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Physiological Systems > Endocrine System > Flashcards

Endocrine System Flashcards

1
Q

What is neuroendocrine system

A

The nervous system and the endocrine system work together to coordinate body functions and control homeostasis:

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2
Q

How does the nervous system act on the endocrine system

A

-Nervous system releases neurotransmitters that act on neurons, muscle fibres and glands (endocrine / exocrine) ~ nerve AP’s produce their effects within milliseconds

-Endocrine system releases hormones into extracellular fluids / blood stream which delivers them to most body cells
~ hormones produce their effects within a few seconds to several hours

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3
Q

Name organic chemical messengers/signalling molecules

A

-amines
-eicosanoids such as prostaglandins
-steroids
-proteins,peptides,glycoproteins

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4
Q

What are eicosanoids

A

Lipid based signalling molecules that pay a unique role in initiating an immune response

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5
Q

Hormones

A

-organic chemical messengers/signalling molecules
-secreted by specialised glands,scattered cells and nerves
-transported in the blood stream or by simple diffusion
-categorised according to their target sites
-regulate existing reactions within cells

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6
Q

List categories of hormones according to their target sites

A

-endocrine
-neurohormone
-paracrine(hormone produced at one site but active at a different site in the body)
-neurotransmitter
-autocrine(has effect on one cell and it’s the one that’s its secreted from)
-pheromone

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7
Q

Main hormone producing tissues

A

Hypothalamus
>releasing hormones:GHRH,CRH,TRH,GnRH,vasopressin
>inhibitory hormones: dopamine,somatostatin

Pituitary gland
>anterior : growth hormone ,prolactin, ACTH,MSH,TSH,FSH,LH
>posterior :oxytocin,vasopressin(antidiuretic hormone)

Thyroid gland
>thyroid hormones(T3 and T4)

Parathyroid gland
>parathyroid hormones

Adrenal glands
>adrenal cortex:cortisol,aldosterone,adrenal androgens
>adrenal medulla: adrenaline,noradrenaline

Pancreas:insulin,glucagon

Testes:testosterone

Ovaries;oestrogen progesterone e

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8
Q

The pituitary gland has two parts, what are they?

A

Anterior and posterior

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9
Q

Distribution of hormones to target cells

A

• Hormones can reach tissues / cells by diffusion or via blood
• Hormone actions can be either:
➢ autocrine (on-self)
➢ paracrine (local)
➢ endocrine (distant)
• Hormones exert targeted responses because cells have specific receptors

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10
Q

Water soluble hormones

A

-hydrophilic
-cell surface receptors
-eg polypeptides,oxytocin,ADH

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11
Q

Lipid soluble hormones

A

-hydrophobic
-intracellular receptors
-eg steroids ,T3 thyroid hormone

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12
Q

Hormone receptors

A

• The ability of cells to respond to hormones depends on the expression of specific receptors by the target cells
~ many hormones have different receptor sub-types which can be linked to different sub-types of G proteins eg:
~ adrenergic alpha-1(Gq), alpha-2(Gi), beta-1(Gs), beta-2(Gs)
• Receptors are located on the plasma membrane or inside target cells; there are three main types:
-cell surface :peptides ,adrergenic,histamine
-cytosolic/nuclear: steroid hormones
-Nuclear:thyroid(triiodothyronine/t3)
• Hormones must bind to their receptor(s) to form hormone- receptor complexes that produce their effects / actions

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13
Q

Steroid receptors

A

• Steroid hormones diffuse into cells, bind to cytosolic ‘signal’ receptors & form receptor complexes
➢cortisol, aldosterone, oestrogen, progesterone testosterone & vitamin D
• receptor complexes bind to DNA acceptor sites
• DNA binding starts mRNA and proteins synthesis
• Receptors are recycled but the hormone is inactivated
• Thyroid hormone (T3) has a similar mechanisms

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14
Q

Hormones can bind to a cell
membrane receptor and cause….?

A
  1. Cause the opening/closing of an ion channel
  2. Signal an intracellular “second messenger” cascade
  3. Cause an enzyme to be activated which converts a protein into an active form
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15
Q

A steroid hormone binds inside
the cell to which organelle to exert its effects?

A

Nucleus

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16
Q

Name the 3 mechanisms of control provided by the hypothalamus and the pituitary gland

A

1) Hypothalamus and Anterior Pituitary:

2) Hypothalamus and Posterior Pituitary:

3) Adrenal Gland:

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17
Q

The hypothalamus signals to…?

A

-anterior pituitary
-posterior pituitary
-adrenal gland

18
Q

1) Hypothalamus and Anterior Pituitary mechanism

A

~ secretion of regulatory hormones (releasing & inhibitory)
~ these hormones control the secretary activity of the anterior lobe of the pituitary gland

19
Q

Hypothalamus and Posterior Pituitary mechanism

A

~ ADH and Oxytocin are formed in the hypothalamus
~ both are released from the posterior pituitary

20
Q

Adrenal Gland mechanism

A

~ sympathetic output to the adrenal medulla (adrenalin)
~ ACTH control of cortisol release from the adrenal cortex

21
Q

Hypothalamus hormones

A

Hypothalamic hormone secreting neurons secrete releasing hormones (RH) or inhibitory hormones (IH) into blood vessels to regulate anterior pituitary hormone secretion

22
Q

Hormones released by the Hypothalamus

A

GHRH & GHIH PRH & PIH GnRH
TRH CRH
MSHRH & MSHIH

23
Q

Hormones released by the anterior pituitary glad

A

growth hormone (GH)
prolactin (PRL)
follicle stimulating (FSH)
& luteinizing hormone (LH)
thyroid stimulating hormone (TSH) adrenocorticotrophic hormone (ACTH)
melanocyte stimulating hormone (MSH)

24
Q

Hypothalamus and pituitary hormone secretion

A

•Hypothalamus and Pituitary Hormone Secretion
The hypothalamus controls pituitary hormone secretion

these neurons control hormone secretion by the anterior pituitary

25
Q

Anti-Diuretic Hormone is
released from….

A

Posterior Pituitary

26
Q

What’s a hypophyseal portal vessels in

A

System of blood vessels that connects the hypothalamus and the anterior pituitary gland

27
Q

Stimuli for the secretion of hormones

A

-action potentials → hypothalamic neurohormones -hypothalamic neurohormones → anterior pituitary hormones
-TSH from the anterior pituitary → thyroid hormone -acetylcholine neurotransmitter → adrenal medulla hormones
-glucose → insulin, glucagon
-low / high blood Ca++ → parathyroid / calcitonin hormones
-other (eg tissue injury) → histamine, cytokines

28
Q

Where are many hormones stored

A

Many hormones are stored in vesicles which must fuse with the plasma membrane to be secreted:
➢increased intracellular Ca2+ is required for the vesicles to fuse with the plasma membrane

29
Q

Thyroid gland

A

Thyroid gland, in the neck, is 10-20 g and contains spherical follicles filled with colloid
➢ colloid contains thyroglobulin containing T3 & T4 hormone

30
Q

Regulation of thyroid hormone release

A

-Hypothalamus releases TRH (Thyroid Releasing Hormone)
-Increased cellular metabolism
-T3 & T4 enter blood and circulate to target cells
-Thyroid gland releases thyroid hormones
-Thyroid Stimulating Hormone

31
Q

Thyroid actions in cells

A
  1. T3 enters nucleus
  2. T3 binding releases the co- repressor (CoR) from the thyroid hormone receptor (TR)
  3. Co-activator (CoA) assists T3 gene activation
  4. Gene expression is regulated by T3
32
Q

Thyroid Hormones cause a
……….. in cell respiration, O2
Consumption, cardiac output,
ventilation, thermogenesis and
food intake

A

Increase

33
Q

Effect of t3 and t4

A

-increased metabolic rate

– Thermogenesis
– Increased basal metabolic rate
– Increased O2 consumption
– Increased Cardiac Output and Ventilation

34
Q

Stress response

A

-Stress responses are adaptive responses that:
~ enable individuals to cope more effectively with stress
~ maintain / re-establish homeostasis through physiological or behavioral changes
- fight or flight response: animals react to threats via activation of the sympathetic nervous system (involves adrenalin & noradrenalin)

35
Q

Who used the term fight or flight response in 1915

A

Walter cannon

36
Q

Who described the general adaptation syndrome

A

-1946 hans Selye
-described it with 3 stages:alarm,resistance,exhaustion
-also observed that stress also increases infection/illness

37
Q

Stress and the Hypothalamus-Pituitary-Adrenal Axis

A

• Stress involves increased levels of arousal / activation:
~ generalised activation of the nervous system and secretion of stress hormones (adrenalin & cortisol)
• Acute ‘fight or flight’ stress response involves:
~ increased sympathetic activity (adrenergic)
~ adrenal gland secretion of adrenaline & noradrenaline
~ decreased parasympathetic activity (cholinergic)
• Hypothalamus-pituitary-adrenal (HPA) axis releases:
~ corticotrophin-releasing factor (CRF) by the hypothalamus
~ adrenocorticotrophic hormone release by the pituitary gland
~ cortisol release by the cortex of the adrenal gland

38
Q

Short term biological stress response

A

• Combined effects of noradrenaline (nor-epinephrine) and adrenaline (epinephrine) act within seconds or minutes:
~ increased blood pressure
~ increased breathing rate
~ increased metabolic rate
~ glycogen broken down to
glucose causing increased blood glucose

Adrenal Secretion includes:
80% adrenaline (HR & Systolic BP) (diastolic BP)
20% noradrenaline (S & D BP) <1% dopamine (↑ HR & BP)

• Change in blood flow (vasodilatation / constriction) leading to:
~ increased alertness and muscle function
~ decreased digestive, excretory, reproductive function

39
Q

What’s the HPA axis

A

-hypothalamic pituitary adrenal axis is the main stress response system
-provides links between the brain and body via hormones

40
Q

Hormones from the anterior pituary

A

Prolactin
ACTH
GH
LH
FSH

41
Q

Physiological effects of adrenaline

A

Increased heart rate

Increased diastolic blood pressure

Physiological Systems (25 decks)

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