Endocrine system Flashcards

1
Q

Circadian rhythm

A

Sleep / wake cycle. Biological processes that follow a 24-hour cycle

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2
Q

Colostrum

A

Firstly produced breast fluid containing water, lacto-sugar & antibodies. Acts as a laxative to encourage BM which removes bilirubin build up

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3
Q

Corpus luteum

A

A hormone secreting structure that develops in an ovary following ovulation

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4
Q

Glands

A

There are two type of glands: Exocrine and Endocrine.

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5
Q

Glands; Endocrine

A

Ductless, secreting hormones directly into the blood. Inc. Hypothalamus (neuroendocrine gland), pituitary (glandular and neuroendocrine), pineal, thyroid, parathyroid, adrenal, pancreatic: islets of Langerhans, Thymus, Ovaries, Testes

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6
Q

Glands; Exocrine

A

Excrete products into ducts leading to body cavities / organ / skin e.g. salivary glands (saliva), gastric glands (digestive enzymes), mammary glands (milk)

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7
Q

Homeostasis system controls (x 2)

A

Two control systems control homeostasis;
Endocrine and Autonomic Nervous System:

Endocrine system;
Slower change, More precise
Longer duration, Hormones,
Control centre = hypothalamus

Autonomic nervous system;
Rapid change, less precise
Shorter duration, neurotransmitters,
Control centre - central nervous system

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8
Q

Hormones

A

Chemical messengers released into blood from glands which produce them. The endocrine system coordinates the activity of organs through hormones. Have specific target cells, can be Peptides, Steroids, Amino acid derivatives

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9
Q

Hormone derivatives; peptides

A

Proteins (water soluble) i.e. insulin

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10
Q

Hormone derivatives; steroids

A

Sex hormones; e.g. oestrogen

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11
Q

Hormone derivatives; Amino acid

A

Adrenaline, thyroxine

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12
Q

Hormones: Releasing hormones

A

Releasing hormones (5). Hypothalamus signals the anterior pituitary to stimulate particular glands & cause them to release secretions. Inc:
* Thyrotropin releasing hormone (TRL),
* Growth hormone releasing hormone (GHRH),
* Corticotropin releasing hormone (CRH),
* Prolactin releasing hormone (PRH),
* Gonadotropin releasing hormone (GnRH)

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13
Q

Hormones: Inhibiting hormones

A

Inhibiting hormones (2);. Sent from the hypothalamus to the anterior pituitary. Stop the signals to the pituitary. Inc:
* Growth hormone inhibiting hormone (GHIH)
* Prolactin inhibiting hormone - Dopamine (PIH)

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14
Q

Hormone (Releasing); Gonadotropin releasing hormone (GnRH)

A

Releasing hormone. Released by the hypothalamus to signal the pituitary to secrete follicle stimulating hormone (FSH) and luteinising hormone (LH)
Target tissue - ovaries & testes

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15
Q

Hormone (Releasing); Growth hormone releasing hormone (GHRH)

A

Releasing hormone; Released by the hypothalamus to signal the pituitary to secrete growth hormone (GH)
Target tissue = most body tissues

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16
Q

Hormones (Releasing); Corticotropin releasing hormone (CRH)

A

Releasing hormone. Released by the hypothalamus to signal the anterior pituitary to secrete: adrenocorticotropic hormone (ACTH) and melanocyte stimulating hormone (MSH)
Target tissue (ACTH) – adrenal cortex
Target tissue (MSH) – skin

17
Q

Hormones (Releasing); Prolactin releasing hormone (PRH)

A

Releasing hormone. Released by the hypothalamus to signal the anterior pituitary to secrete prolactin
Target tissue – breasts

18
Q

Hormones (Releasing); Thyroid releasing hormone (TRH)

A

Releasing hormone. Released by the hypothalamus to signal the anterior pituitary to secrete Thyroid stimulating hormone (TSH)
Target tissue = thyroid gland

19
Q

Hormones (Inhibiting) growth hormone inhibiting hormone (GHIH)

A

Inhibiting hormone. Released by the hypothalamus to signal the pituitary to stop secreting growth hormone (GH)
Target tissue = most body tissues

20
Q

Hormones (Inhibiting) Prolactin inhibiting hormone (dopamine) (PIH)

A

Inhibiting hormone. Released by the hypothalamus to signal the pituitary to inhibit prolactin hormone (dopamine)
Target tissue - breasts

21
Q

Hormone; Adreno-corticotropic hormone (ACTH);
(Anterior pituitary):

A

Activity: Output of steroid hormones (esp. cortisol) and & circadian rhythm (sleep / wake cycle)

Glucocorticoids (cortisol) 95%;
- glucogenisis (production of glucose)
- break down proteins & fats (energy fuel)
- Anti inflammatory & reduces immune response

Mineralocorticoids;
- Aldosterone (RAAS)
- helps to increase BP by reabsorption of Na+ in kidneys & excretion of K
- removes acid from the body

Sex hormones - Androgens (DHEA);
- Increase muscle mass
- helps T4 - T3 conversion
Converts testosterone, then Oestrogen

Increased production: Hypoglycaemia, exercise, stressors (emotions, fever), Interleukin 1 (inflammatory response to infection)
Production; Highest in morning and lowest at midnight
Stimulated by; Corticotropin releasing hormone (CRH) - anterior pituitary
Target tissue = Adrenal cortex

22
Q

Hormones; Melanocyte stimulating hormone (MSH)
(Anterior pituitary)

A

Activity; Role in skin, hair and eye pigmentation in humans
Production; Produced by the pituitary in response to UV light, can be excessively produced as part of some pathologies e.g. hyperpigmentation of skin in Addison’s disease
Stimulated by; Corticotropin releasing hormone (CRH) - anterior pituitary
Target tissues; Skin
Melanin= skin pigment, cyte = cell

23
Q

Hormones; Thyroid stimulating hormone (TSH);
(Anterior pituitary)

A

Activity: Growth & activity of the thyroid gland /increasing thyroid hormone production – Thyroxine (T4) & Triiodothyronine (T3)
T4/T3 - Increases metabolism in our cells, heat production, essential for growth and development of CNS

T4/T3 in blood are called thyroxine.
There is more T4 but T3 is 3-4x more potent (bio active)
Selenium is required for conversion of T4 to T3
Carried in blood on a protein called thyroxin binding globulin (TBG)

Production; lowest levels – early evening, highest levels – during night
Stimulated by; Thyroid releasing hormone (TRH) – anterior pituitary
Target tissues: Thyroid gland

24
Q

Hormone; Growth hormone (GH);
(Anterior pituitary):

A

Activity; 1) Regulates metabolism in many organs, 2) Simulates release of insulin-like growth factors (IGF’s) in cells, 3) Promotes growth & division of most body cells (esp. bone & muscle), 4) Breaks down fats and glycogen
Increased production; Night time (sleep), hypoglycaemia, exercise, childhood and adolescence
Stimulated by; Growth hormone releasing/inhibiting hormone (GHRH & GHIH) - anterior pituitary
Target tissues; most body tissues

25
Q

Hormone; Luteinising hormone (LH);
(Anterior pituitary)

A

Activity; Triggers ovulation & formation of the ‘corpus luteum’ in females, increases secretions of progesterone (F), stimulates secretions of testosterone (M)
Stimulated by; Gonadotropin releasing hormone (GnRH)
Target tissue: Ovaries / testes

26
Q

Hormone; Follicle stimulating hormone (FSH);
(Anterior pituitary):

A

Activity; Production of gametes (sex cells) in males & females, increases oestrogen production (F), stimulates testosterone production (M)
Stimulated by; gonadotropin releasing hormone (GnRH) - anterior pituitary
Target tissue: Ovaries / testes

27
Q

Hormones; Prolactin (PRL);
(Anterior pituitary)

A

Activity;
1) Stimulates lactation (prolactin + oxytocin = lactation),
2) Prevents pregnancy during lactation (inhibits GnRH),
3) Breast maturation after childbirth (matures mammary glands in pregnancy)
Production; After birth (delivery of placenta), Suckling (the more milk removed, the more produced), Emotional stress, sleep
Stimulated by; Prolactin releasing hormone (PRH) – Anterior pituitary
Target tissues: Breasts

28
Q

Hormones; Oxytocin
(Posterior pituitary)

A

Activity; 1) Contracts uterus in childbirth (parturition), 2) Contracts lactating breast, 3) Bonding hormone (mother with baby, social bonding – trust, skin contact, ‘cuddle hormone’)
Production; Suckling, Childbirth (positive feedback), Emotional state – fear / anxiety may inhibit release of oxytocin or milk let down. Emotions can trigger oxytocin – hearing a baby cry
Stimulated by: Posterior pituitary - Hypothalamus
Target tissues; Uterine smooth muscle, mammary gland
Oxy = sharp, tocos = labour.

29
Q

Hormone; Antidiuretic hormone (AFD)
(Posterior pituitary);

A

Activity; 1) reduces urine output - stimulates reabsorption water in kidneys
2) Vasoconstriction in skin & abdominal organs to increase BP
Production; increases osmotic pressure, hypovolaemia (reduced fluid intake), thirst, vomiting)
Inhibition: reduced osmotic pressure, increased fluid intake, alcohol
Stimulated by; posterior pituitary - hypothalamus monitors body fluid
Target organ; Kidneys, Sudoriferous (sweat) glands, arterioles
Anti = against, diuresis = urination.

30
Q

Hypothalamus

A

Hormones are synthesises here. Sends signals to the pituitary to help control endocrine system. Pituitary & hypothalamus = major link between nervous and endocrine system – control growth, development, metabolism & homeostasis

31
Q

Lactation

A

Milk production triggered by release of prolactin. It takes 2-3 weeks for milk production to begin. 1st breast fluid is colostrum

32
Q

Pituitary gland

A

AKA master endocrine gland – controls many other endocrine glands in body. Self-regulated (signalled) by hypothalamus, which is connected by a stalk of nerve fibres & capillary network. Has anterior and posterior region.

33
Q

Pituitary gland; Anterior

A

Receives 7 stimulating / releasing hormones from hypothalamus – to synthesises & releases: Growth hormone (GH)
* Thyroid stimulating hormone (TSH),
* Follicle stimulating hormone (FSH),
* Luteinising hormone (LH),
* Prolactin (PRL),
* Adrenocorticotropic hormone (ACTH)
* Melanocyte stimulating hormone (MSH)

34
Q

Pituitary gland; Posterior

A

Receives nerve impulses from hypothalamus & releases hormones;
* Oxytocin
* Antidiuretic hormone (ADH)

35
Q

Regulation of hormones

A

Hormones are secreted by; nervous system signals, chemical changes in the blood, other hormones. Controlled through positive & negative feedback loops

36
Q

Regulation of hormones; Receptors

A

Hormones have specific target cells; they influence the activity of the target cells by binding to the receptors. They are made up of proteins. They allow hormones to have a stimulating or inhibitory effect – down or up regulation

37
Q

Regulation of hormones; Down regulation

A

If a hormone is present in excess, the number of target cell receptors may decrease (e.g. hormones during puberty)

38
Q

Regulation of hormones; Up-regulation

A

A deficiency in hormone causes an increase in the number of receptors on target cells e.g. increased no. of oxytocin receptors in 3rd trimester pregnancy

39
Q

Tissues; Endocrine

A

Some tissues are not considered glands but have endocrine function (produce hormones) = Adipose, Heart, GIT, Liver, Placenta, Kidneys, Skin

Adipose - lepton (suppresses food intake) and resisting (blood glucose)

Heart - atrial natriuretic peptide (blood pressure)

GIT / Stomach - ghrelin and gastrin (satiety & gastric emptying, stomach acid production)

Liver - angiotensinogen (precursor for BP regulation), insulin-like growth factor (IGF), Thrombopoietin (platelet production)

Placenta - human chorionic gonadotropin (hCG), progesterone

Kidneys - erythropoietin (RBC production) & Calcitriol (Vit D)

Skin - cholecalciferol (Vit D)