D3 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