Hormone structure and action

Question 1

forms of chem communication

Answer 1

autocrine

neurocrine

paracrine

endocrine

pheromone

allomone

Question 2

autocrine comm

Answer 2

Chemical released by cell affects its own activity

Question 3

neurocrine (synaptic) comm

Answer 3

Chemical released by neuron diffuses across synaptic cleft and affects postsynaptic membrane

Question 4

paracrine comm

Answer 4

Chemical released into extracellular env and affects nearby target cells

Question 5

endocrine (hormone) comm

Answer 5

Chemical released into bloodstream and selectively affects (distant) organs

Question 6

pheromone comm

Answer 6

Chemical released into external env and affects conspecifics (members of same species)

Question 7

allomone comm

Answer 7

Chemical released into external env and affects heterospecifics (members of other species)

Question 8

what are hormones

Answer 8

Bioregulators of endocrine system

Secreted by specialised cells directly into the blood

Selectively act on target cells

chem messengers

Question 9

3 main types of hormones

Answer 9

protein (peptide)

amine

steroid

Question 10

transmission of endocrine signals

Answer 10

target cell has to have right type of receptor

Question 11

protein hormones

Answer 11

Chain of AAs

Peptide hormones have short chain

Question 12

types of protein hormones

Answer 12

Oxytocin

Vasopressin

Prolactin

Insulin

Glucagon

Growth hormone (GH)

Thyroid-stimulating hormone (TSH)

Luteinising hormone (LH)

Follicle-stimulating hormone (FSH)

Releasing hormones, inc. corticotropin-releasing hormone (CRH), gonadotropin-releasing hormone (GnRH)

Most released from hypothalamus

Question 13

amine hormones

Answer 13

Modified single AA (a.k.a. monoamine hormones)

Smaller and simpler than protein hormones

Question 14

types of amine hormones

Answer 14

Adrenaline (epinephrine)

Noradrenaline (norepinephrine)

Thyroid hormones

Melatonin

Question 15

action of protein and amine hormones

Answer 15

don’t travel into cell

Bind to specific receptors on outside of cells

Act ‘rapidly’ (secs-mins)

Can have prolonged effects

Sensitivity can be altered by increasing (upregulating)/decreasing (downregulating) numbers of receptors on cell

Stored in vesicles and secreted on demand

Question 16

steroid hormones

Answer 16

Derived from cholesterol

Made from 4 interconnected carbon rings

Soluble in lipids - dissolve in fats - imp consequences - cross cell membrane

Question 17

types of steroid hormones

Answer 17

Oestrogen

Progestins

Androgens (e.g. testosterone)

Glucocorticoids

Question 18

action of steroid hormones

Answer 18

Act on specific receptors inside cells

Act ‘slowly’ (hrs)

Gave long-lasting effects via transcription of DNA

Sensitivity can be altered by presence/absence of co-factors necessary for cells to respond

Cannot be stored - must be synthesised on demand

Question 19

endocrine glands/organs

Answer 19

Exocrine - release substances onto surface - sweat, salivary, tear ducts

heavily vascularised with blood vessels

follicles of endocrine cells secrete hormones into lumen

hormone transported into thin-walled capillary and flows into bloodstream - 1 cell thick

ductless - no ducts leading to bloodstream

Question 20

endocrine system subdivisions

Answer 20

Endocrine - typically respond to levels of chems in blood - not directly controlled by nervous system

Question 21

what controls hormone production?

Answer 21

Needs to be constantly managed

Feedback loops play key role

Usually involved neg feedback: high levels hormone inhibit further production —> maintains homeostasis

Sometimes involves pos feedback

E.g. oxytocin secretion in milk letdown reflex

Question 22

key hormone production pathways

Answer 22

Autocrine feedback

Target cell feedback

Brain reg

Brain and pituitary reg

Question 23

autocrine feedback example

Answer 23

prostaglandins - inhibit acid secretion - e.g. HCl

Question 24

target cell feedback example

Answer 24

insulin pathway - reg of blood sugar

Question 25

brain regulation example

Answer 25

alarm response

Question 26

brain and pituitary regulation example

Answer 26

temp regulation

Question 27

the pituitary gland

Answer 27

Consists of 2 parts, do diff things: - Anterior pituitary/adenohypophysis - Posterior pituitary/neurophypophysis

Question 28

how do hormones act within the body?

Answer 28

ST effects - e.g. oxytocin milk letdown reflex LT effects - e.g. growth hormone: bone growth

Question 29

ST effects example

Answer 29

Oxytocin: milk letdown reflex

Question 30

LT effects example

Answer 30

Growth hormone (GH/somatotropin): reg of bone growth Some LT effects can be reversed e.g. psychosocial dwarfism

Question 31

organisms use several types of chem communication

Answer 31

Hormones just one variety of modes chem communication between cells Ntms cross tiny gap during synaptic transmission Autocrine signal and paracrine signals Pheromones and allomones

Question 32

hormonal actions can be organised according to general principles

Answer 32

Unlike neuronal signalling, hormones spread more slowly and act throughout the body Some hormones act on receptors in wide variety of cells and can coord influences on activities of most cells in the body Other hormones have receptors in only certain special cells/organs

Question 33

peptide and amine hormones

Answer 33

Bind to receptor molecules at surface of target cell membrane and activate second-messenger molecules inside cell Steroid hormones pass through membrane and bind to receptor molecules inside cell, ultimately regulating gene expression

Question 34

feedback control mechanisms regulate the secretion of hormones

Answer 34

Neg feedback system monitors and controls rate of secretion of each hormone Hormone acts on target cells, leading them to change amount of substance they release In simplest case, hormone also acts on endocrine cells, and this regulates further output of endocrine gland Other hormones controlled by releasing hormone from hypothalamus that regulates release of anterior pituitary tropic hormone, which in turn controls secretion by endocrine gland Endocrine gland hormone then provides neg feedback to hypothalamus and pituitary

Question 35

the posterior pituitary

Answer 35

Posterior pituitary hormones manufactured by neuroendocrine cells in supraoptic and paraventricular nuclei of hypothalamus, which send axons down pituitary stalk to terminate on caps there When neuroendocrine cells stimulated to produce AP, release oxytocin/vasopressin into circulation

Question 36

hypothalamic releasing hormones and anterior pituitary

Answer 36

Anterior pituitary hormones controlled by overlying hypothalamus Hypothalamic neuroendocrine cells send axons to median eminence to secrete releasing hormones into hypophyseal portal system, which transports releasing hormones to pituitary Diff hypothalamic releasing hormones either stimulate/inhibit anterior pituitary cells that secrete tropic hormones

Question 37

the gonads produce steroid hormones, reg production

Answer 37

Hypothalamic cells secrete gonadotropin-releasing hormone (GnRH) into hypophyseal portal system to stimulate anterior pituitary cells to release follicle-stimulating hormone (FSH) and luteinising hormone (LH), which stimulates the gonads to release steroid hormones The principle gonadal steroids in males = androgens such as testosterone, while ovaries release oestrogen such as estradiol and progestins such as progesterone

Question 38

hormonal and neural systems interact to produce integrated responses

Answer 38

Many behaviours require coord of neural and hormonal components Messages may be transmitted in body via neural-neural, neural-endocrine, endocrine-endocrine/endocrine-neural links Experience affects hormone secretion, and hormones affect behaviour and therefore future experiences

Question 39

hormones are chemical messengers that are

Answer 39

Produced in endocrine cells Secreted into the bloodstream Transported by the bloodstream Act on specific target cells - typically some distance away from where produced

Question 40

Anterior pituitary/adenohypophysis

Answer 40

Synthesises and secretes hormones

Question 41

Posterior pituitary/neurophypophysis

Answer 41

Stores and secretes only (no synthesis)

Question 42

autocrine signal

Answer 42

acts upon cell that released it

Question 43

paracrine signal

Answer 43

act on nearby cells

Question 44

pheromones

Answer 44

chem signals to indvs of same species

Question 45

allomones

Answer 45

communicate with indvs of other species