Endocrine systems & hormones in animals Flashcards
Endocrine vs nervous system
*Nervous system
Neurotransmitters
Rapid (~100m/s)
Targeted
All-or-nothing
*Endocrine system
Hormones (“setting in motion”)
Slower (s, mins, hrs)
Large spatial area
Graded response
What do hormones do?
Regulate exocrine/endocrine gland secretions
Regulate growth and development
Control reproductive processes
Coordinate response to environmental stimuli
What are;
Glucocorticoid hormones (slighlty different structure)
Catecholamines (refers to structure of the molecule)
Adrenaline/Noradrenaline
Glucocorticoid hormones = cortisol/corticosterone
Catecholamines = Adrenaline/Noradrenaline
Adrenaline/Noradrenaline = Epinephrine/Norepinephrine
Describe some functions of insect hormones?
Juvenile hormone (in haemolymph)
Juvenile characteristics
Inhibition triggers metamorphosis
Reproductive maturity in adults
Yolk/seminal fluid production
What do these do (insects)?
Prothoracicotrophic (PTTH)
Edysone
Eclosion
Burcison
Prothoracicotrophic (PTTH): stimulates ecdysone production
Edysone: production of new cuticle
Eclosion: new cuticle
Burcison: tanning of new cuticle
HPG axis
what do these do;
*Gonadotropin-releasing hormone (GnRH)
*Follicle-stimulating hormone
*Lutenizing hormone
*Gonadotropin-releasing hormone (GnRH) produced in the hypothalamus
-Stimulates gonadotropin (FSH/LH) release
*Follicle-stimulating hormone
-Maturation of germ cells, i.e. follicular growth, spermatogenesis
*Lutenizing hormone made in pituitary gland
-Estrodiol/testosterone production
-Reproductive tissues
-Behaviour
-Negative feedback
What are the methods for studying hormones?
Correlatively
Exposure
Inhibitors
By removing/transplanting glands
Vertebrate hormones explain water soluble and lipid soluble
*Water soluble
Travel on circulatory system
Bind to surface receptors
Cascade –>signal transduction
Altered transcription
*Lipid-soluble
Need carrier proteins
Bind to receptors on surface or in nucleus
Vertebrate nervous system
PNS (peripheral nervous system)
Afferent (sensory): PNS–> CNS
Efferent (motor): CNS –>PNS
Divisions
Somatic nervous system: voluntary and reflex movements of skeletal muscles
-Acetylcholine (cholinergic)
Autonomic nervous system:
Sympathetic (mostly adrenergic, catecholamines)
-Parasympathetic (cholinergic)
Explain the autonomic nervous system
Negative feedback –>homeostasis
Control centre: hypothalamus
Parasympathetic= Feed & Breed”, “Rest & Digest”
Slowly activated dampening
-Conserves energy (e.g. heart)
Sympathetic
“fight-or-flight”
Quick response mobilising
-Mobilises energy (e.g. heart)
Direct effects of the autonomic nervous system
sympathetic
Skeletal muscles=“no” vessel vasoconstriction
Gastro-intestinal tract= Vasoconstriction; constrict sphincters; inhibit peristalsis
Periphery=Vasoconstriction
Lungs=Dilate bronchioles, vasodilation
Heart=Coronary vessel dilation; Increase contraction
Eyes=Relaxes ciliary muscles for pupil dilation
Glands=Altered hormone secretion: metabolism versus other functions!
Direct effects of the autonomic nervous system
parasympathetic
Skeletal muscles= Vasodilation; Stimulates salivary gland; accelerates peristalsis
Gastro-intestinal tract= Vasodilation
Lungs= Constrict bronchiolar diameter
Heart= Baseline contraction
Eyes= Constriction/contraction of ciliary muscles
Glands= Altered hormone secretion: metabolism versus other functions!
HPA axis and the SAM pathway
Hypothalamic-Pituitary-Adrenal axis
Sympathomedullary (‘sympathoadrenal’) Pathway
(neuroendocrine) Hypothalamus is the control centre
1. (hormone)Corticotropin-releasing hormone
(CRH) hypothalamus –> Pituitary
2. Adrenocorticotropic hormone (ACTH) pituitary adrenal gland
–>ACTH stimulates adrenal glands to produce cortisol/corticosterone
Neuroendocrine cells produce catecholamines
3. (hormonal) Negative feedback: circulating corticosteroids detected by receptors in the hypothalamus
Describe the pituitary gland
Pea-sized gland!
Human growth hormone (GH)
Thyroid-stimulating hormone (TSH)
-thyroxine in thyroid
-baseline metabolic rate
Luteinizing hormone (LH) and Follicle-stimulating hormone)
-regulates reproductive system
Prolactin
-lactation, regulates reproduction
Adrenocorticotropic hormone (ACTH)
Adrenal Gland
*Steroidogenesis
Mineralocorticoids (e.g. aldosterone)
–>blood pressure/electrolyte balance
Glucocorticoids (cortisol/corticosterone)
–>metabolism/altered immune function
*Androgens
-converted to sex hormones in gonads
-reproductive function
*Chromaffin cells
“Neuroendocrine cells” “post-ganglionic”
Epinephrine and norepinephrine
Similar structure to nerve cell, but exocytosis directly into blood stream = neurohormone
