The Endocrine System

Endocrine cells/glands secrete hormones directly into the blood to be carried towards target tissues.

What is a neuroendocrine cell?

Fill in the blanks below to define the different types of chemical signalling. [blank_start]Autocrine[blank_end] - cells release hormones which act on themselves Signalling across [blank_start]gap junctions[blank_end] - cells release hormones which travel through the cytosol to a neighbouring cell [blank_start]Paracrine[blank_end] - cells release hormones which act on different neighbouring cells [blank_start]Endocrine[blank_end] - cells release hormones which target distant target cells via the bloodstream [blank_start]Neuroendocrine[blank_end] - cells are stimulated by synaptic signals causing the production of an action potential leading to the release of hormones into the bloodstream

Peptide hormones are synthesised first as large preprohormones. They are then cleaved by proteolytic enzymes which forms prohormones.

How are prohormones released from the cell?

Prohormones are protein bound in the bloodstream.

What gives a hormone a longer half life?

Check the types of hormones that are released by neurosecretory cells.

Check the types of hormones that are released by epithelial tissues.

Steroid hormones are stored in glands.

Check the true statements about steroid hormones.

Which amino acid are amine hormones commonly derived from?

Thyroid hormones and catecholamines can both cross the cell membrane.

Thyroid hormones are stored in the thyroid gland bound to what substance?

Catecholamine hormones are unbound in circulation meaning they have a short half life.

Thyroid hormones are protein bound in circulation.

Eicosanoids are local chemical messengers - they act with autocrine/[blank_start]paracrine[blank_end] activity. They are derived from [blank_start]arachidonic acid[blank_end] found in plasma membrane phospholipids. One example of an eicosanoid is the [blank_start]prostaglandins[blank_end] which promote inflammation, support ovulation and inhibit gastric secretions.

Which hormones have intracellular receptors in the cytoplasm or nucleus and act upon cells by altering gene transcription? Check all that apply.

What facilitates the binding of a steroid receptor to DNA?

Fill in the blanks below to give a brief overview of the mechanism of lipid-insoluble hormones. 1. The hormone binds to the [blank_start]extracellular[blank_end] domain of a receptor. 2. The receptor undergoes a [blank_start]conformational shape change.[blank_end] 3. This triggers a signalling cascade via a [blank_start]second messenger[blank_end] mechanism to give the final response.

Fill in the blanks below to describe the development of the pituitary gland. 1. The embryonic [blank_start]hypothalamus[blank_end] and roof of [blank_start]mouth[blank_end] develop outgrowths towards one another. 2. These evaginations fuse to form one structure, however they maintain their differing composition and function due to their differing [blank_start]embryological[blank_end] origins. 3. The [blank_start]sella turcica[blank_end] develops inferior to the gland.

The posterior pituitary lobe develops from neuroectoderm of the hypothalamus and the anterior pituitary lobe develops from the roof of the mouth.

Label this image to show the anatomy of the pituitary gland.

In which lobe of the pituitary gland are the hormones synthesised in the cell bodies of the nuclei, transported down axons, stored in nerve terminals and released into the blood upon stimulation?

What hormones does the posterior pituitary gland secrete?

What is the action of anti-diuretic hormone (ADH)?

Which hormone increases uterine contractions during birth and milk ejection during suckling in a positive feedback mechanism?

In which lobe of the pituitary gland will the hormones be released from hypothalamic nuclei into portal blood vessels at the median eminence to be transported down into the pars distalis and out of the lobe in the blood?

Which blood vessel supplies the median eminence and stalk of the pituitary gland?

What does the inferior hypophyseal artery supply? Check all that apply

Fill in the blanks below to describe the endocrine cell types of the anterior pituitary gland. G[blank_start]onadotroph[blank_end] cells secrete l[blank_start]uteinising[blank_end] hormone and f[blank_start]ollicle stimulating[blank_end] hormone. C[blank_start]orticotroph[blank_end] cells secrete a[blank_start]drenocorticotrophic[blank_end] hormone and [blank_start]melanocyte[blank_end] stimulating hormone. S[blank_start]omatotroph[blank_end] cells secrete somatotrophin, also known as g[blank_start]rowth[blank_end] hormone. T[blank_start]hyrotroph[blank_end] cells secrete [blank_start]thyroid[blank_end] stimulating hormone. All of the hormones mentioned above are trophic to other specific endocrine glands. L[blank_start]actotroph[blank_end] cells secrete [blank_start]prolactin[blank_end], which does not affect any downstream hormones.

The only way of controlling the release of hormones from the anterior pituitary is by negative feedback.

Fill in the blanks below to describe the secretion of hypothalamic hypophysiotrophic hormones on the anterior pituitary gland. The hypothalamic hypophysiotrophic hormones are released into the [blank_start]pituitary portal[blank_end] system from nerve terminals in the [blank_start]median eminence[blank_end] of the hypothalamus. They then travel through the portal system and out of the lobe.

Fill in the blanks below to describe a negative feedback mechanism affecting the anterior pituitary gland. 1. Low temperature stimulates the [blank_start]hypothalamus[blank_end] in the brain 2. Hypothalamic cell bodies release [blank_start]thyrotropin releasing[blank_end] hormone (TSR) into the [blank_start]pituitary portal system[blank_end] 3. TSR activates the [blank_start]thyrotroph[blank_end] cells in the anterior pituitary to secrete [blank_start]thyroid stimulating[blank_end] hormone (TSH) 4. TSH stimulates the [blank_start]thyroid[blank_end] glane to secrete T3 and T4 which [blank_start]increase[blank_end] body temperature 5. High concentrations of these enzymes triggers the hypothalamus to slow the mechanism

The hypothalamic hypophysiotrophic hormones stimulate the release of specific hormones from the anterior pituitary.