the endocrine system

Question 1

what are exocrine glands

Answer 1

glands that secrete their products into a duct

Question 2

what are endocrine glands

Answer 2

glands that release hormone into the blood

Question 3

what are hormones

Answer 3

chemical messengers carried by the blood to target cells
they are released by glands to elicit a response
only affect specific target cells
operate in synchrony to nervous system

Question 4

functions of endocrine system

Answer 4

regulate chemical composition and volume of internal environment
control growth and development
regulate operation of reproductive system
help establish circadian rhythm

Question 5

structural classes of hormones

Answer 5

amines
peptides
steroids

Question 6

mechanism sof hormone action

Answer 6

carried in blood to specific destinations
-receptors found inside target cells for steroid and thyroid hormones
-receptors on plasma membrane for peptide hormones and catecholamines

Question 7

what does the responsiveness of a target cell depend on

Answer 7

hormone concentration in the blood
abundance of target cell hormone receptors
influences exerted by other hormones

Question 8

what are the three types of hormone effects

Answer 8

permissive
synergistic
anatgonistic

Question 9

how is secretion of hormones controlled

Answer 9

1. plasma concentrations an ion or nutrient that the hormone regulates
2. neural input to the endocrine cells (neurones in hypothalamus secrete hormones in response to input from the ANS)
3. other hormones- secretion of a particular hormone is often directly controlled by blood concentration of another hormone

Question 10

what is a tropic hormone

Answer 10

a hormone that stimulates the secretion of another hormone

Question 11

relationship between hypothalamus and pituitary gland

Answer 11

hypothalamus synthesises hormones and sends them to pituitary gland

Question 12

posterior pituitary gland

Answer 12

neural extension of hypothalamus
hormones passed from hypothalamus down infundibulum by axons
releases hormones

Question 13

anterior pituitary gland

Answer 13

secretes groth hormone, TSH, adrenocorticotropic hormone, prolactin, FSH and LH
secretion controlled by hypophysiotropic hormones from hypothalamus via portal vessels

Question 14

thyroid gland

Answer 14

releases thyroid hormones
produces thyroxine (T4) and triiodothyronine (T3)
TSH production controlled by negative feedback or T3 and T4
increase in T3 and T4 associated with increasing oxidative substrate metabolism and increasing mitochondrial enzyme activity
T3 required for normal production of growth hormone

Question 15

cortisol

Answer 15

secretion during stress is mediated by hypothalamus-anterior pituitary gland system

Question 16

physiological functions of cortisol in non-stressful situations

Answer 16

-affects responsiveness of smooth muscles to adrenaline and noradrenaline
-required to maintain certain enzyme concentrations involved in homeostasis
-anti-inflammatory and immune functions

Question 17

physiological functions of cortisol in stressful situations

Answer 17

-metabolism stimulated to break down protein
-liver stimulated to take up amino acids and convert them to glucose
-plasma glucose levels maintained
-breakdown of triglycerides for fuel
-enhamced vascular reactivity
-inhibition of non-essential functions

Question 18

growth hormones

Answer 18

secretion stimulated by growth hormone releasing hormone (GHRH) and inhibited by somatostatin (SST)
acts directly on cells to stimulate protein synthesis

Question 19

testosterone

Answer 19

produced in testes in males
produced in ovaries and adrenal cortex in females
promotes muscle growth and development of male characteristics