Endocrine System Flashcards by Hanna Chodorowska

What is neuroendocrine system

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

How well did you know this?

Not at all

Perfectly

How does the nervous system act on the endocrine system

-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

How well did you know this?

Not at all

Perfectly

Name organic chemical messengers/signalling molecules

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

How well did you know this?

Not at all

Perfectly

What are eicosanoids

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

How well did you know this?

Not at all

Perfectly

Hormones

-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

How well did you know this?

Not at all

Perfectly

List categories of hormones according to their target sites

-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

How well did you know this?

Not at all

Perfectly

Main hormone producing tissues

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

How well did you know this?

Not at all

Perfectly

The pituitary gland has two parts, what are they?

Anterior and posterior

How well did you know this?

Not at all

Perfectly

Distribution of hormones to target cells

• 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

How well did you know this?

Not at all

Perfectly

Water soluble hormones

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

How well did you know this?

Not at all

Perfectly

Lipid soluble hormones

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

How well did you know this?

Not at all

Perfectly

Hormone receptors

• 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

How well did you know this?

Not at all

Perfectly

Steroid receptors

• 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

How well did you know this?

Not at all

Perfectly

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

Cause the opening/closing of an ion channel
Signal an intracellular “second messenger” cascade
Cause an enzyme to be activated which converts a protein into an active form

How well did you know this?

Not at all

Perfectly

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

Nucleus

How well did you know this?

Not at all

Perfectly

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

1) Hypothalamus and Anterior Pituitary:

2) Hypothalamus and Posterior Pituitary:

3) Adrenal Gland:

How well did you know this?

Not at all

Perfectly

The hypothalamus signals to…?

Study These Flashcards

-anterior pituitary
-posterior pituitary
-adrenal gland

1) Hypothalamus and Anterior Pituitary mechanism

Study These Flashcards

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

Hypothalamus and Posterior Pituitary mechanism

Study These Flashcards

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

Adrenal Gland mechanism

Study These Flashcards

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

Hypothalamus hormones

Study These Flashcards

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

Hormones released by the Hypothalamus

Study These Flashcards

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

Hormones released by the anterior pituitary glad

Study These Flashcards

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

Hypothalamus and pituitary hormone secretion

Study These Flashcards

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

these neurons control hormone secretion by the anterior pituitary

Anti-Diuretic Hormone is released from....

Posterior Pituitary

What’s a hypophyseal portal vessels in

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

Stimuli for the secretion of hormones

-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

Where are many hormones stored

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

Thyroid gland

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

Regulation of thyroid hormone release

-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

Thyroid actions in cells

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

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

Increase

Effect of t3 and t4

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

Stress response

-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)

Who used the term fight or flight response in 1915

Walter cannon

Who described the general adaptation syndrome

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

Stress and the Hypothalamus-Pituitary-Adrenal Axis

• 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

Short term biological stress response

• 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

What’s the HPA axis

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

Hormones from the anterior pituary

Prolactin ACTH GH LH FSH

Physiological effects of adrenaline

Increased heart rate Increased diastolic blood pressure

Endocrine System Flashcards

(41 cards)