Hormonal Communication Flashcards
endocrine system
a communication system using hormones as signalling molecules
hormones
proteins or steroid molecules that are released by endocrine glands into blood and they act as messengers carrying the signal to the specific target organ/tissue
target cells
for non-steroid hormones cells that posses a specific receptor on their membrane- shape is complementary to the hormone
adrenal cortex
outer layer of the adrenal gland
adrenal gland
one of a pair of glands lying above the kidneys which release adrenaline and other hormones (corticoids)
adrenaline
hormone which stimulates the body to prepare for fight or flight
adrenal medulla
inner layer of the adrenal gland
beta cells
found in the islets of Langerhans that secrete insulin
glucagon
hormone that causes an increase in blood glucose concentration
insulin
hormone released from the pancreas that causes blood glucose levels to go down
diabetes mellitus
condition which blood glucose levels can’t be controlled effectively
stem cells
unspecialised cells that have the potential to develop into any type of cell
types of hormones
protein and peptide hormones (derivatives of amino acids)- not soluble
steroid hormones- soluble so enter nucleus and have direct effect
endocrine glands
ductless glands that consist of a group of cells that manufacture and release a hormone directly via capillaries into the blood
endocrine organs
pituitary gland, thryoid gland, thymus, adrenal glands, pancreas, ovaries, testes
how do target cells work
for non-steroid hormones, must possess a specific receptor complementary to the shape of the hormone to initiate changes in the cell
each hormone is different so only the target cells with specific receptor will respond
how are target cells distributed
when receiving an endocrine signal, either grouped together in a target tissue or widely dispersed in a number of tissues
first messenger
non-steroid hormones, signalling molecules outside the cell that bind to the membrane and initiate an effect inside the cell
second messenger
first causes the release of another signalling molecule in the cell, stimulating a change in the activity of the cell
roles of the pancreas
digestion- secretes digestive enzymes
metabolism- regulation of carbs, lipids etc., produces primary messengers
2 main secretions of the pancreas
pancreatic juices containing enzymes secreted into the s. intestine
hormones secreted from islets of Langerhans into the blood
what enzymes does fluid from the pancreatic duct contain
pancreatic amylase, trypsinogen, lipase, sodium hydrogencarbonate to make it more alkaline
endocrine tissues
islets of Langerhans contains alpha and beta cells
alpha cells
secrete glucagon to raise glucose concentration
beta cells
secrete insulin to lower glucose concentration
glycogenesis
glucose converted to glycogen
glycogenolysis
glycogen converted to glucose
gluconeogenesis
breaking down of triglycerides and proteins
glycosuria
glucose in the urine
glucose levels must be constant (4-6mmol dm3) because
respiration is a continuous process in all living cells
high concentration of glucose affects the water potential of the blood plasma
hypoglycaemia
inadequate delivery of glucose to tissues and brain causing tiredness, irritability, even seizures, unconsciousness, death
hyperglycaemia
glucose concentration rises too high for long periods causing organ damage, osmotic water loss, damages blood vessels
how do hormones act on hepatocytes
when there is excess glucose, it is converted to glycogen and when glucose is needed it is converted back
hepatocytes
liver cells that can store glycogen
if blood glucose concentration rises too high
it is detected by beta cells, secrete insulin into the blood, travels through the body to target cells
insulin
a small protein and hormone of 51 a.a.
how do liver cells release glucose from glycogen
have a specific membrane receptor, insulin binds and causes glucose channels to merge with the membrane
if blood glucose concentration drops too low
detected by alpha cells, secrete glucagon into the blood to act on target cells
why is glucose concentration controlled by negative feedback
insulin and glucagon are antagonistic but fluctuate around the required concentration
glucagon
a small protein hormone containing 29 a.a.
diabetes mellitus
a condition in which the body is no longer able to produce sufficient insulin to control its blood glucose concentration
other names for type 1 diabetes
insulin-dependent or juvenile-onset diabetes because it starts in childhood
other names for type 2 diabetes
non-insulin-dependent diabetes
