in skin- piloerection- traps air layer for insulation
thyroid gland- releases thyroxin- increases basal metabolic rate
BAT(brown adipose tissue)- uncoupled respiration- thermogenisis (heat production)
describe the use of adipose in thermoregulation
adipose= fat
brown adipose tissue is used
uncoupled respiration= oxidation/ burning of fatty acids once all glucose source is used up. Given the high numbers of mitochondria inside BAT, the energy released in the form of heat is very high
describe hot stimulus effector, response and effect
muscle layer in arterioles (in skin)- vasodilation- increases heat loss through skin
sweat glands- secrete sweat- increases heat loss through skin
describe blood glucose regulation with high glucose
high glucsoe conc in blood
capillary, high conc detected by beta cells in pancreas
beta cells release and produce insulin (peptide hormone hydrophilic)
increase uptake glucose by body cells through opening of gut ( glucose trnasport) receptors increases condensation of glucose into glycogen
glucose stored as glycogen
describe blood glucose regulation with low glucose
low blood glucose concentration in blood capillary
detected by alpha cells in pancreas
alpha cells produce and release glucagon
glucagon (peptide hormone hydrophilic) increases hydrolysis of glycogen into glucose
glycogen broken down into glucose
explain healthy insulin receptor process detailed
beta cells in pancreas secretes insulin when glucose blood levels are high
since insulin is hyrophilic and therefore cant freely pass through plasma membrane it binds to an integral transmembrane protein receptor called RTK which acts as an enzymes
RTK causes a cascade of intracellular metbolic reactions, ultimately leading to the influx of glucose from the blood to the cell
Glut acts as a channel facilitating the passive movement of glucose which can be used for cellular respiration stored as glycogen
explain type 1 diabetes why insulin doesnt work
beta cells dont secrete insulin without insulin RTK is not activated consequently GLUTE not activated
thus high blood glucose conc
explain type 2 diabetes why insulin doesnt work
Either RTK is not activated properly
not having enough RTK
RTK is not sensitive to insulin (insulin resistance)
