Glands and Hormones Flashcards by Michaela Netto

What are the 2 parts of the pituitary gland?

Anterior pituitary (adenohypophysis) 
Posterior pituitary (neurohypophysis)

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What are the roles of the hypothalamus?

Thermoregulation 
Hormone secretion 
Circadian rhythms 
Motivation 
Emotions

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What happens to the body when it is cold?

Cold temperature -> drop in body temperature
Sends signals to thermoreceptors in the hypothalamus
Compares with ‘set point’
Effectors generate an effect: increase heat production and decrease heat loss - shivering, vasoconstriction

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When is body temperature at its lowest?

When you sleep

Body temperature is controlled by the circadian rhythm

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Set body temperature is not constant. What happens to set body temperature after eating a meal?

Set body temperature increases

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The hypothalamus produces releasing hormones. What do these hormones act on?

The anterior pituitary
Pass to the AP via blood vessels - hypothalamic-pituitary portal vessels
They trigger secretion of hormones from the anterior pituitary

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How do hormones travel from the hypothalamus to the posterior pituitary?

Along nerve axons

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Give some examples of hypothalamic hormones

Corticotropin releasing hormone (CRH) 
Gonadotrophin releasing hormone (GRH)
Thyrotropin releasing hormone (TRH)
Growth hormone releasing hormone (GHRH)
Somatostatin (SS)
Prolactin releasing hormone (PLRH)
Dopamine (DA)

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Give some examples of anterior pituitary hormones

Adrenocoritoctropic hormone (ACTH) 
Follicle stimulating hormone (FSH)
Luteinising hormone (LH)
Thyroid stimulating hormone (TSH)
Growth hormone (GH)
Prolactin (PL)

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Which nuclei of the hypothalamus send their axons down to the posterior pituitary?

Supraoptic nucleus and paraventricular nucleus

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Describe the HPA axis

Stressor detected by the hypothalamus, releases CRH
CRH acts on anterior pituitary, releases ACTH
ACTH acts on the adrenal cortex, releases cortisol
Cortisol has negative feedback action on the hypothalamus and anterior pituitary (suppresses its own release)

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Describe the chain of events that lead to the production of FSH and LH

Stimulus on hypothalamus, releases gonadotropin releasing hormone (GRH)
GRH acts on anterior pituitary, which releases follicle stimulating hormone (FSH) and luteinising hormone (LH)
Females: FSH causes ovum maturation and progesterone production. LH causes ovulation and production of oestrogen and progesterone
Males: FSH causes sperm production, LH causes testosterone production

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Which hormones are produced by neurons in the hypothalamus and pass to the posterior part of the pituitary?

Oxytocin and vasopressin (ADH)

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Which target organ does ADH act on?

The kidney: results in water reabsorption in the collecting ducts

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Describe the role of oxytocin in parturition

Stretch of uterus -> hypothalamus detects this stretch and responds by releasing oxytocin via axons
Oxytocin passes to posterior pituitary and is released into plasma
Results in contraction of the uterus

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Describe the role of oxytocin in milk ejection

Infant suckling stimulates the hypothalamus
Oxytocin is transmitted to the posterior pituitary gland via axons
Oxytocin is released into plasma and cause milk ejection

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Where is the thyroid gland located?

In the neck, anterior to the trachea

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Which hormones are produced by the thyroid gland?

tri-iodo-thyronine (T3), tetra-iodo-thyronine (T4/thyroxine) - produced by cells around the follicles
Calcitonin - produced by parafollicular C cells

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What is the precursor for the thyroid hormone T3?

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What are the actions of T3 and T4 hormones? (thyroid hormones)

Increase metabolic rate of cells
Determines basal metabolic rate
Essential for normal foetal and childhood growth
Permissive effect on action of adrenaline by up-regulating adrenoreceptors

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What are some of the disorders of thyroid hormones?

Undersecretion: Hypothyroidism, Cretinism, myxoedema

Oversecretion: Hyperthyroidism, Grave’s disease

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How can hypothyroidism in adults be treated?

With thyroxine (T4) hormones

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What is goitre?

Thyroid swelling associated with iodine deficiency

Low levels of thyroxine result in increased secretion of TSH

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What is exopthalmos and what can it be caused by?

Bulging of the eyes anteriorly out of the socket

Can be associated with over secretion of thyroid hormones

How many parathyroid glands are in the human body and where are they located?

4-5 pea sized parathyroid glands lie on the deep surface of the thyroid gland

What do parathyroid glands produce?

Parathyroid hormones - involved in the regulation of blood calcium levels

What percentage of the pancreas accounts the endocrine portion?

``` 1-2% = endocrine ~99% = exocrine ```

Which hormones are produced by Islet of Langerhans cells?

Insulin (beta cells) Glucagon (alpha cells) Somatostatin (delta cells)

What does the exocrine portion of the pancreas produce?

Enzymes

When is insulin released?

In response to: high blood glucose levels, raised amino acid levels, glucose-dependent insulinotropic peptide, vagus nerve

What is insulin secretion inhibited by?

Adrenaline Sympathetic nerves Somatostatin

What are the effects of insulin on the body?

Acts to lower blood glucose Facilitates glucose entry into muscle cells, adipocytes Promotes formation of glycogen and triglycerides and facilitate protein synthesis

When is glucagon released?

In response to low blood glucose concentration

What does glucagon do?

``` Acts to raise blood glucose concentration Actions include: Glycogenolysis in liver Gluconeogenesis in liver Lipolysis and ketone synthesis ```

What promotes the secretion of glucagon?

Decreased blood glucose Increased blood amino acids Cholecystokinin (CCK) Autonomic nerve activity

What inhibits the secretion of glucagon?

Insulin | Somatostatin

Describe diabetes mellitus

Diabetes means "increase in urine" Elevated blood glucose concentration Decreased glucose uptake by cells Metabolic changes: gluconeogenesis, lipolysis

What are the clinical features of diabetes mellitus?

``` Polyuria Polydipsia Glucosuria Diabetic neuropathy Skin and oral diseases incl. xerostomia and periodontitis ```

What is the different between Type 1 and Type 2 Diabetes Mellitus?

Type 1 = insulin dependent. Accounts for 10% of cases. Decreased insulin secretion. Destruction of beta cells. Early onset. Treatment = insulin injections and diet Type 2 = insulin independent. Insulin levels are "normal". Target cells not responding to insulin. Related to being overweight/obesity. "Late" onset. Treatment = diet, oral hypoglycaemia agents.

Where are the adrenal glands located?

On top of the kidneys

Which hormones are produced by the adrenal cortex?

Cortisol, aldosterone and androgens (corticosteroids)

Which hormones are produced by the adrenal medulla?

Adrenaline and noradrenaline

What are the 3 parts of the adrenal cortex and which hormones does each part produce?

Zona glomerulosa: aldosterone Zona fasciculata: cortisol and androgens Zone reticularis: androgens

What type of hormone is cortisol?

A glucocorticoid

Where is cortisol produced?

The zona fasciculata of the adrenal cortex

What are the effects of cortisol?

Metabolic effects Permissive effects Anti-inflammatory Immunosuppressant

What type of hormone is aldosterone?

A mineralocorticoid

Where is aldosterone produced?

The zona glomerulosa of the adrenal cortex

What is the release of aldosterone controlled by?

The renin-angiotensin-aldosterone system (RAAS)

What are the actions of aldosterone?

Promotes reabsorption of sodium and water in kidneys (DCT) | Increases secretion of H+ and K+

Describe the RAAS system

Angiotensinogen is converted to angiotensin I by renin Angiotensin I is converted to Angiotensin II by ACE (angiotensin converting enzyme) Angiotensin II acts on adrenal cortex Aldolsterone is released

What type of hormone are androgens?

Gonadocorticoids

Where are androgens produced

Zona fasciculata and zone reticularis of the adrenal cortex

What do androgens do in the human body?

Contribute to growth and secondary sexual characteristics | Pubertal growth spurt

What is Cushing's syndrome?

A disorder caused by excess glucocorticoids | Features include: moon face, fat pads, thin skin, poor muscle development, poor wound healing, pendulous abdomen

What is Adreno-genital syndrome?

A disorder caused by excess androgens | Features include: hirsutism, baldness, brest development, heavy arms and legs

What is the adrenal medulla?

A modified sympathetic ganglion controlled by pre-ganglionic sympathetic nerves The cells mostly produce adrenaline Adrenaline release augments the action of the sympathetic nervous system

What is Addison's disease?

A disease caused by adrenal insufficiency Decreased adrenal function and reduced levels of adrenal hormones (glucocorticoids, mineralocorticoids) Very serious condition