Endocrine System 1

Question 1

What is the endocrine system made of?

Answer 1

• Hormones and glands

Question 2

What are all the organs of the endocrine system?

Answer 2

• Hypothalamus
• Pineal gland
• Pituitary gland
• parathyroid glands
• Thyroid gland
• Adrenal glands
• Pancreatic islets
• testes and ovaries

Question 3

What different methods are there that cells use to communicate

Answer 3

• Intercellular
• Paracrine
• Synaptic
• Endocrine

Question 4

what is intercellular communication?

Answer 4

• transport of ions and lipid soluble materials through connexons (gap junctions) to directly adjacent cells

Question 5

what is paracrine communication

Answer 5

• the use of chemicals (paracrine factors) to stimulate nearby target cells
• cells secrete paracrine factor into the extracellular fluid, which only affects close by cells where the concentration is high enough

Question 6

what is synaptic signalling?

Answer 6

• neurons signal across synapses using neurotransmitters which target a very specific group of cells

Question 7

what is endocrine signalling

Answer 7

• when cells secrete hormones into the blood, and the hormones target receptor cells in other tissues

Question 8

describe an endocrine gland

Answer 8

• ductless glands made of endocrine cells

- have good blood supply

Question 9

what are hormones

Answer 9

• organic chemical messengers produced and secreted by endocrine cells and glands
• bind to specific receptors in target cells
• stimulate gene expression and protein synthesis

Question 10

complete the table for the nervous system
communication method;
target;
response time;
range of effect;
response duration;

Answer 10

• neurotransmitters, nerves
• glands, muscles, neurones
• fast
• localised
• short term duration

Question 11

complete the table for the endocrine system
communication method;
target;
response time;
range of effect;
response duration;

Answer 11

• hormones, blood
• any cell with the receptor
• slow
• widespread
• long term

Question 12

what are the 2 mechanisms of hormonal action

Answer 12

• non-steroid action

- steroid action

Question 13

name the 3 divisions of hormones and their subdivisions

Answer 13

1) amino acid derivatives
2) peptide hormones
3) lipid derivatives (steroid and eicosanoids)

Question 14

what type of hormone is the largest

Answer 14

peptide hormone

Question 15

describe non-steroid action

Answer 15

• a non steroid hormone (amino acid derivative/ peptide hormone) acts as a first messenger binding to hormone receptor forming a complex
• the hormone receptor complex activates an intrinsic G protein
• the activated G protein activates an intra cellular protein (adenylate cyclase)
• this converts ATP into cAMP, cAMP activates kinase which has an excitatory effect on the cell

Question 16

what does the kinase enzyme do?

Answer 16

• adds a phosphate group to other molecules

Question 17

what type of hormone are non steroid hormones

Answer 17

• peptide hormones
• amino acid derivatives
• eicosanoids

Question 18

describe the other mechanism where the non-steroid hormone activates PDE

Answer 18

• a non-steroid hormone binds to a hormone receptor forming a complex
• this hormone receptor compex activates a G protein
• this G protein activates the intrinsic protein PDE (Phosphodiesterase)
• PDE converts cAMP into ATP which has an inhibitory effect on the cell

Question 19

how do anabolic steroids work

Answer 19

• these are steroid hormones which have receptors in muscles and stimulate muscle production

Question 20

what are the risks of anabolic steroids

Answer 20

• stunted growth of skeleton and maturation of sexual organs
• damages liver, cardiovascular and increases cholesterol
• reduces sperm count, causes baldness and prostate cancer risk in men
• women get facial hair baldness, stops their menstrual cycle

Question 21

describe steroid action

Answer 21

• steroid hormone diffuses across lipid bilayer
• it binds to receptors in the nucleus or cytoplasm activating or deactivating genes
• rate of DNA transcription changes in nucleus
• rate of translation is also affected altering the cells metabolic rate

Question 22

describe how thyroid hormones act

Answer 22

• cross the cell membrane by diffusion or a transport mechanism
• binds to nuclear or mitochondrial receptors
• activates specific genes to change the rate of mRNA transcription
• increasing metabolic activity

Question 23

what eventually happens to free hormones

Answer 23

• remain functional for about an hour

- bind to target receptors or are broken down by liver, kidney or enzymes in blood plasma

Question 24

what eventually happens to thyroid and steroid hormones

Answer 24

• remain in circulation much longer as they are not bound

- nearly all attach to transport proteins

Question 25

what controls the regulation of the endocrine system

Answer 25

- the hypothalamus and pituitary gland

Question 26

describe the hypothalamus and pituitary gland in detail

Answer 26

- hypothalamus is superior to the pituitary gland - pituitary gland is made of 2 lobes, the posterior and anterior, and a capillary pathway called the infundibulum joining the 2 organs

Question 27

describe the pathway which ends in the release of stimulating hormones

Answer 27

- the hypothalamus secretes many types of regulatory hormones into the primary plexus - this travels down the infundibulum into the secondary plexus in the anterior lobe - the hormones then move out of the blood stream into the anterior pituitary lobe stimulating the release of stimulating hormones

Question 28

what are the functions of the hypothalamus

Answer 28

- to secrete regulatory hormones into to primary plexus - to control the production and release of ADH and oxytocin, stored in the posterior lobe - to control sympathetic output to the adrenal glands

Question 29

what is the anterior lobe sectioned into and their jobs

Answer 29

- pars tuberalis - pars distalis (secretes stimulating hormones) - pars intermedia (middle bit, secretes MSH)

Question 30

what is the hypophyseal portal system and describe it

Answer 30

- the blood supply to the pituitary and hypothalamus - superior hypophyseal artery runs into the hypothalamus, forming the primary plexus, which runs into the anterior lobe forming the secondary plexus and leaves - the inferior hypophyseal artery enters the posterior pituitary lobe and leaves - both leave as hypophyseal veins

Question 31

how does the endocrine system rely on a negative feedback system

Answer 31

- once a stimulating hormone released from the anterior lobe reaches a target organ, the target organ releases hormones for a target cell - this secondary hormone travels via the blood supply and inhibits the production of the stimulating hormone and releasing hormone