Coordination and Control: Endocrine System Flashcards by Angharad Jones

Functions of the Endocrine System

Cell communication
a control system - with nervous system - controls other parts of the body
Controls all major body processes

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What is the endocrine system made up of?

a collection of endocrine glands and tissues and their hormone products

Many blood vessels - highly vascularised

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Endocrine definition

= Internal secretion

Hormones secreted directly into the bloodstream

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Exocrine glands

= External secretion

Hormones secreted into ducts

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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

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List 7 major endocrine glands

Thyroid gland
Para - thyroid gland
Ovary
Testes
Pituitary gland
Adrenal gland
Pancreas

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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

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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

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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

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Thyroid Gland
Hormone Products and function

Products - Thyroxine, Calcitonin

Function - Thyroxine -> role in heart and
digestive function
Calcitonin -> regulates blood calcium
levels

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Parathyroid gland
Hormone Products and function

Products - Parathyroid hormone (PTH)

Function - helps maintain calcium balance in blood and tissues

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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

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Pancreas
Hormone Products and function

Products - Glucagon, Insulin

Function - Glucagon -> controls blood glucose
levels
Insulin -> allows muscle, fat and liver
cells to absorb glucose

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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

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4 Modes of hormone action

Paracrine
Autocrine
Endocrine
Neuro - endocrine

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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

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What are the 5 steroid hormones?

Progestogens
Glucocorticoids
Mineralocorticoids
Androgens
Oestrogens

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What are some non-steroid Polypeptide / Protein hormones?

Growth hormone,
Prolactin,
Calcitonin,
Parathyroid hormone,
Adrenocorticotrophic hormone (ACTH),
Insulin,
Glucagon

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What are 4 non-steroid glycoprotein hormones?

FSH
LH
TSH
Human Chorionic Gonadotropin (hCG)

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What are 3 non-steroid Eicosanoid hormones?

Prostaglandins
Leukotrienes
Prostacyclins

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What are some non-steroid peptide hormones?

ADH
Oxytocin,
Melanocyte stimulating hormone
Somatostatin
Thyrotrophin-releasing hormone
Gonadotrophin-releasing hormone

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What are some non - steroid amines hormones?

Adrenaline
Noradrenaline
Melatonin
Thyroxine T4
Tri-iodothyronine T3

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Why do glycoproteins have a longer lasting actoin

Glycoproteins are glycosylated so have longer lasting action

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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

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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