The Endocrine System Flashcards Preview

ESA 1 - Body Logistics > The Endocrine System > Flashcards

Flashcards in The Endocrine System Deck (26):
1

What is neurocrine communication?

Neurons that secrete hormones into the bloodstream.

2

What are the 3 examples of neurocrine communication in the body?

- Anterior pituitary
- Posterior pituitary
- Adrenal medulla

3

What are the major endocrine glands?

Pineal gland
Hypothalamus
Pituitary gland

Thyroid gland
Parathyroid gland

Adrenal glands
Pancreas
Kidney
Gonads

4

Suggest examples of organs containing endocrine cells.

Thymus
Heart
Liver
Stomach
Kidney
Small intestine

5

Where is the thymus found and what is its role?

- Located in the superior mediastinum.
- Is fully formed and functional at birth, involuted after puberty and is mostly fat by late teens.
- Role in the maturation of bone marrow-derived stem cells into immunocompetent T cells = thymic cell education. Produces thymosin, a hormone that promotes T cell maturation.

6

What do hormones control and regulate?

1. Reproduction
2. Metabolism & energy balance
3. Growth & development
4. Body defences
5. General homeostasis (inc. water, nutrient & electrolyte balance of the blood)

7

What are the major types of hormones?

- Amino acid (tyrosine)-derived hormones
- catecholamines
- thyroid hormones

- Peptide hormones

- Steroid hormones

8

Describe the properties (transport, R location, MOA) of peptide hormones.

- Hydrophilic:
Transport in blood - dissolved in plasma
Receptor location - cell membrane

- Action on R binding:
Trigger synthesis of cytosolic second messengers
Trigger protein kinase activity

- Act in mins - hrs.
Plasma 1/2 life: mins

9

Describe the properties (transport, R location, MOA) of steroid hormones.

- Hydrophobic (lipophilic):
Transport in blood - bound to carrier proteins
Receptor location - cytoplasm or nucleus

- Action on R binding:
R-hormone complex controls transcription and stability of mRNA

- Act in hrs - days
Plasma 1/2 life: hrs

10

Describe the properties (transport, R location, MOA) of catecholamine hormones.

- Hydrophilic:
Transport in blood - dissolved in plasma
Receptor location - cell membrane

- Action on R binding:
Change in membrane potential
Trigger synthesis in membrane potential

- Act in msecs - secs
Plasma 1/2 life: seconds

11

Describe the properties (transport, R location, MOA) of thyroid hormones.

- Hydrophobic (lipophilic):
Transport in blood - bound to carrier proteins
Receptor location - nucleus

- Action on R binding
Activation of genes for transcription/translation

12

Give examples of peptide hormones.

Insulin
Glucagon
Prolactin
ACTH
PTH

13

Give examples of steroid hormones.

Oestrogen
Androgens
Aldosterone
Progesterone
Cortisol

14

Give examples of catecholamines.

Adrenaline
Noradrenaline

15

Give examples of thyroid hormones.

Thyroxine
Triiodothyronine

16

What are the different types of proteins made of?

- Peptide hormones: amino acids
- Catecholamines: amino acid (tyrosine) derivative
- Thyroid hormones: amino acid (tyrosine) derivative
- Steroids: derived from cholesterol lipids

17

What is the role of the pineal gland? How is its function inhibited?

- Produces melatonin: involved in the control of circadian rhythm. Inhibits the release of gonadotropin (LH and FSH).

- Light exposure inhibits melatonin release. Neuronal pathway is from retina to hypothalamus to pineal gland.

18

Why is the pineal gland visible on X-rays?

Calcifies in early adulthood.

19

How are the hypothalamus and pituitary gland connected?

Via the neurohypophyseal stalk

20

What is the role of the hypothalamus?

Regulates homeostasis:
Thermoregulation (panting, sweating, shivering)
Plasma osmolarity via osmoreceptors
Heart rate & BP
Feeding, satiety & GIT regulation
Circadian rhythms, wakefulness, sleep (afferents from retina)
Autonomic input/stimulation via connections to the sympathetic & parasympathetic systems
Emotion, sexual behaviour
Lactation (suckling/baby crying)

21

Which hormones does the hypothalamus produce?

- ADH & oxytocin: travel to posterior pituitary
- 6 hormones (4 stimulatory, 2 inhibitory): travel to anterior pituitary via the hypothalamo-hypophyseal portal system

22

What is special about the connection between the hypothalamus and anterior pituitary?

- Hypothalamo-hypophyseal portal system: 2 capillary beds in series.
- Neurocrine neurones in the hypothalamus secrete hormones that travel to anterior pituitary via capillaries portal system.

23

What is the system controlling the thyroid gland called?

Hypothalamic - pituitary - thyroid axis

24

Describe the hypothalamic - pituitary - thyroid axis.

1. Hypothalamus neurocrine cells secrete TRH (thyrotropin releasing hormone) into the portal blood supply.
2. TRH travels to anterior pituitary and stimulates TSH (thyroxin stimulating hormone) secretion.
3. TSH travels to thyroid and stimulates T3 and T4 release.
4. T3 and T4 travel to systemic receptors (control of metabolic rate) but also inhibit the production of TSH (short loop inhibition) and TRH (long loop inhibition) - NEGATIVE FEEDBACK.

25

What is the system controlling the adrenal glands (stress response) called?

Hypothalamic-pituitary-adrenal axis

26

Describe the hypothalamo-pituitary-adrenal axis.

1. Hypothalamus neurocrine cells release CRH (corticotropin releasing hormone) into the portal blood system.
2. CRH travels to the anterior pituitary and stimulates release of ACTH (adrenocorticotropic hormone).
3. ACTH travels to adrenal medulla and stimulates release of cortisol.
4. Cortisol inhibits the release of ACTH from the anterior pituitary (short loop inhibition) and CRH from the hypothalamus (long loop inhibition) - NEGATIVE FEEDBACK.