Endocrine System Flashcards
In order for all cells in our body to survive, we maintain …
…a constant internal environment
Examples of homeostasis?
Glucose for energy
Gas exchange (oxygen / carbon dioxide)
Growth rate
Removal of waste
Temperature
Homeostasis is the process by which…
…we maintain this constant internal environment, irrespective of the changing environment around us.
Homeostasis is accomplished by carefully balancing…
…excretion, losses, and intake of nutrients and internal production and metabolic consumption.
Homeostasis involves…
…the interaction between our many body systems
The endocrine system is closely linked with the…
…reproductive system
Whats a hormone?
a chemical released by one part of the body, but regulates the activity of a cell in another part of the body
Hormones are usually dispersed by…
…the blood circulation
What are glands?
synthesises substances (such as hormones) for release
Whats a neurotransmitter?
chemical released by nerve impulse; usually released locally at a synapse
Whats a receptor?
- Target for hormone
- Target for neurotransmitter
The endocrine system releases hormones into …
…the circulation or into interstitial fluid.
Hormones released by the endocrine system travel in the…
…bloodstream
Hormones target distant cells/organs in the…
…body
ENdocrine system regulates…
…homeostasis
Glands of the Endocrine System:
Pituitary / Hypothalamus
Thyroid
Thymus (Immune System lecture)
Adrenal
Pancreas
Ovaries / Testes
In contrast, glands of the exocrine system…
…release fluids into the lumen or outside of the body, typically by way of a duct
the pancreas has both …
…endocrine and exocrine functions
Endocrine = insulin and glucagon into the bloodstream
Exocrine = digestive enzymes into the duodenum
Hormones released by endocrine glands travel around …
…the body, but only exert their effect on target cells
target cells have specific ________ for specific _________
target cells have specific receptors for specific hormones
adrenaline released by the …
…adrenal glands travels around the bloodstream and binds to adrenoceptors (adrenergic receptors)
when adrenaline meets β1 adrenoceptors in the heart
increases inotropy (force of contraction)
increases chronotropy (rate of contraction)
Whats intropy?
force of contraction
Whats chronotropy?
rate of contraction
Some hormones have many different …
…receptors
adrenaline has ___ different receptors
adrenaline has 5 different receptors
Adrenalines 5 receptors:
a1, a2, B1, B2, B3
Adrenalines different receptors…
…all exert different effects and are found in different tissues
Adrenalines different receptors are activated by…
….different concentrations of adrenaline
There are two types of hormones:
- Water soluble
- Lipid soluble
Water soluble examples:
- Adrenaline
- Noradrenaline
Water soluble hormones include…
…Include amine containing hormones
Lipid soluble hormones include…
…steroid hormones
Examples of lipid soluble hormones:
- Cortisol
- Aldosterone
- Androgens
- Oestrogens and progestogens
Lipid-Soluble Hormones are found…
…inside cells.
as the hormones are lipid soluble, they can …
…diffuse across cell membranes
Lipid soluble hrmones are known as…
…intracellular receptors and are insdie the target cell
Lipid soluble hormones usually in…
…the cytoplasm or nucleus
Lipid-Soluble Hormones forms a …
…a receptor/hormone complex
Lipid-Soluble Hormones alters…
…gene expression
- turns things on/off
Lipid-Soluble Hormones alter gene expression, turns things on/off, and affects…
…the target cells’ activity
Water soluble hormones bind to …
…target receptors outside cells
water soluble hormones cannot…
…diffuse across cell membranes
Water soluble hormones are known as…
…extracellular receptors (G protein-coupled receptor)
Water-Soluble Hormones are the…
…1st messenger
- binds to the receptor
What do 2nd messenger systems do?
1) cyclic adenosine monophosphate (cAMP)
2) cAMP activates protein kinases
3) protein kinases phosphroylate proteins
4) this either turns the protein on/off
5) affects the target cells’ activity
The Hypothalamus is the…
…master controller of the endocrine system
The hypothalamus is located…
…just below the thalamus of the brain.
Hypo means…
…under or below in greek
The hypothalamus is a major link between the …
…nervous and endocrine systems
The Hypothalamus is linked to the pituitry gland by the…
…infundibulum
Hormones from the Hypothalamus made by …
…the neurosecretory cells
Hormones from hypothalamus are packaged into…
…vesicles, which are released and diffuse into the plexus of the hypophyseal portal system
Hypothalamus produces…
…a variety of releasing / inhibiting hormones
Releasing hormones of the hypothalamus ?
CRH – Corticotropin Releasing Hormone
GHRH – Growth Hormone Releasing Hormone (Somatocrinin)
GnRH – Gonadotrophin Releasing Hormone
PRH – Prolactin Releasing Hormone (*thought to exist)
TRH – Thyrotrophin Releasing Hormone
Inhibiting hormones of the hypothalamus?
GHIH – Growth Hormone Inhibiting Hormone (Somatostatin)
Releasing and Inhibiting Hormones cause the anterior pituitary…
….to start/stop secreting hormones.
The Pituitary Gland is split into two parts:
1) Posterior Pituitary
2) Anterior Pituitary
Posterior Pituitary does not…
…synthesise hormones
Posterior Pituitary function?
Stores and releases two hormones made by the hypothalamus
What hormone does the posterior pituitary secrete?
- Vasopressin (Antidiuretic Hormone (ADH)) – urinary system
- Oxytocin – effects uterus and breasts
Anterior Pituitary gland Synthesises and secretes …
…a wide range of hormones
Anterior Pituitary Gland synthesises…
…releasing hormones.
Anterior Pituitary Gland five different…
…tropic cell types (1 – 5)
Anterior Pituitary Gland Secretes how many different hormones…
seven different hormones (I – VII)
The hormones released by Anterior Pituitary Gland?
1) Somatotrophs
- Secrete human Growth Hormone (hGH)
- cause cells to produce Insulin-like Growth Factors (IGF’s)
2) Thyrotrophs
- Secrete Thyroid Stimulating Hormone (TSH)
- controls the Thyroid Gland
3) Gonadotrophs
- Secrete Follicle Stimulating Hormone (FSH)
- Secrete Luteinising Hormone (LH)
4) Lactotrophs
- Secrete Prolactin
5) Corticotrophs
- Secrete Adrenocorticotrophic Hormone (ACTH)
- Secrete Melanocyte Stimulating Hormone (MSH)
How many adrenal glands?
2
Where are adrenal glands found?
Found on top of each kidney
Size of adrenal glands?
3-5 cm high
2-3 cm x 1 cm width
The Adrenal Glands differentiated into ___ regions?
Two regions
What are the two regions of the adrenal glands?
1) Cortex
2) Medulla
adrenal glands produces…
…hormones
Adrenal glands are under…
…central control
Adrenal hormones produced by hypothalamus ?
Hypothalamus - Corticotropin Releasing Hormone (CRH)
Adrenal hormones produced by pituitary ?
Pituitary - secretes Adrenocorticotrophic Hormone (ACTH)
Adrenal glands surrounded by a…
…capsule
Capsule made up of…
…connective tissue
Connective tissue / capsule of adrenal glands is highly…
…vascularised (blood supply)
The cortex and medulla of the adrenal gland secrete…
…hormones
The cortex of the adrenal gland comprises…
…80-90% of the gland
Medulla of adrenal glands comprises…
…10-20% of the gland.
Are adrenal glands essential for life?
Yes
Loss of the adrenal hormones leads to …
…death by dehydration/electrolyte imbalance
The cortex of the andrenal glands is subdivided into…
….3 zones
3 zones of the adrenal glands cortex?
1) Zona glomerulosa
2) Zona fasciculata
3) Zona reticularis
Zona glomerulosa:
- Outer zone
- Makes mineralocorticoids (Aldosterone)
Zona fasciculata:
- Middle zone
- Makes glucocorticoids (Cortisol)
Zona reticularis:
- Inner zone
- Weak androgens (dehydroepiandrosterone (DHEA))
Adrenal medulla contains…
…chromaffin cells.
Adrenal medulla are able to secrete…
- Adrenaline (A)
- Noradrenaline (NA)
Aldosterone is the major…
…mineralocorticoid
Aldosterone is produced by…
…the zona glomerulosa
Mineralocorticoid Hormones involved in…
…the excretion of H+ ions into the urine
Mineralocorticoid regulates…
…the acid / base balance of the blood
mineralocorticoid prevents …
…acidosis (blood pH < 7.35)
Main function of mineralcorticoids?
homeostasis of two mineral ions
- sodium (Na+)
- potassium (K+)
Mineralocorticoids regulate homeostasis of potassium and sodium which regulate…
- regulate blood volume
- regulate blood pressure
Homeostasis of sodium and potassium by mineralocorticoids is done through the…
…Renin-angiotensin-aldosterone (RAA) pathway
WHats ACE stand for?
Angiotensin Converting Enzyme (ACE)
Angiotensin Converting Enzyme (ACE) prevents…
…the conversion of Angiotensin I to Angiotensin II
What are Angiotensin Converting Enzyme (ACE) taken for?
hypertension
Examples of ACE drug?
Lisinopril / Enalapril
Lisinopril / Enalapril reduces…
…vasoconstriction of arterioles
Lisinopril / Enalapril treat…
…high blood pressure (hypertension)
Lisinopril / Enalapril reduce…
… death rate following myocardial infarction / heart failure
Lisinopril / Enalapril reduce load on…
… the heart and kidneys (in chronic kidney disease)
There are three glucocorticoids:
1) Cortisol (hydrocortisone) – 95%
2) Cortisone
3) Corticosterone
Glucocorticoids are produced by…
…zona fasiculata
glucocorticoids are very similar in structure to …
…aldosterone
- differ only in C=O and OH groups
Glucocorticoid function:
Regulate metabolism
Resistance to stress
Slide 28
What do glucocorticoids do?
Glucocorticoids are ____ hormones
Glucocorticoids are stress hormones
WHen are glucocorticoids released?
Released by the body to deal with ‘challenging’ situations
glucocorticoids promote…
…protein breakdown.
Glucocorticoids increase the rate of …
…protein breakdown in the body
- Usually in muscle fibres
Glucocorticoids liberate ___ into the bloodstream
Glucocorticoids liberate amino acids into the bloodstream
Amino acids may be used by body cells to …
- synthesise new proteins
- ATP production during prolonged hypoglycaemia (low blood sugar)
Slide 30
Slide 31
The additional glucose helps alleviate stress by …
…providing ATP to combat stresses
The additional glucose helps alleviate stress by providing ATP to combat stresses caused by:
Exercise
Fasting
Fright
Extremes of temperature
High altitude
Bleeding and Trauma
Infection
Disease
Surgery
slide 33
Glucocorticoid Drugs are used on …
…Psoriasis
Positive affect of Glucocorticoid Drugs on Psoriasis?
Topical corticosteroids reduce local inflammation
Hydrocortisone cream
Lessens the redness
Prevents itching
This is good
Negative affect of Glucocorticoid Drugs on Psoriasis?
They suppress the immune system
They can enable an infection to develop
Hide the signs of infection
This is bad
Positive affect of Glucocorticoid Drugs on Organ transplantation / autoimmune disease?
If you have a transplant, you must take drugs to prevent tissue rejection forever
Or suppress immune system in autoimmune disease
This will keep you alive
This is good
Negative affect of Glucocorticoid Drugs on Organ transplantation / autoimmune disease?
Getting the right balance between suppression / infection is very difficult
If the dose is not quite perfect
Very high risk of opportunistic infection
Kaposi sarcoma (tumour caused by Herpes virus)
This is bad
Cushing syndrome is caused by…
…high levels of exposure to cortisol
Causes of Cushing Syndrome:
1) Overstimulation of the adrenal cortex by excessive hormone release
- Corticotrophin releasing hormone (CRH)
- Adrenocorticotropic hormone (ACTH) - corticotrophin
2) Adrenalcorticol adenoma secreting cortisol
- Very common benign tumour (up to 30% of us have it at death)
- But only 15% actually secrete hormones
3) ACTH secreting tumours
- These are not pituitary tumours as you would expect
- Called small cell carcinomas
- Highly malignant cancer most commonly found in the lung
- Produce hormones including ACTH (or ADH)
4) Exposure to glucocorticoid drugs (iatrogenic or preventable)
- Usually through certain asthma / rheumatoid arthritis / immunosuppression medications
Symptoms of Cushing Syndrome:
- Excessive gluconeogenesis
- Elevated blood glucose
- Glucose gets deposited as fat
- Moon face
- Buffalo hump
- Loss of lean muscle
- Weakness
What does treatment of Cushing Syndrome depend on?
- Treatment depends on the cause
What is DHEA?
Dehydroepiandrosterone
DHEA produced by…
…zona reticularis
Prior to puberty ____ is the major androgen in males
Prior to puberty Dehydroepiandrosterone (DHEA) is the major androgen in males
- Then, testosterone takes over.
Functions of Adrenal Androgens in males?
Pubic hair development, but insignificant after puberty
Functions of Adrenal Androgens in females?
- Sex drive (libido)
- Converted to oestrogen (female sex hormone) by other tissue in the body
- After menopause, they will be the only source of oestrogen
Slide 39
The adrenal medulla is a modified what?
a modified sympathetic ganglion
What does the adrenal medulla lack?
Axons
How do cells grow in blood vessels?
The cells grow in clusters around blood vessels (chromaffin cells)
Adrenaline is released as…
… a hormone
The medulla is innervated by the…
…ANS
The medulla is innervated by the ANS and can quickly …
…stimulate catecholamine secretion
The adrenal medulla is the innermost part of the…
…adrenal glands
What does the adrenal medulla produce?
Catechoolamines (epinephrine and norepinephrine / adrenaline and noradrenaline)
Percentage amounts of catecholamines produced?
Adrenaline (epinephrine) - (80%)
Noradrenaline (Norepinephrine) – (20%)
In the adrenal glands catecholamines are …
… hormones
In the adrenal glands catecholamines are hormones.
However in the CNS they function as…
… neurotransmitters.
Function of Catecholamine hormones?
– Produce the ‘Fight or Flight’ response
– Stressful situations
– Exercise
Effects of catecholamines?
- Increase force and rate of heart contraction
- Increase blood pressure
- Dilate airways – B2 adrenoceptor
- Increase blood sugar by breaking down glycogen
- Increase blood flow to the muscles / liver.
Why are catecholamines important?
- Heart is primed for activity
- Extra glucose for muscles and lots of air to the lungs
Examples of catecholamine drugs?
1) Ventolin
2) Beta blockers
What is ventolin?
Asthma inhaler
What does ventolin contain?
salbutamol
What kind of agonist in ventolin?
B2 adrenoceptor agonist
Ventolin specifically affects receptors in…
…the airways
How does ventolin make it easier to breathe?
Dilates airways making it easier to breathe
How are catecholamines used in cardiac arrest?
- Administer adrenaline / noradrenaline
- CPR
- Defibrillation
- Increases heart rate
- Increases force of contraction
- Helps restart the heart
Examples of catecholamine drugs?
- Propranolol (b1 and b2 antagonist)
- Atenolol (b1 antagonist)
What are catecholamine drugs used to treat?
- High blood pressure
- Tachycardia
- Angina
- Glaucoma
What can beta blockers also be used to help calm?
Performance anxiety
How do beta blockers help with performance anxiety?
Prevents:
- Dry mouth
- Increased heart rate
- Butterflies in the stomach
- Tremor
- Banned in sports (not useful in all sports)
How many Gonads do males and females have?
Males have two and females have two
What are the Gonads in males?
Testes
What are the Gonads in females?
Ovaries
Like many other glands, the gonads are under…
… central control by the hypothalamus.
What does the hypothalamus release which helps to control the gonads?
Secretes Gonadotrophin Releasing Hormone (GnRH)
What does the pituitary gland release which helps to control the gonads?
Secretes Luteinising Hormone (LH) and Follicle Stimulate Hormone (FSH)
Whats LH?
Luteinising Hormone
Whats FSH?
Follicle Stimulating Hormone
What is the primary trigger of puberty?
Gonadotrophin Releasing Hormone (GnRH)
Gonadotrophin Releasing Hormone (GnRH) is produced by…
…Hypothalamus gland
Gonadotrophin Releasing Hormone (GnRH) has a […] release
Gonadotrophin Releasing Hormone (GnRH) has a pulsatile release
Gonadotrophin Releasing Hormone (GnRH) causes the release of …
…. Gonadotrophins
Gonadotrophins have a […] release.
Gonadotrophins have a pulsatile release.
In females, Luteinising Hormone (LH) acts on…
… Theca cells
Theca cells surround the …
…follicles
What do theca cells synthesise?
androgens
Oestrogens are synthesised
from …
… androgens
In females, FSH stimulates…
… immature ovarian follicles to develop
n females, FSH stimulates immature ovarian follicles to develop.
Then the follicles…
…. mature.
Follicle means what in latin?
means nest in latin
The process of egg development is known as?
Oogenesis
Whats Oogenesis?
Egg development
Whats oestrogen responsible for in females?
- Growth of breasts
- Growth of pubic hair
- Bone growth (growth spurts, widening of the hips)
- More subcutaneous fat (hips, thighs, and buttocks)
- Growth of the uterus
- Proliferation of the endometrium (menstrual cycle, monthly development and release of 1 egg, place for implantation (endometrium))
Whats endometrium?
place for implantation
In males, LH acts on…
…Leydig cells
In males, LH acts of the Leydig cells which synthesises what?
synthesises testosterone (increases testosterone levels)
In males, FSH stimulates…
… follicles
In males, FSH stimulates follicles and acts on the…
…Sertoli cells
In males, FSH acts on the Sertoli cells which stimulates…
… primary spermatocytes to undergo
the first division of meiosis, forming secondary spermatocytes.
FSH is a key hormone in the process of…
…spermatogenesis (sperm production)
Whats spermatogenesis?
sperm production
Effects of testosterone in males?
- Enlargement of the larynx & laryngeal muscle
- Enlargement of the genitalia
- Growth of pubic hair
- Growth of facial hair
- Bone growth (growth spurt, become broader in the shoulders)
- Fusing of epiphyseal plates
What are epiphyseal plates?
- hyaline cartilage plate in the metaphysis
- found at each end of the long bones