endocrine system U8

What other system is the endocrine very close in contact with and for what reason

Works with nervous system. Important for homeostasis

What is endocrine communication and what type of messengers does it involve

Considered indirect communication as cells do not need to by in close proximity (distant signalling) and involves chemical messengers called hormones

Are endocrine or nervous effects longer lasting and why

Endocrine communication has LONGER LASTING effects then nervous conductions as hormones enter directly through blood stream and hormones last longer in synapse then neurotransmitters

How are hormones carried to effect target organs

Carried in bloodstream so they can reach multiple targets

Endocrine vs exocrine

Endocrine-involves hormones to blood

Exocrine-creates secretions to body surface

What is paracrine vs autocrine communication

Paracrine-near signalling where stimulation is limited to neighbouring cells in the same tissue

Autocrine-self signalling. Where stimulation only effects the single cell that secretes the hormone

Endocrine-distant signalling through bloodstream

What are hormones

Chemical messengers

What can the binding of a hormone cause

Altered rate of genetic activity

altered rate of protein synthesis (rapid)

change in membrane permeability

3 classifications of hormones

Amino acid derivatives

Peptide hormones

Lipid derivatives

What are amino acid derivative hormones and the ones to know

Small molecules from tyrozenes. → catecholamines (norepinephrine, epinephrine, dopamine), thyroid hormones

What are peptide hormones and ones to know

Long or short→glycoproteins, TSH, ADH

Lipid derivatives and ones to know

Ones to know: steroids (estrogen, testosterone, calcitrol), eicosanoids like prostaglandins

What is special about steroids

The bond to plasma proteins which give them extended action and longer effect on the body

How do hormones travel in related to the blood

Either freely in blood (which attach to receptors) or attached to a carrier protein. But in both cases a hormone MUST attach to receptor

How are hormones recycled

Can be broken down by liver and kidney if not used

What stimuli control hormone secretion

Humoral stimuli, hormonal stimuli or neural stimuli

Humoral stimuli

Refers to changes in extra cellular environment (ECF)→for example insulin secretion

Hormonal stimuli

Changes in the levels of circulating hormones (hormone amount triggers hormone release)

Neural stimuli

Arrival of neurotransmitters at neuromuscular junctions which triggers nervous system (fight or flight), hypothalamus activation

Major functions affected by hormones

Mobilization of body defences

regulation of cellular metabolism

regulation of water, electrolyte and nutrient balance

Growth and development

Reproduction

What type of effects can hormones have on the other hormones

Permissive- Strengthens other hormone

Synergistic- works together with other hormone

Antagonistic-works in opposite to other hormone

What do hormones rely on to exert their effects

Target receptors in target organs

2 types of target receptors deemed by location

Extra cellular receptors-found on cell membrane

Intra cellular receptors-inside cell

Where can target receptors be found

May be on another endocrine organ causing inhibition or secretion of another hormone

In which ways can the number of target receptors by impacted

Up regulation and down regulation

What is up regulation

Process where lack of hormone leads to increase in receptors

What is down regulation

Where tissue becomes less responsive or turns off receptor due to an abundance of hormone (think type 2 diabetes)

Role of second messengers in endocrine response

While the hormones acts as the first messenger. Second messengers are needed to actually cause cell change

What are the second messengers needed and their functions

G proteins- link first and second messengers (stimulated receptor to cyclic AMP)

Cyclic AMP and calciuum- cyclic AMP acts as the second messengers to trigger change and desired cellular response to induce phosphorylation

Where is the hypothalamus and pituitary gland located, what connects them

Pituitary is a small gland located at the base of the brain that sits in sella turcica (bone depression in sphenoid)

Connected to hypothalamus by a thin connecting stalk called INFUNDIBULUM to provide constant communication between the two

Functions of the hypothalamus

Functions as an endocrine gland (produces OXYTOCIN AND ADH) - sends to post pit to be secreted

Secretes regulatory hormones that control activity of endocrine cells in ANTERIOR PITUITARY

Contains autonomic centres that controls endocrine cells o the adrenal medulla

Regulates functions of both pituitary lobes

Another name for the pituitary gland

Hypophysis

Functions of the pituitary gland, the lobes of the pituitary and the amount of hormones they secrete

Secretes 9 important hormones

Consists of 2 lobes

Posterior pituitary- 2 hormones

Anterior pituitary-7 hormones

Second name for posterior pituitary, type of tissue its composed of and hormones it secretes

NEUROHYPOPHYSIS- composed of neural tissue and secretes oxytocin and ADH

Another name for the anterior pituitary, tissue its composed of and hormones it secretes

ADENOHYPOPHYSIS, consists of glandular epithelial tissue and secretes: TSH, GH, FSH, LH, PRL,ACTH, MSH

What controls release of hormones from both lobes

Hypothalamus

What is ADH

Antidiuretic hormone or VASOPRESSIN which is released in response to hypothalamic osmoreceptors (blood pressure changes and solute concentration). MADE in hypothalamus SECRETED from POSTERIOR PITUITARY

Functions of ADH

PRESERVE WATER

Decreases urine production directly

Decreases sweating

Increases vasoconstriction

Impact of decreased ADH

Increased fluid loss and dehydration. Impacted by alcohol, caffeine ingestion, head trauma.

Oxytocin effects as a reproductive hormone in boys and girls

In men-causes contraction of sperm duct and ejection of sperm

In women-contraction of uterus (orgasm) which causes movement of sperm toward uterine tubes

Functions of oxytocin in labour and delivery and breast feeding

Contraction of uterus for delivery of infant and prevention of uterine bleeding

Causes a let down of milk from mammary glands (in fact suckling stimulates hormone)

What is SIADH

Syndrome of inappropriate ADH-often related to head trauma or tumours where TOO MUCH ADH causes a lot of water retention and high blood pressure

What is diabetes insipidus

TOO LITTLE ADH, causes lots of dilute urine production and causes extreme dehydration. (HAS NOTHING TO DO WITH INSULIN)

Name for overproduction of urine

Polyuria

Name for extreme thirst and hunger

Thirst-polydispia

Hunger-polyphasia

What is portal circulation in ant. Pit.

The idea that 2 capillary networks are connected. They provide efficient means of communication. Ensures all hypothalamic hormones entering portal vessels reach target cells in anterior lobe

process of portal circulation

Regulatory hormones from hypothalamus enter portal circulation→capillary circulation→fenestrated capillaries (very permeable) around endocrine cells of anterior pituitary→endocrine hormones released to blood stream→to systemic circulation via HYPOPHYSEAL veins

Which hormones regulate anterior pituitary hormone secretion

Hypothalamic releasing hormone (RH)

Hypothalamic inhibiting hormone (IH)

7 hormones secreted by the anterior pituitary

Thyroid stimulating hormone (TSH)

Adrenocorticotropic hormone (ACTH)

Growth hormone (GH)

Follicle stimulating hormone (FSH)

Luteinizing hormone (LH)

Prolactin (PRL)

Melanocyte stimulating hormone (MSH)

What is TSH describe negative feedback loop

Also known as a thyrotropin , creates a negative feedback loop in which hypothalamus stimulates pituitary which stimulates thyroid gland to secrete thyroid hormones.

As circulating concentrations of thyroid hormones rise, rates of TRH and TSH decline

What is ACTH, describe negative feedback loop

Also known as corticotropin stimulates release of steroid hormones by the adrenal cortex effects glucose metabolism such as cortisol

What are gonadotropins and which hormones are considered these

Regulate activity of the gonads (testes and ovaries). Stimulated by GnRH of the hypothalamus.

FSH and LH are gonadotropins

What is FSH

Follicle stimulating hormone: promotes sperm and egg maturation. Stopped by inhibin

What is LH

Luteinizing hormone- induces ovulation in females, promotes ovarian secretions of estrogen and progesterone. In males, stimulates release of testosterone and androgens

What is prolactin

Helps stimulate mammary gland development in females. Stimulates milk production by the mammary glands

What is the growth hormone, another name for it and what does it do

Somatotropin that stimulates cell growth and division by accelerating rate of protein synthesis in myocytes and chondrocytes

Follow path that growth hormone uses to stimulate cell growth

GH release→somatomedin hormones (insulin line growth factors released by liver)→increased uptake of amino acids→formation of proteins→increased cell synthesis

Main targets of GH

Bones, cartilage and skeletal muscles

Results of hyposecretion (Too little) of GH In kids and adults

In kids→Dwarfism

In adults→ decreased strength and bone mass

Results of hyper secretion (too much) of GH in kids and adults

In kids→gigantism

In adults→acromegaly (bones get thicker instead of longer)

How does thyroid hormone effect growth

Growth is stunted in kids with hypothyroidism

Hyper secretion does not cause excessive growth

How does insulin effect growth

Deficiency often blocks growth

Hyperinsulinism often spurs excessive growth

Androgens effect on growth

Plays a role in pubertal growth spurt, stimulates protein synthesis in many organs

thyrotropin releasing hormone

Stimulates secretion of TSH and PRL

Corticotropin releasing hormone

Stimulates release of ACTH

Where is thyroid gland

On anterior trachea, bow tie gland inferior to thyroid cartilage, not typically visible or felt through skin

What joins lobes of thyroid gland

Isthmus- bow tie

What are follicular cells

Cells bound to plasma proteins which are considered the functional cells of the thyroid that produce two iodine containing hormones

Thyroid hormones

Tetradiodothyronine (thyroxine or T4) -90% of thyroid

Tri-iodothyronine (T3)

Both depend on iodine molecules which can be obtained from our diet

What are C (clear) cells

Cells contained in thyroid that secrete peptide hormone CALCITONIN WHICH DECREASE CALCIUM IN BLOOD

Are thyroid hormones lipophilic or lipophobic

Lipophilic hormones

What type of effects do T3 and T4 have on the body

Impact rate of metabolism→by altering rate of protein synthesis in target cell.

Caloregenic→effect on metabolic rate and heat production

Thyroid hormones effect on other systems

Permissive to GH→aids growth

Nervous system growth and function

Sympathetic effect on cardiovascular and nervous system

Calcitonin role in body

Stimulates calcium excretion by kidneys and prevents calcium reaborbtion by GI tract. Decreases calcium levels in blood by putting it into bones and maintaining bone mass

What is hypothyroidism caused by

Failure of thyroid gland

secondary to TSH, TRH hormone deficiency

Not enough iodine in diet

Symptoms of hypothyroidism

Always tired, chilled, hair loss and weight gain

What is cretinism

Congenital disorder which effect mental and physical growth stemming from hypothyroidism from birth

What is myxedema

Face swells and characterized by thick hard skin on lower legs resulting from hypothyroidism

Treatment for hypothyroidism

Synthroid replacement therapy→synthetic supplement of thyroid hormones

Hyperthyroidism symptoms

High metabolism, weight loss, irritability

What is Graves’ disease

Autoimmune disorder which is the most common cause of hyperthyroidism BODY ATTACKS THYROID. And will aggressively produce thyroid stimulating immunoglobins and characterized by fluid retention in odd places (exophthalmos)

What causes goiters is it more related to hypo or hyper thyroidism

Occurs in both hyperthyroidism and hypothyroidism and primarily caused by low iodine levels

Where are your parathyroid glands

4 glands (2 on each side) embedded in posterior thyroid

Principle cells make PTH

What is the function of the parathyroid glands

Produce and secrete PTH in response to blood calcium levels

PTH effect on blood calcium levels

Increases calcium levels in blood by stimulating osteoclasts to break it down from bones. Though too much calcium in blood causes neurological damage

Where are your adrenal glands found

Sits on top of each kidney embedded in a capsule of fat which is important structures

Regions of adrenal glands

Adrenal cortex-outer portion that secretes corticosteroids

Adrenal cortex-inner portion that secretes catecholamines

Areas of the adrenal cortex

Zona glomerulosa- top layer, aldosterone

Zona fasciculata-middle layer, cortisol and cortisone

Zona reticularis-bottom layer, androgens

What are mineralocorticoids. Main hormone

Zona glomerulosa- steroid hormones that impact fluid and electrolyte balance primary hormone is aldosterone

Aldosterone effects and relationship with ADH

Decreases blood pressure. Promotes the reabsorption of Na sodium and in turn excretes potassium and hangs onto water as well.

Increased effect in presence of ADH

What are glucocorticoids and main hormone

Zona fasciculata-steroid hormones that impact glucose metabolism (increase fuel availability)

Main hormone is cortisol

ANTI INFLAMMATORY response and slows immune response

What stimulates cortisol secretion and how does it effect body

Stimulated by ACTH. Targets most cells to increase glucose synthesis and is sometimes activated in stress repsonses to make fuel more available

BODIES MAIN STRESS HORMONE

Cortisol effect on healing

If too much is secreted it can make your immune system more susceptible and in turn decreased healing rates and increases chances of getting sick

Androgens, where are they produces and what do they do

Zona reticularis- impact development of secondary sex characteristics and are estrogen and testosterone precursors

Diagnosis names for too little or too much cortisol

Too much→cushings disease (moon face)

Too little→addisons disease

During long term stress the constant cortisol stimulating messes with one’s homeostasis

What is mainly responsible for controlling hormone released from adrenal medulla

Sympathetic division of the autonomic nervous system

What hormones are produced by adrenal medulla

Epinephrine (80%) and norepinephrine

How do epinephrine and norepinephrine interact with plasma receptors

Bind to alpha and beta receptors on plasma membranes

Where is pineal gland found

Epithalamus

Primary function of pineal gland

Contains secretory cells called pinealocytes that synthesize melatonin

Its primary function is to influence circadian rhythm