Endocrine System Flashcards by Courtney @Brainscape

Q

Main Types of Hormones

Insulin and parathormone are examples of

A

Protein and glycoprotein hormones

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Q

Main Types of Hormones

Vasopressin and Oxytocin are examples of

A

Small peptide hormones

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Q

Main Types of Hormones

Thyroxin and Adrenalin are examples of

A

Hormones that are derivatives of amino acids

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Q

Main Types of Hormones

Testosterone and Cortisol are examples of

A

Steroids derived from cholesterol

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Q

Components of Endocrine System

Major endocrine organs

A

Principal or only role of organ is hormone production (thyroid, adrenal gland)

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Q

Components of Endocrine System

Organs with partial but significant endocrine role

A

Such as pancreas, ovary or testes

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Q

Components of Endocrine System

Diffuse endocrine system

A

Scattered cells within organs performing endocrine function, such as enteroendocrine cells of the gut working on nearby cells (paracrine)

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Q

Endocrine Tissue

Most is of what origin?

A

Epithelial

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Q

Endocrine Glands

A

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Q

Pitutary Gland

Able to regulate

A

Many other endocrine glands

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Q

Pitutary Gland

Location

A

In the sella turcica of the sphenoid bone, just below the hypothalamus

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Q

Pitutary Gland

Also called

A

Hypophysis

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Q

Hypothalmic-Pituitary Axis

A

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Q

Pituitary Gland

Two Lobes

A

Anterior lobe (adenohypophysis) and posterior lobe (Neurohypophysis)

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Q

Pituitary Hormone Secretion

Anterior Lobe

A

Controlled by hormones from the hypothalamus entering in high concentrations through the hypothalamic-hypophyseal portal system

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Q

Hypothalamic Hormones

Regulating anterior pituitary

A

GHRH, Somatostatin, TRH, CRH, Dopamine, GnRH

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Q

Anterior Pituitary Cell Types

Somatotrophs

A

Produce GH and controlled by GHRH(+) and Somatostatin (-)

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Q

Anterior Pituitary Cell Types

Thyrotrophs

A

Produce TSH and regulated by TRH(+) and Somatostatin(-)

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Q

Anterior Pituitary Cell Types

Corticotrophs

A

Produce ACTH and controlled by CRH

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Q

Anterior Pituitary Cell Types

Lactotrophs

A

Produce Prolactin and controlled by TRH(+) and Dopamine(-)

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Q

Anterior Pituitary Cell Types

Gonadotrophs

A

Produce FSH and LH, and controlled by GnRH

Q

Anterior Pituitary

Consists of

A

Packed secretory cells interspersed with fenestrated edothelium-lined vascular sinuses

Q

Anterior Pituitary

Acidophils and Basophils

A

Acidophils: Somatotrophs and lactotrophs

Basophils: Thyrotrophs, corticotrophs and gonadotrophs

Q

Posterior Pituitary

Consists of

A

The axons of nerve cells in the supraoptic and paraventricular nuclei of the hypthalamus

**_Thyroid Histology_** Functional Unit

Thyroid Follicle - a spherical space lined by epithelial cells that are low cuboidal when inactive but nearly columnar when active

**_Thyroid Function_** Main thyroid hormones

T3 and T4 are the main thyroid hormones

**_Thyroid C Cells_** Location

Found adjacent to follicular cells. Within basal lamina surrounding follicle, but not in contact with the colloid

**_Thyroid C Cells_** Secretory Product

Calcitonin. This inhibits osteoclast activity and lowers blood calcium.

**_Parathyroid Glands_** What are they?

Usually 4 small oval glands on posterior surface of thyroid gland. Produce parathyroid hormone which increases serum calcium.

**_Parathyroid Glands - Cell types_** Adipose Cells

...

**_Parathyroid Glands - Cell types_** Chief cells

Small, lightly stained cells with dark nuclei. Cells that secrete PTH.

**_Parathyroid Glands - Cell types_** Oxyphils

Larger than chief cells. Eosinophilic. Appear at puberty becoming more numerous with age. Large numbers of mitochrondria but function unknown.

**_Adrenal Glands_** Adrenal Cortex

Formed of epithelial cells

**_Adrenal Glands_** Adrenal Medulla

Formed of neural crest cells. Essentially a modified sympathetic ganglion where postganglionic neurons have lost axons and release trasmitter into the blood instead

**_Adrenal Glands_** Surrounded by

Thick capsule with connective tissue trabeculae extending inwards through the cortex

Adrenal Glands

**_Adrenal Cortex_** Three distinct layers or zones

From outer to inner - Zona Glomerulosa Zona Fasciculata Zona Reticularis

**_Steroid Hormones Secreted by Adrenal Cortex_** Mineralocorticoids

Involved in electrolyte and fluid homeostasis. Principally aldosterone. Produced in zona glomerulosa.

**_Steroid Hormones Secreted by Adrenal Cortex_** Glucocorticoids

Involved in many aspects of metabolism. Stored in Zona Fasciculata. Principal glucocorticoid is cortisol, whose secretion is controlled by ACTH from the anterior pituitary

**_Steroid Hormones Secreted by Adrenal Cortex_** Sex hormones

Androgens produced in small amounts by the Zona Reticularis

Adrenal Cortex Summary

**_Adrenal Medulla_** Function

Reinforces the action of the sympathetic nervous system at times of stress. Contain granules of adrenaline and noradrenaline which are released into the blood, preparing the body for "fight or flight" at times of stress.

**_Endocrine Pancreas_** Consists of

About one million small, scattered, islands of tissue called islets of Langerhans. Rich blood supply to these.

**_Cells of the Endocrine Pancreas_** Insulin Secreting Cells

About 70% of the cells. Also called B cells or ß Cells

**_Cells of the Endocrine Pancreas_** Glucagon Secreting Cells

About 20% of the cells. Also called A or alpha cells

**_Cells of the Endocrine Pancreas_** Somatostatin Secreting Cells

About 5-10% of cells. Also called D or delta cells

**_Testes_** Produce

Spermatozoa, but also secrete testosterone

**_Testes_** Leydig Cells

In the interstices between the seminiferous tubules are responsible for testosterone production in the testes

**_Ovaries_** Produce

Ova, but also secrete the female sex hormones oestrogen and progesterone

**_Theca Interna_** Location and function

Surrounding developing ovarian follicle. Are responsible for much of the production of female sex hormones