chemical coordination Flashcards
hormones
proteins with a specific function, hormones are chemical messengers made by endocrine glands, they are secreted directly into the blood and can travel to all parts of the body, they act on target organs, cells in target organs have special receptors that can detect the presence of a specific hormone e.g liver cells have insulin receptors that can detect and respond to insulin
glands
glands secrete substances
two types of glands
endocrine and exocrine
exocrine glands
exocrine glands secrete substances via ducts: saliva glands secrete saliva through saliva ducts, tear glands secrete tears through tear ducts
endocrine glands
endocrine glands are ductless and secrete hormones directly into the bloodstream, adrenal glands secrete adrenaline into the blood
nervous system vs endocrine system
transmission:
N- nerve impulses transmitted through nerve cells
E- hormones transmitted through the bloodstream
speed:
N- nerve impulse travel fast, ‘instant’ effect
E- hormones travel slower, take longer to act
duration:
N- response is usually short-lived
E- response is usually longer-lasting
location:
N- impulses act on individual cells such as muscle fibres, so have a very localised effect
E- hormones can have widespread effects on different organs
pituitary gland
secretes the:
follicle stimulating hormone (FSH)- stimulates egg development and oestrogen secretion in females and sperm production in males
luteinising hormone (LH)- stimulates egg release (ovulation) in females and testosterone production in males
antidiuretic hormone (ADH)- controls the water content of the blood
thyroid gland
secretes thyroxine which controls the body’s metabolic rate (how fast chemical reactions take place in cells)
pancreas
secretes:
insulin- lowers blood glucose concentration
glucagon- raises blood glucose concentration
adrenal glands
secretes adrenaline which prepares the body for physical activity
testes
secrete testosterone which controls the development of male secondary sexual characteristics
ovaries
secrete:
oestrogen- controls the development of female secondary sexual characteristics
progesterone- regulates the menstrual cycle
endocrine glands
the pituitary gland is in the brain and releases many different hormones, it is connected to the hypothalamus, this is where the nervous system and the endocrine system are linked together
the pancreas
the pancreas is both an exocrine gland and an endocrine gland
exocrine function: secrete digestive enzymes into the small intestine through the pancreatic duct
endocrine function: secrete insulin and glucagon directly into the blood
adrenaline
when you are frightened, excited, or nervous your adrenal glands secrete adrenaline into your blood
adrenaline acts on many different target organs and tissues
changes in the body due to adrenaline
- breathing rate increases and breaths become deeper, taking more oxygen into the body
- the heart beats faster, sending more blood to the muscles so that they receive more glucose and oxygen for respiration
- blood is diverted away from the intestine and into the muscles
- in the liver, stored carbohydrate (glycogen) is changed into glucose and released into the blood. the muscle cells absorb more glucose and use it for respiration
- the pupils dilate, increasing visual sensitivity to movement
- body hair stands upright, making the animal look larger to an enemy
- mental awareness is increased so reactions are faster
insulin and glucagon
hormones to help control blood glucose concentration to keep it at a constant level of approx. 1g/dm3 of blood
insulin, glucagon function example
insulin
stimulus: eating four donuts, increase in blood glucose concentration, cells in pancreas secrete insulin into the blood, target organs: muscles and liver take in glucose and store it as glycogen, blood glucose decreases and pancreas stops secreting insulin
glucagon
stimulus: working out at the gym, decrease in blood glucose concentration, cells in the pancreas secrete glucagon into the blood, target organ: liver converts glycogen back into glucose and releases into the blood, blood glucose increases and pancreas stops secreting glucagon
type 1 diabetes
symptoms: increased thirst and glucose found in urine
onset: childhood
causes: genetic
explanation: pancreas does not make insulin
treatment: monitoring blood glucose and taking insulin injections
