Introduction to Endocrinology Flashcards

1
Q

What is the endocrine system?

A

The endocrine system is essentially the ‘hormone system’ and is just communication between cells. It influences metabolic activity by means of hormones.

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2
Q

How is the endocrine system different to the nervous system?

A

Endocrine system initiates responses slowly (NS is rapid); ES is via hormones released into the blood (NS is via action potentials and neurotransmitters); ES can target anywhere blood reaches (NS is at specific locations determined by axon pathways); ES has hormones that act over long distances (Neurotransmitters act over very short distances)

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3
Q

What is the hypothalamus?

A

Hypothalamus is a part of the brain that controls the release of hormones from the pituitary gland in 2 ways

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4
Q

What are the 2 ways that the hypothalamus controls the release of hormones from the pituitary gland?

A

Posterior pituitary: action potentials travel down the axons of hypothalamic neurones, causing release from their axon terminals in the posterior pituitary
Anterior pituitary: Communicates via hormones released into a system of blood vessels

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5
Q

What is an endocrine gland?

A

Glands which secrete hormones directly into the bloodstream through which they travel to affect distal organs

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6
Q

What is a hormone?

A

Regulatory substance produced by the endocrine gland and transported in tissue fluid to stimulate specific target tissues into action

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7
Q

What is a paracrine?

A

A hormone which has effect only in the vicinity of the gland secreting it (cells near where it is released- same tissue)

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8
Q

What is an autocrine?

A

A cell produced substance that has an effect only on the cell in which it is secreted

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9
Q

What are the different ways that hormones are categorised?

A

Amino acid based (can be amines- amino acid with modified R group, peptides- short amino acid sequence or proteins- long amino acid sequence). Amino acid based hormones are usually water soluble and cannot cross the plasma membrane so receptors are on the cell surface membrane.
Steroid hormones- Made from cholesterol. Lipid based so can cross the plasma membrane so receptors are within the cell.
Eicosanoid- Made from Omega 3 or 6 and essential fatty acids.

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10
Q

What is a Juxtacrine?

A

Direct cellular communication often through binding cell surface receptors

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11
Q

What is oxytocin and ADH?

A

Oxytocin- strong stimulant of uterine contraction (tightening and shortening of uterine muscles
ADH- Secreted into blood to prevent dehydration as more water is reabsorbed from the urine so therefore less urine is produced.

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12
Q

What happens when GHRH and GHIH are released by the hypothalamus?

A

GHRH- Growth hormone releasing hormone- stimulates GH release
GHIH- Growth hormone inhibiting hormone (also called somatostatin)- inhibits GH release

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13
Q

What are trophic hormones?

A

Hormones secreted by the anterior pituitary gland

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14
Q

What is humoral Stimuli?

A

When hormones are released when the level of a molecule changes to outside homeostatic ‘normal’. (e.g. pancreas releases insulin when glucose level increases in the blood)

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15
Q

What is neural stimuli?

A

Hormone release when nerves in the endocrine gland provide the signal

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16
Q

What is hormonal Stimuli?

A

Hormone release when another hormone stimulates the gland.

16
Q

If the posterior pituitary is removed, why are the effects of the hormonal symptoms go away?

A

Hormones can still be released from the neurones (they are made in the hypothalamus not the posterior pituitary) and a new capillary bed will be made (to distribute the hormones)