The Endocrine System

Question 1

Where can organs of endocrine system mainly be found?

Answer 1

Neck 
Head 
Thoracic cavity 
Abdomen 
Pelvic cavity

Question 2

What two things can secrete hormones.

Answer 2

Organs

Glands

Question 3

Describe exocrine glands and examples

Answer 3

Exocrine glands have a duct and secrete products directly onto a surface or within a cavity through it

Examples: Salivary glands secrete saliva into mouth
Sweat glands secrete sweat onto skin surface

Question 4

Describe endocrine glands and examples.

Answer 4

Endocrine glands are ductless. They secrete their hormone into extra cellular fluid which diffuses into blood. It is then carried through blood to bind to a specific receptor on target cell or organ. This triggers a reaction.

Eg. Pituitary, adrenal and thyroid gland

Question 5

What organs can produce hormones

Answer 5

Pancreas
Liver
Heart

Question 6

Do hormones excite or inhibit

Answer 6

They excite or inhibit activity of other organs or tissues

Question 7

What hormones are produced by stomach?

Answer 7

Gastrin

Question 8

Hormones produced by small intestine:

Answer 8

Peptides
Secretin
Cholecystokinin

Question 9

Hormones produced by kidney

Answer 9

Erythropoietin
Renin
1,25- DHCC

Question 10

5 Main functions of the endocrine system

Answer 10

Balances sodium and water for blood volume
Balances calcium and phosphate levels to preserve extra cellular fluid for cell survival
Balances energy and controls macronutrients - proteins, carbohydrates and lipids and how they’re used and stored
Responses to stress
Reproduction, growth and development and sexual development

Question 11

What are categories of hormones

Answer 11

Non steroidal

Steroidal

Question 12

What do non steroidal hormones do?

Answer 12

They are one amino acid or short chain of amino acids. They bind to specific receptors on cell membrane, by lock and key.

Many chemical reactions happen once it has bind to activate molecules in the cell

These reactions are secondary messengers

Secondary messengers cause further reactions, secrete more hormones or secrete a different hormone

Question 13

What do steroidal hormones do?

Answer 13

Small, lipid soluble chemicals. Pass through cell membrane and easily through the cytoplasm.

They can enter nucleus of cell to bind to a receptor within the nucleus

Hormone-receptor complex formed

Complex causes DNA to do different things - eg, speed or slow cell processes, enable transport into cell or cell to secrete something else

Question 14

Which type of hormone is quicker response?

Answer 14

Non steroidal hormones act quicker than steroidal

Question 15

What are non steroidal hormones soluble in?

Answer 15

Soluble in water and insoluble in lipids

Question 16

What are the two types of non steroidal hormones?

Answer 16

Peptide or protein hormones

Amino - acid derived hormones

Question 17

Describe peptide or protein hormones

Answer 17

Most of non steroidal are this type

Vary in size (3-200 amino acids long)

They are synthesised as pre-prohormones first then undergo transformation to functioning hormone

Stored in secretory glands and exocytose from the cell

Examples: Insulin, glucagon and adrenocorticotropic hormones

Question 18

Amino acid derived

Answer 18

These proteins are synthesised from another amino acid

Commonly end in ‘ine’

Eg, adrenaline , noradrenaline and dopamine

Question 19

Steroidal hormones

Answer 19

Lipid soluble molecules

Derived from cholesterol and produced in adrenal cortex, gonads and placenta in women

Require binding proteins in the blood

Examples- Testosterone, oestrogen and progesterone

Question 20

5 Major pathways for hormones

Answer 20

PASEN

Paracrine- Cell produces and secretes a hormone and the hormone acts directly on nearby cell, eg, histamine and bradykinin

Autocrine- Cell produces and secretes hormone then the hormone binds to receptors on the cell membrane of the cell it came from, so these cells are secretory and receptive cells!

Synaptic pathway- Hormones produced in neurone, secreted and travels along axon to a synapse, where they are released and taken up by nearby neurone to exert effect.

Endocrine/ telocrine - hormone produced and secreted from cell, travels through blood and binds to distant cells at receptors

Neuroendocrine- Hormone produced in neurone, secreted, travels along axon to synapse, released and taken up into blood vessels to travel to cells with specific receptors

Question 21

Where are hypothalamus and pituitary gland?

Answer 21

Near each other at base of brain

Question 22

How do hypothalamus and pituitary gland interact?

Answer 22

Hypothalamus has neurones that produce inhibiting and releasing hormones to act on pituitary gland

Question 23

Give four common releasing hormones from hypothalamus

Answer 23

GHRH- Growth hormones releasing hormone
TRH- Thyrotropin releasing hormone
CRH- Corticotropin RH
GnRH- gonadotropin RH

Question 24

What does GHRH do?

Answer 24

Growth hormone RH released from hypothalamus and stimulates pituitary gland to produce growth hormone

Question 25

What does TRH do?

Answer 25

Thyrotropin RH released from hypothalamus and stimulates pituitary gland to produce thyroid stimulating hormone

Question 26

CRH?

Answer 26

Corticotropin RH comes from hypothalamus and stimulates pituitary gland to produce adenocorticotropic which releases cortisol in stress

Question 27

GnRH

Answer 27

Gonadotropin release hormone from hypothalamus stimulates pituitary gland to produce reproductive hormones

Question 28

What is the hormone known as that comes out of pituitary gland?

Answer 28

The TROPIC hormone

Question 29

What may trigger hypothalamus and pituitary gland to release hormones?

Answer 29

Neurotransmitters Injury Release of chemical mediators from injury Neuroendocrine signals They provide input to hypothalamus to regulate bodily functions Negative and positive feedback systems

Question 30

negative feedback loop

Answer 30

Most common mechanism Influenced by environmental and body temp, stress, nutrition and body substances Eg thyroid hormone or insulin in glucose regulation

Question 31

Example of negative feedback

Answer 31

Eating lots of carbohydrates - broken down to glucose Glucose levels rise Detected by beta cells in pancreas Stimulates release of insulin Insulin unlocks cells to absorb glucose As glucose enters cells, blood glucose decreases Pancreas stops producing insulin as it isn’t needed any more

Question 32

Positive feedback loop

Answer 32

Less common Amplify changes rather than reverse them Presence of hormone stimulates increased production of hormone until cycle is interrupted Eg oxytocin in childbirth

Question 33

Oxytocin

Answer 33

In birth, cervix is stretched and stimulates oxytocin release from hypothalamus More oxytocin means stronger and faster contractions Cervix stretched even more as more oxytocin produced and baby pushes Contractions stronger and faster until baby born Cervix no longer stretched Hypothalamus stops producing oxytocin

Question 34

Causes of altered hormone function

Answer 34

Impairment of pituitary gland or hypothalamus Impairment of endocrine glands Inactive hormone produced by gland Too much or too little hormone produced Inadequate hormone receptor binding Lack of response from target cell when hormone binds - lock and key does not work Impaired negative feedback loop Hormone produced in wrong place Impaired hormone metabolism and elimination

Question 35

What is acromegaly ?

Answer 35

Body produces too much growth hormone in adulthood Usually due to a benign tumour on pituitary gland Adults have large features so large hands and feet, enlarged tongue and prominent facials features Susceptible to carpal tunnel syndrome

Question 36

Gigantism

Answer 36

Body produces too much growth hormone during childhood Problem with pituitary gland, usually tumour Child appears large all over - very tall, large hands and feet and facial features. Prominent jaw and forehead.

Question 37

Achondroplasia/ dwarfism

Answer 37

Too little growth hormone produced from pituitary gland Short arms and legs and normal size torso Genetic disorder

Question 38

Name some other endocrine disorders

Answer 38

Hyperthyroidism (grave’s disease) Immune system will attack and damage thyroid gland cells Hypothyroidism (goitre, myxedema and developmental delay in children) Cushing syndrome Diabetes mellitus / insipidus Pheochromacytoma Glucagonoma Somatostatinoma

Question 39

What is thyroid like and what does it do?

Answer 39

Butterfly shape gland at anterior neck - shouldn’t be seen or able to palpate Critical role in metabolism Facilitates breakdown of proteins, carbohydrates and lipids for energy, stimulates heat and produces glucose Produces other structural proteins, enzymes or hormones Promotes growth and development in children mentally and physically

Question 40

Thyroid hormones

Answer 40

Thyrotropin RH comes from hypothalamus and stimulates thyroid hormone to produce thyroid stimulating hormone Thyroid stimulating hormone makes us release other thyroid hormones = T4= Thyroxine / tetraiodothyronine T3= Triiodothyronine Thyroid hormones also send signals to hypo and pituitary Issues with thyroid may have temperature or stress symptoms

Question 41

Thyroid hormones being released causes what? 10

Answer 41

Increased glucose absorption Increased oxygen consumption Increased cardiac output Release of lipids from adipose Increased cholesterol breakdown in liver Increased gastric motility Increased body heat production Metabolism of proteins from muscle tissue Increased muscle tone and reactivity Increased activation of cognitive processes

Question 42

Define hyperthyroidism

Answer 42

A disease where too many thyroid hormones are produced

Question 43

What causes hyperthyroidism?

Answer 43

Increased stimulation of thyroid gland Disease of thyroid gland Increased production of thyroid stimulating hormone by pituitary tumour Medications with high levels of iodine - eg cough medicine Health supplements or vitamins containing seaweed (high in iodine)

Question 44

Define hypothyroidism

Answer 44

Too little thyroid hormones produced from thyroid- congenital or acquired

Question 45

Describe congenital hypothyroidism

Answer 45

Occurs in foetal development There is lack of thyroid development so lack of thyroid hormones produced In Utero maternal T4 crosses placenta and baby appears normal at birth as they’ve grown and developed using mothers T4 Once cord is cut, there is gradual decline in growth and developmental delay as baby doesn’t produce own T4- has hypothyroidism Baby needs T4 supplement - sometimes picked up too late and can’t be given T4 as they’ve already missed brain development so is life shortening If detected by neonatal screening, or blood test, thyroid replacement treatment is given

Question 46

Graves’ disease

Answer 46

Auto immune disease causing excessive stimulation of thyroid gland 7-10 X more common in women than men They think it is caused by immunoglobulin antibodies that bind to TSH receptors on thyroid is too many thyroid hormones produced We get thyrotoxicosis= too many thyroid hormones in blood Symptoms: Enlarged thyroid gland (goitre so swelling anterior neck) Higher metabolic rate ``` Weight loss Agitation they can’t explain Sweating profusely Tachycardia Intolerant to heat Palpitations Tremor Fine hair everywhere Menstrual cycle problems Exophthalmos (bulging eyeballs) Weakness (as metabolism really high) ``` Treatment - quick treatment to prevent appearance like this Medication to stop thyroid hormone production Radio iodine treatment where radiotherapy destroys thyroid cells Surgery to remove part or all of thyroid Whole taken Away = supplements needed

Question 47

Acquired hypothyroidism

Answer 47

Thyroid gland doesn’t produce enough thyroid hormone ``` Due to: Autoimmune disorder Iodine deficiency Surgical removal of thyroid gland Radiotherapy to thyroid gland Medications that destroyed thyroid gland ``` 10 X common in women than men Treatment : lifelong replacement hormone treatment Eg, levothyroxine gives synthetic version of T4 Alleviation if clinical signs like constipation meds and fertility assistance ``` Symptoms: Fatigued / lethargic Cold all the time Weight gain Dry skin Coarse hair Constipation Reproduction - fertility problems Memory problems Goitre- thyroid trying to produce more hormones so increases in size Protein- carbohydrates disturbance so appear boggy Oedematous tissues like hand, feet and face Myxoedema Skin boggy and soft ```