homeostasis Flashcards
what are some examples of negative feedback systems
in the body
control of blood sugar levels by insulin and glucagon, control of temperature and water balance in the body
what are some examples of positive feedback systems in the body
blood clotting, oxytocin produced during childbirth
What is meant by the term “ectotherm”?
An animal which depends on the environment to regulate its internal body temperature.
What is meant by the term “endotherm”?
An animal that maintains a constant internal body temperature regardless of the external temperature by generating heat through metabolic processes.
In endotherms, temperature receptors are located in which two parts of the body?
The skin and the hypothalamus.
which part of the brain is involved with temperature regulation
the hypothalamus
What is seen in endotherms in response to a rise in core body temperature?
vasodilation, sweating and lowering hair by relaxing hair erector muscles.
What is seen in endotherms in response to a fall in core body temperature?
vasoconstriction, shivering and raising hair by contracting hair erector muscles.
Define the term excretion.
The removal of waste products of cell metabolism from the body.
What are the three main waste products which need to be excreted in mammals?
Carbon dioxide, bile pigments and urea.
Which process in the liver removes the amine group from amino acids when breaking down excess proteins?
deamination
what are the nephrons in a kidney
the microscopic functional units of the kidney responsible for producing urine
What are the four main mechanisms that must occur in the nephron to convert filtrate into urine?
ultrafiltration, selective absorption, secretion and excretion
What are the five main structures found in a nephron?
bowman’s capsule, proximal convoluted tubule, Loop of Henle, Distal convoluted tubule and collecting duct.
what is the glomerulus and what does it do
the knot of capillaries found within the Bowman’s capsule, ultrafiltration
what does ultrafiltration in the bowman’s capsule form?
glomerular filtrate
which has a larger lumen, the afferent or afferent arteriole
afferent arteriole
what are the main substances in glomerular filtrate
Urea, glucose, salt, Cl- and water
what can’t leave the blood plasma in the bowman’s capsule
blood cells and large plasma proteins
what are hepatocytes
in the liver, they synthesise most plasma proteins, carry out transamination and deamination, and detoxification of the blood
what is deamination
braking down amino acids by removing the ammine group to produce ammonia and keto acid which can be used in cellular respiration or converted into lipids or cholesterol
what is the ornithine cycle
conversion of ammonia into urea, occurs in the hepatocytes mitochondria and cytoplasm
what are the 3 stages of the ornithine cycle
- NH3, CO2, ornithine, and ATP produce citrulline and water
- NH3, ATP and citrulline produce arginine and water
- Arginine and water produce urea and ornithine
what two enzymes do hepatocytes contain for the detoxification of ethanol in the blood
alcohol dehydrogenase, aldehyde dehydrogenase
what is glycogenesis
The conversion of glucose to glycogen
define glycogenolysis
the conversion of glycogen to glucose
what is gluconeogenesis
the conversion of amino acids and glycerol to glucose
what two main hormones are produced by the adrenal cortex
aldosterone and cortisol
what two main hormones are secreted by the adrenal medulla
adrenaline and noradrenaline
what hormone do alpha cells in the islets of Langerhans produce
glucagon
which hormone do beta cells in the islets of langerhans produce
insulin
where is insulin in insulin injections obtained from
genetically modified bacteria
what is the blood vessel that supplies oxygenated, nutrient-poor blood to the liver
hepatic artery
what is the blood vessel that supplies deoxygenated, nutrient rich-blood to the liver
hepatic portal vein
what blood vessel carries deoxygenated blood out of the liver to the liver
hepatic vein
how does the liver help control blood glucose concentration in the blood
convert glucose into glycogen
What is the role of the hypothalamus in osmoregulation?
The hypothalamus contains osmoreceptors which are sensitive to changes in the water potential of the blood. They control the release of ADH by the posterior pituitary gland.
How does ADH increase the absorption of water
by increasing the permeability of distal convoluted tube and the collecting duct
How does a pregnancy test work?
Pregnancy tests contain monocolonal antibodies attached to coloured beads. These antibodies are complementary to hCG.
When hCG is present in the urine, it binds to these antibodies and the complexes move into a new zone which contains immobilised antibodies. The complex binds to these and the coloured beads create a blue line, indicating pregnancy.
what is the purpose of the second line of a pregnancy test
acts as a control
How do doctors estimate the glomerular filtration rate?
They measure the concentration of creatine in the blood.
