Coordination and Control: Endocrine System Flashcards
Functions of the Endocrine System
- Cell communication
- a control system - with nervous system - controls other parts of the body
- Controls all major body processes
What is the endocrine system made up of?
a collection of endocrine glands and tissues and their hormone products
Many blood vessels - highly vascularised
Endocrine definition
= Internal secretion
Hormones secreted directly into the bloodstream
Exocrine glands
= External secretion
Hormones secreted into ducts
What are the 3 endocrine tissues?
- Endocrine organ devoted to hormone synthesis e.g. thyroid gland
- Distinct clusters of cells within organ e.g. islets of Langerhans (pancreas)
- Individual cells scattered diffusely throughout organ e.g. gastrointestinal tract, skin
List 7 major endocrine glands
Thyroid gland
Para - thyroid gland
Ovary
Testes
Pituitary gland
Adrenal gland
Pancreas
Hypothalamus -
Hormone Products and function
Products - Releasing hormones + inhibiting factors e.g. growth hormone releasing hormone (GHRH)
Function - stimulates every body tissue to control metabolism and grow
Posterior pituitary -
Hormone Products and function
Products - Anti - diuretic hormone (ADH), Oxytocin
Function - ADH -> helps blood vessels constrict and kidneys control amount of water and salt in body
Oxytocin - stimulates contractions and milk flow
Anterior Pituitary -
Hormone Products and function
Products - Growth hormone, Follicle stimulating hormone (FSH), Luteinising hormone (LH)
Function - FSH -> helps control mensural cycle,
egg production
LH -> important role in sexual
development
Thyroid Gland
Hormone Products and function
Products - Thyroxine, Calcitonin
Function - Thyroxine -> role in heart and
digestive function
Calcitonin -> regulates blood calcium
levels
Parathyroid gland
Hormone Products and function
Products - Parathyroid hormone (PTH)
Function - helps maintain calcium balance in blood and tissues
Adrenal gland
Hormone Products and function
Products - Adrenaline, Cortisol
Function - Adrenaline -> body’s fight or flight
response
Cortisol -> primary stress hormone,
increases sugars in the
bloodstream
Pancreas
Hormone Products and function
Products - Glucagon, Insulin
Function - Glucagon -> controls blood glucose
levels
Insulin -> allows muscle, fat and liver
cells to absorb glucose
Gonads
Hormone Products and function
Products - Progesterone, Oestrogen,
Testosterone
Function - Progesterone -> prepares
endometrium for potential
pregnancy after ovulation
Oestrogen -> regulates growth and
development of
reproductive system
Testosterone -> regulates sex drive,
muscle mass and strength
4 Modes of hormone action
Paracrine
Autocrine
Endocrine
Neuro - endocrine
What is the chemical nature of hormones related to?
- How they are synthesised & secreted
- Nature of hormone receptor they bind to
- Ability to bind to other proteins (eg. transport
proteins - How they partition in tissues
- How they are degraded
What are the 5 steroid hormones?
Progestogens
Glucocorticoids
Mineralocorticoids
Androgens
Oestrogens
What are some non-steroid Polypeptide / Protein hormones?
Growth hormone,
Prolactin,
Calcitonin,
Parathyroid hormone,
Adrenocorticotrophic hormone (ACTH),
Insulin,
Glucagon
What are 4 non-steroid glycoprotein hormones?
FSH
LH
TSH
Human Chorionic Gonadotropin (hCG)
What are 3 non-steroid Eicosanoid hormones?
Prostaglandins
Leukotrienes
Prostacyclins
What are some non-steroid peptide hormones?
ADH
Oxytocin,
Melanocyte stimulating hormone
Somatostatin
Thyrotrophin-releasing hormone
Gonadotrophin-releasing hormone
What are some non - steroid amines hormones?
Adrenaline
Noradrenaline
Melatonin
Thyroxine T4
Tri-iodothyronine T3
Why do glycoproteins have a longer lasting actoin
Glycoproteins are glycosylated so have longer lasting action
peptide hormones key facts
Peptide:
- Structure = Chains of amino acids
- Solubility = Hydrophilic
- Synthesis = Gene transcription and post translational modification in Golgi
- Storage = Large amounts in secretory granules
- Secretion = Exocytosis
- Transport = as free hormone
- Cell surface receptor
- Mechanism of action = Activation of second messenger system to alter activity of existing proteins
Steroid hormones key facts
Steroid
-Structure = Cholesterol - derived
- Solubility = Lipophilic
- Synthesis = De novo biosynthesis ( stepwise modification of cholesterol in mitochondria and SER)
- Storage = Not stored
- Secretion = Simple diffusion
- Transport = bound to transport proteins
- Intracellular receptor
- Mechanism of action = Activation of specific genes to produce new proteins
Actions of hormones
- present in blood in very low conc
- widespread
- slower acting than neurotransmitters
- can be transported over long distances
- require specific receptors
- long lasting ( permanent) effects
What factors determine the response of hormones?
- Concentration of hormones
- Number of receptors on target cells
- Affinity of hormone receptors
- Duration of exposure
What can hormones alter within cells?
Contraction and relaxation of muscles
Release of hormones and nerve signals
Transcription of genetic information
Synthesis of proteins
Cell shape and motility
Protein phosphorylation alters protein function
What are the 3 main causes of endocrine disorders?
Hormone deficiency
Hormone excess
Hormone resistance
How can hormone deficiency cause endocrine disorders?
Destruction of gland
Extraglandular disorder
Defect in biosynthesis
How can hormone excess cause endocrine disorders?
Tumours of endocrine gland
Ectopic hormone production
Overstimulation (hyperplasia)
Exogenous hormone
How can hormone resistance cause endocrine disorders?
Receptor defects
What is the hypothalamus - pituitary axis
the interface between central nervous system and endocrine system
What does the hypothalamus - pituitary axis control?
The neuroendocrine control and homeostatic regulation of:
- Stress & immune function
- Reproduction
- Growth and development
- Water/electrolyte balance
- Energy balance/appetite control
- Thermoregulation
- Sleep/wakefulness
Homeostasis definition
Achieving stability through change
Where is the hypothalamus located?
In the basal forebrain close to ‘optic chiasm’
Hypothalamus function
Involved in pituitary regulation
Hypothalamic neurosecretory cells (modified neurones) release peptides from axon terminals near to capillaries
Peptides include ‘releasing hormones’ –which regulate anterior pituitary and two posterior pituitary hormones
What are the two glands in the pituitary called?
Posterior Lobe (neurohypophysis)
and
Anterior lobe (adenohypophysis)
What type of control is the Posterior Lobe (neurohypophysis) under
under DIRECT control
What type of control is the Anterior Lobe (adenohypophysis) under
under INDIRECT control
What is the Posterior Lobe
Neural tissue comprising of axons and nerve terminal endings of hypothalamic neurosecretory cells
What is the Anterior Lobe
Glandular tissue comprising of cells controlled by releasing hormones (or inhibitory factors) delivered via hypophysial portal system
What are two posterior pituitary hormones?
ADH (in kidneys )and oxytocin
How is posterior pituitary blood supply controlled and regulated?
Blood supply from inferior/middle hypophsial arteries
DIRECT innervation from hypothalamus axons from pituitary stalk, release neurohypophysial hormones into systemic blood
How is anterior pituitary blood supply controlled and regulated?
Blood supply from pituitary portal system
No direct innervation but parvocellular neurones terminate in median eminence of hypothalamus and release hypophysiotrophic hormones into portal blood supply
Name the 2 posterior pituitary hormones secreted from the posterior lobe of the pituitary gland
Oxytocin
Anti-diuretic hormone (ADH)
Name the 4 anterior pituitary hormones with tropic action secreted from the anterior lobe of the pituitary gland
Follicle stimulating hormone (FSH)
Luteinising hormone (LH)
Adrenocorticotrophic hormone (ACTH)
Thyroid stimulating hormone (TSH)
Name the 2 other anterior pituitary hormones secreted from the anterior lobe of the pituitary gland
Growth hormone
Prolactin
Name the all 8 hormones secreted by the pituitary gland
Oxytocin
Arginine-vasopressin (ADH)
Follicle stimulating hormone (FSH)
Luteinising hormone (LH)
Adrenocorticotrophic hormone (ACTH)
Thyroid stimulating hormone (TSH)
Growth hormone
Prolactin
What neuroendocrine system is prominent in the control of major glands including Thyroid gland, Adrenal gland, Gonads (ovary/testis)
Tripartite
How does the tripartite neuroendocrine system work?
Releasing hormone –> tropic hormone –> Hormone
How does feedback control work?
Feedforward drives increased hormone output and hormone negative feedback
Hormone levels fluctuate and can be influenced by biorhythms
Name some common endocrine problems
Type 1 diabetes, Obesity, Thyroid disorders
- often caused by too little or too much hormone being released, or a problem with its hormone receptor
What is the role of Thyroxine?
regulation of cell metabolism
What is the role of Prolactin?
Milk production and fertility control
What is the role of Growth hormone?
Overall body size and growth of tissues
What is the role of cortisol?
Stress adaptation and suppression of inflammation
What is the role of insulin?
blood glucose regulation
What is the role of Oxytocin?
Milk ejection and contraction of uterus during labour
What is the role of testosterone?
Regulates sex drive and muscle mass and strength.
What is the role of adrenaline?
Fight or fight response
What is the role of oestrogen?
Growth and development of reproductive system
