The Pituitary Gland Flashcards by Annie Caldwell

What are the principal organisers of the endocrine system?

The hypothalamus and the pituitary

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What is the hypothalamus a part of and what is it found underneath?

The brain

Under the thalamus

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How is the hypothalamus connected to the pituitary gland?

Via a stalk - the infundibulum

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Type of communication between hypothalamus and posterior pituitary

Neural

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Type of communication between the hypothalamus and the anterior pituitary

Endocrine

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What type of function is hypothalamic communication?

Neuroendocrine

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What type of tissue is the hypothalamus?

Nervous tissue

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Two functions of the hypothalamus

Releases neuroendocrine hormones from the posterior pituitary gland
Causes the anterior pituitary gland to release hormones

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What bone is the pituitary gland found in?

Sphenoid bone

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Two parts of the pituitary gland

Anterior pituitary

Posterior pituitary

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What is the posterior pituitary a continuation of?

Neural tissue from the hypothalamus

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What is the anterior pituitary?

A true endocrine gland of epithelial origin

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What can cause effects on the hypothalamus?

Cold
Stress
Metabolic demand 
Hydration status
Exercise 
Day / night 
Menstrual cycle
Sleep 
Breastfeeding 
Pregnancy 
Puberty

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Function of trophic hormones

Govern the release of another hormone

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What kind of hormones does the hypothalamus release?

Neurohormones

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Where are neurohormones released into?

The blood

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What type of hormones does the posterior pituitary release and why?

Neurohormones

Because it is a continuation of the hypothalamus

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What is the posterior pituitary?

A mass of nerves and axon terminals that start in the hypothalamus

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What type of hormones are released from anterior pituitary?

Endocrine hormones

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Two forms of hypothalamic neurohormones

Trophic

Non-trophic

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What are trophic hormones?

Neurohormones secreted into capillaries travelling to the anterior pituitary which then govern the release of anterior pituitary hormones

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What are non-trophic hormones?

Neurohormones produced in the hypothalamus and travel to posterior pituitary (via axons of hypothalamic neurones) where they are released into the blood

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Only what kind of hormones go to the anterior pituitary?

Trophic hormones

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How is the anterior pituitary connected to the hypothalamus?

Via a capillary portal system

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Another name for the anterior pituitary

Adenohypophysis

How much of the gland does the anterior pituitary make up of the gland?

2/3rds of the gland

Another name for the posterior pituitary

Neurohypophysis

How much of the gland does the posterior pituitary make up?

1/3rd

Function of hypothalamic trophic hormones

Bind to receptors on anterior pituitary and stimulate or inhibit the release of AP hormones

What are the 5 hypothalamic releasing hormones?

``` Thyrotrophin releasing hormone (TRH) Corticotrophin releasing hormone (CRH) Growth hormone releasing hormone (GHRH) Gonadotrophin releasing hormone (GnRH) Prolactin releasing hormone (PRH) ```

What are the 2 hypothalamic inhibiting hormones?

Growth Hormone Inhibiting Hormone (GHIH) | Dopamine

What is GHIH also known as?

Somatostatin

What is dopamine also known as?

Prolactin inhibiting hormone (PIH)

What kind of hormones are all of the hypothalamic hormones to the anterior pituitary, except from dopamine?

Peptide hormones

What kind of hormone is dopamine?

An amine hormone

What is the hypothalamo-hypophyseal portal system?

Network of tiny vessels which transfer trophic hormones from the hypothalamus to anterior pituitary

Where are hormones released from neurosecretory neurones in the hypothalamo-hypophyseal system?

At the median eminence

How far is the portal system for the hormones to travel and therefore what does this mean?

Not a far distance and therefore very rapid and dynamic

How is the anterior pituitary attached to the hypothalamus?

Via the hypothalamic-hypophyseal portal system (two capillary beds connected in series)

What are the 6 anterior pituitary hormones?

``` Thyroid stimulating hormone (TSH) Adrenocorticotrophic Hormone (ACTH) Follicle stimulating hormone (FSH) Leuteinising hormone (LH0 Growth Hormone (GH) Prolactin ```

Another name for TSH

Thyrotrophin

Another name for ACTH

Corticotrophin

What are the gonadotrophins?

FSH | LH

Function of prolactin

Directly stimulates milk production from the breast during lactation

Target of prolactin

Mammary glands

Target of TSH

Thyroid gland

Target of ACTH

Adrenal cortex

Targets of gonadotrophins

Ovary and testis

Function of ACTH on the adrenal cortex

Cortisol release

Function of growth hormone

IGF-1 release from the liver (trophic) | Tissue metabolism

Function of gonadotrophins

Regulation of reproductive function (Direct) | Sex hormone release (trophic)

What 3 integration centres does anterior pituitary feedback control involve?

Hypothalamus Anterior pituitary Target endocrine cell

In anterior pituitary feedback control, what acts as a negative feedback signal?

Hormones themselves

What does long loop feedback involve?

Feedback from endocrine target

What does short loop feedback involve?

Anterior pituitary to hypothalamus

What does the posterior pituitary store and release?

2 peptide hormones - vasopressin - oxytocin

Another name for vasopressin

ADH

What type of neurones in the hypothalamus are posterior pituitary hormones synthesised in?

Magnocelular neurones

How do the axons that project down the infundibulum to the posterior pituitary end?

They do not synapse with other neurones | Their terminals end directly on capillaries

What type of hormones are oxytocin and vasopressin?

Peptide hormones

Main function of ADH/vasopressin

Regulates water balance

What is the release of ADH/vasopressin triggered by?

Increase in plasma osmolarity | Decrease in plasma volume / blood pressure

How does ADH/Vasopressin work?

Kidney collecting ducts - increased water reabsorption | Vascular smooth muscle effects to increase blood pressure

Main functions of oxytocin

Milk ejection and uterine contraction during childbirth

Definition of hyposecretion

Too little hormone secreted

Definition of hypersecretion

Too much hormone secreted

Definition of hyporesponsiveness

Reduced response of target cell

Definition of hyperresponsiveness

Increased response of target cell

Definition of primary endocrine disorder

those in which the defect is in the cells that secrete the hormone

Definition of secondary endocrine disorder

Those in which there is too little or too much trophic hormone from pituitary

Definition of tertiary endocrine disorder

Relate to hypothalamic defects (relatively rare)