Endocrine Physiology Flashcards
Hormones travel where to reach target organs/tissues?
Blood
If there is no receptor for tissues to detect hormones what happens?
No response
Neurotransmitters released from presynaptic neurons travel where?
Across Synaptic Cleft to Postsynaptic Cell to influence activity.
Neurotransmitters act where within synaptic cleft?
Locally
What happens when insulin targets skeletal muscle/adipose tissue?
Increase Glucose Uptake
What happens when insulin targets liver? (2)
Increased glycogenesis
Decreased Gluconeogenesis
Endocrine Hormones exert their effects at what concentration?
Very low concentrations (10-9 to 10-12)
Steroid hormones are derived from?
Cholesterol
Amine hormones are derived from
Tryptophan or Tyrosine
Peptide or Protein hormones are composed of
chains of amino acids
Name three types of Peptide Hormone
TRH
FSH
Insulin
Peptide hormones are synthesised as (2)
Preprohormone then cleaved into pro hormone
How are Peptide Hormones synthesised into preprohormone? (2)
Messenger RNA on ribosomes binds amino acids into peptide chain called preprohormone.
Chain is directed into ER lumen by signal sequence of amino acids
How are pro hormones created?
Enzymes in ER chop off signal sequence creating inactive pro hormone
Prohormones pass through where to get through Golgi complex
ER
What is the initial peptide hormone produced by ribosomes?
Preprohormone
What is cleaved off in endoplasmic reticulum to leave smaller but still inactive protein pro hormone?
Signal Sequence
What breaks down pro hormone into active hormone? (2)
Proteolytic Enzymes and Prohormone
What is the inactive fragment cleaved from insulin pro hormone?
C-Peptide
What is often measured in plasma or urine to indicate endogenous insulin production from pancreas?
C Peptide
What do Peptide hormones do in water?
Soluble so dissolve easily
What does water solubility mean for transport for peptide hormones across cell membranes
Cannot cross so have to bind to membrane bound receptors on target cells
Which receptors do most peptide hormones target (2)
GPCR or Tyrosine Kinase Linked Receptors.
What kind of response to peptide hormones on GPCR or Tyrosine Kinase Linked receptors get?
Fast (seconds/mins)
Peptide Hormones are said to be in terms of Hydro or Lipo?
Hydrophilic and Lipophobic
What do G protein Couple Receptors do? (2)
Activate 2nd Messenger System leading to modification of existing protein.
Rapid response
What do Tyrosine Kinase Linked Receptors do?
Alters gene expression.
Slow response
Which peptide linked receptor is slow response?
Tyrosine Kinase Linked Receptor
Amine hormones are mostly derived from?
Amino Acid Tyrosine
Name 3 Catecholamines?
Dopamine
Norepinephrine
Epinephrine
Which catecholamine is released from Adrenal Medulla?
Epinephrine
Thyroid Hormones are said to be what in terms of Lipo
Lipophilic like Steroid Hormones
Catecholamines are said to be what in terms of Hydro
Hydrophilic
What is the only amine hormone not derived from tyrosine?
Melatonin
Melatonin is derived from
Tryptophan
Melatonin regulates
Circadian Rhythm
Steroid hormones are derived from?
Lipids from cholesterol
Which hormone is synthesised directly as needed?
Steroid Hormones
What are steroid hormones in terms of lipo?
Lipophilic (Lipid Soluble)
How are steroid hormones transported?
Bound to Carrier Proteins such as Albumin
What is the half life of Steroid Hormones?
60-90 Mins
Half life of amine hormones?
2 mins
How long does steroid hormones action persist (2)
Slow Onset
Persists longer than Peptide or Amine Hormones
Steroid hormones are produced by? (4)
Gonads: Sex Steroids
Placenta: HcG, Sex Steroids
Kidney; Vit D3
Adrenal Cortex: Corticosteroid
Which steroid hormone vitamin does kidney produce?
D3
All steroid hormones are derived from?
Cholesterol
Which steroid hormones are made in adrenal cortex
Aldosterone and Cortisol
What allows steroid hormones to readily cross plasma membrane
Lipophilicity
Where are steroid hormones receptors found
Inside cells (cytoplasmic or nuclear receptors)
Activation of intracellular receptors for steroid hormones leads to?
Change in gene expression at level of nucleus (genomic effect)
Which part of steroid hormone can diffuse into target cell
Unbound hormone
Steroid hormone receptors are found where
Cytoplasm or nucleus
Which part of hormone can diffuse across capillary walls to target cells
Free Hormone
What is the equation for Total Plasma
Free Hormone + Complexed Hormone
What has poor solubility in Plasma?
Steroid/Thyroid Hormones
What is a specific carrier protein in plasma for steroid/thyroid hormone
corticosteroid binding globulin
What is a non specific carrier protein for steroid/thyroid hormones
Albumin
Carrier proteins do what for Steroid and Thyroid Hormones (2)
Increases Solubility
Protects from Degradation - Increased Half Life >60 Mins
As steroid hormone is taken up what happens?
More is released from carrier
Which part of steroid hormone crosses membrane
Unbound
Peptide and Catecholamine Hormones do what in water? (2)
Water Soluble and Transported in Plasma
Peptide and Catecholamines have what kind of half life in plasma
Short half life - usually mins
Steroid and Thyroid hormones half life?
Longer - usually hours to days
Hypothalamus is said to have what type of function?
Neuroendocrine
Any chemicals released into blood from hypothalamus are said to be ?
Neurohormones
Hypothalamus is connected to pituitary via?
Infundibulum Stalk
Hypothalamic Axons and Nerve Terminals project to?
Posterior Pituitary
Hypothalamus connection with anterior pituitary is via
neurohormones
How big is the Pituitary Gland?
14mm
Pituitary Gland is located where
Sphenoid Bone
Anterior Pituitary gland is connected to Hypothalamus via
Capillary Portal system
What is the origin of Anterior Pituitary?
Epithelial Origin
What is also called Adenohypophysis
Anterior Pituitary
Anterior Pituitary makes up how much of Pituitary Gland
2/3rds
Posterior Pituitary is a continuation of
Hypothalamus
Posterior Pituitary secretes
Neurohormones made in Hypothalamus
Posterior Pituitary is said to be
Neuroendocrine and Neural in Origin
Posterior Pituitary is also called
Neurohypophysis
Hypothalamus Functions (10)
Cold Stress Metabolic Demand Hydration Status Excess Menstrual Cycle Sleep Breastfeed Pregnancy Puberty
Pituitary Gland Functions (5)
Lactation Parturition Growth Water Balance Metabolism
Where releases Tropic and Non Tropic Hormones (2)
Hypothalamus and Ant Pituitary
All hormones released by Hypothalamus are
Neurohormones
All hormones released by Pos Pituitary are
Neurohormones
All hormones released by Ant Pitiuitary are
Endocrine Hormones
Non Tropic Hormones are produced where and travel where
Produced in Hypothalamus and Travel to Pos Pituitary via Axons of Hypothalamic Neurons where released into blood
Tropic Hormones are secreted into where and travel to where
Capillaries travelling to Ant Pituitary.
Posterior Pituitary contains what type of neurons?
Magnocellular Neurons
Magnocellular Neurons have cell bodies where
Hypothalamus
Magnocellular Neurons store and release what?
2 Peptide Neurohromones
- Vasopressin (ADH)
- Oxytocin
Vasopressin does what
Maintains Water balance
Oxytocin does what?
Stimulates uterine contraction and aids expression of milk
Which neurohormones does posterior pituitary release
Oxytocin and Vasopressin
Oxytocin and Vasopressin behave as
Typical Peptide Hormones
All hypothalamic neurohormones acting on ant pitiutary cells are
Tropic Hormones
What are the 5 Hypothalamic releasing hormones
TRH CRH GHRH GNRH PRH
What are the 2 Hypothalamic Inhibiting Hormones
GHIH aka Somatostatin
Dopamine aka Prolactin Inhibition’s Hormone
Which Hypothalamic releasing or inhibiting hormone is not a peptide
Dopamine
Dopamine is said to be a
Prolactin inhibiting hormone
The production of anterior pituitary hormones is controlled by
hypothalamic “releasing” or “inhibiting” tropic hormones that stimulate or inhibit hormone production from the anterior pituitary
What type of hormone are the 6 that are released from anterior pituitary gland
Peptides and Tropic
Name the 6 Ant Pituitary Hormones
Thyroid Stimulating Hormone aka Thyrotopin
Adrenocoritcotropic Hormone aka Corticotropin
Follicle Stimulating Hormone aka Gonadotropin
Lutenising Hormone
Growth Hormone
Prolactin
Which Anterior Pituitary Hormone is not Tropic?
Prolactin
What are the 3 integrating centres in Ant Pituitary Feedback control
hypothalamus
ant pituitary
target endocrine cells
feedback from endocrine target is what type of feedback
long loop feedback
feedback from ant pit to hypothalamus is what type of feedback
short loop feedback
Name an example of a short loop feedback
Ant Pit to Hypothalamus
Calcium released through Parathyroid to Bone and Kidney does what?
Increased Bone Resorption
Increased Kidney Reabsorption of Calcium
Production of Calcitrol leads to increased intestinal absorption of Ca2+
Leads to Increased Plasma Calcium
1st Degree Endocrine Disorders are what?
Defect is in cells that secrete hormone
2nd Degree Endocrine Disorders are what?
Those in which too little or too much tropic hormone from pituitary
3rd degree endocrine disorders are related to
Hypothalamic defects
What does permissive effects mean
Presence of one hormone enhances affect of another.
What does antagonist effects mean
presence of one hormone reduces effect of another.