chemical coordination

Question 1

hormones

Answer 1

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

Question 2

glands

Answer 2

glands secrete substances

Question 3

two types of glands

Answer 3

endocrine and exocrine

Question 4

exocrine glands

Answer 4

exocrine glands secrete substances via ducts: saliva glands secrete saliva through saliva ducts, tear glands secrete tears through tear ducts

Question 5

endocrine glands

Answer 5

endocrine glands are ductless and secrete hormones directly into the bloodstream, adrenal glands secrete adrenaline into the blood

Question 6

nervous system vs endocrine system

Answer 6

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

Question 7

pituitary gland

Answer 7

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

Question 8

thyroid gland

Answer 8

secretes thyroxine which controls the body’s metabolic rate (how fast chemical reactions take place in cells)

Question 9

pancreas

Answer 9

secretes:
insulin- lowers blood glucose concentration
glucagon- raises blood glucose concentration

Question 10

adrenal glands

Answer 10

secretes adrenaline which prepares the body for physical activity

Question 11

testes

Answer 11

secrete testosterone which controls the development of male secondary sexual characteristics

Question 12

ovaries

Answer 12

secrete:
oestrogen- controls the development of female secondary sexual characteristics
progesterone- regulates the menstrual cycle

Question 13

endocrine glands

Answer 13

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

Question 14

the pancreas

Answer 14

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

Question 15

adrenaline

Answer 15

when you are frightened, excited, or nervous your adrenal glands secrete adrenaline into your blood

adrenaline acts on many different target organs and tissues

Question 16

changes in the body due to adrenaline

Answer 16

• 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

Question 17

insulin and glucagon

Answer 17

hormones to help control blood glucose concentration to keep it at a constant level of approx. 1g/dm3 of blood

Question 18

insulin, glucagon function example

Answer 18

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

Question 19

type 1 diabetes

Answer 19

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