Types of hormones, pituitary gland and hypothalamus role

What is the endocrine system?

Coordinates the function of tissues, organs and systems (same role as nervous system) through the release of hormones

What are hormones

Chemicals messengers which travel through the blood and are released by endocrine glands.
They're specific to their target as target cells must contain receptors for hormone
Have a widespread effect and act more slowly than nervous responses.
Hormones exert their influence by changing the activity of enzymes or their concentration

What do hormones do?

• activate certain genes in the nucleus so that a particular enzyme or structural protein is produced
• change the shape or structure of an enzyme so that it is turned 'on' or 'off'
• change the rate of production of an enzyme or structural protein by changing the rate of transcription or translation during protein production.

What are steriod hormone (lipid-soluble)?

Can dissolve in fats but not in water (so it can't diffuse into blood as it consists mostly of water).
Attach to carrier proteins to travel through blood
Can diffuse easily into the lipid bilayer of the membrane
-When it enters the cell it changes protein synthesis (gene expression and the proteins made by the cell)
Longer lasting but slower response/activation

What do steriod hormone s form?

When it enters cells, it combines iwth/ activates intracellular receptor protein in the cytoplasm or nucleus. This then forms the hormone-receptor complex which activates genes controlling the formation of particular proteins. It does this by binding to the promoter section of a certain gene, stimulating (or inhibiting) transcription

What does steroid hormone do?

Enters the cell and influences/ changes protein synthesis.
Changes gene expression, meaning it tells the cell to make new proteins, leading it to be longer-lasting

What are steriod (lipid-soluble)?

-Oestrogen
-Testosterone (sterone so steriod hormone)
-Cortisol
-Aldosterone (sterone so steriod hormone)
TACO

What is the flow chart for sterioid (lipid-soluble) hormone?

Released into the bloodstream --> Binds to carrier proteins --> Enables sterioid hormones to travel in the bloodstream (since they're lipid soluble) --> Reaches the target cell and seperates from transport protein --> Diffuses across the lipid bilayer of the membrane --> Binds to and activates the intercellular receptor in cytoplasm or nucleus --> Forms a hormone-receptor complex --> Complex enters the nucleus (if its not already there --> Binds to the promoter region of a specific gene --> This stimulates or inhibits transcription of those genes--> Therefore affects protein synthesis (causes changes in gene expression which leads to changes in cell activity and function)

What are peptide hormone (water-soluble)?

It can travel freely through the blood because its water soluble
However, it is repelled by the phospholipid bilayer so it needs to bind to a receptor protein
Once it binds to it, it activates secondary messenger into the cell
-They influence enzymes to work quicker or slower
Happens faster but can't be stored

What does peptide hormone do?

Impact the overall cell metabolism of the cell through enzymes activity.
It causes temporary changes in gene expression or by turning proteins on or off or

What is the flow chart for peptide hormones?

Water soluble means they can travel freely through bloodstream --> Reaches target cell --> Repelled by the phospholipid bilayer because its not lipid soluble --> Attaches to receptor proteins in the membrane of the target cell --> Combination of the hormone and receptor activates secondary messenger in the cytoplasm --> The secondary messenger diffuses through the cytoplasm and it activates or inhibits particular enzymes --> Influences enzymes to work quicker or slower --> Enzyme activity changes metabolism and cause temporary changes in gene expression

What is the differences and similarities between steroid and lipid soluble?

Solubility:
-Steroid: Lipid-soluble
-Peptide: Water-soluble
Receptors:
-Steroid: Inside cell, cytoplasm's/ organelles
-Pepide: On the cell surace
Travel through blood:
-Steroid: Attached to carrier proteins
-Peptide: Freely transported
Secondary messenger:
-Steroid: Not required (instead it activates an intercellular receptor inside the cytoplasm
-Peptide: Required (activates inside the cytoplasm)
Action:
-Steroid: Longer lasting/ can be stored
-Peptide: Shorter/ can't be stored
Result:
-Steroid: Affects protein synthesis
-Peptide: Change enzyme activity

What is saturation?

Once all the receptor molecules are occupied by hormone molecules, the addition of more hormones does not produce any greater effect.

Why is there variation in the sensitivities of cells to hormones and other substances?

Different cells have different types and numbers of receptor protein

What is enzyme amplification?

A series of chemical reactions in which the product of one step is an enzyme that produces an even greater number of product molecules at the next step

What is mode of action?

How it effects/ changes something (how it works)

Where are pituitary galnds located

Located in hypothalamus
Anterior front (slightly forward of posterior pituitary gland
Posterior back

What is the pituitary gland?

Known as the master gland and regulates many bodily functions like growth, sexual development, metabolism.

What hormones are secreted by the anterior pituitary galnd?

Follicle stimulating hormone (FSH)
Lutenising hormone (LH)
Human growth hormone (HGH)
Prolactin
Thyroid stimulating hormone (TSH)
Adrenocorticotropic hormone (ACTH)

What is follicle stimulating hormone?

Target:
-Ovaries
-Tetes
Function:
-Stimulates the growth and maturation of ovarian follicles (which contain the eggs) in the ovaries.
-Stimulate the production/ maturation of sperm through maintaining spermatogenesis.

What is luteinizing hormone?

Target:
-Ovaries
-Tetes
Function:
-Stimulates the growth and maturation of ovarian follicles (which contain the eggs) in the ovaries to the corpus luteum
-Stimulates release of steroid hormones in females (corpus luteum produces some oestrogen)
-Stimulate interstitial cells to secrete the male sex hormone, testosterone (steriod hormone)

What is the human growth hormone?

Target:
-Cells in muscle, bone and liver
Function:
-Stimulates body growth (growth of the skeleton) through aiding in the building of muscles and bones. It increases amino acid uptake by cells (increases protein synthesis and maintain organ size)

What are prolactin?

Target:
-Mammary glands
Function:
-Initiates and maintains milk production
-Develops mammary glands in the breast tissue

What are thyroid stimulating hormone (TSH)?

Tagert:
-Thyroid galnds
Function:
-Stimulates the production and release of thryoxine and tri-iodothyronine from thryoid glands

What are adrenocorticotropic hormone (ACTH)?

Target
Adrenal cortex
Function
Stimulates the production and release of hormones from the adrenal cortex (cortisol and aldosterone)

What are the hormones in the posterior gland?

Oxytocin and anti-diuretic

What is oxytocin?

Target:
-Mammary glands/ uterus
Function:
-Stimulates the contraction of muscles in the uterus during childbirth
-Stimulates the relaxation of the muscles in the cervix during childbirth
-Stimulates contractions of cells in the mammary glands causing the release of milk during breastfeeding

What is anti-diuretic hormone (ADH)?

Target:
-Tubules in nephron (Distal convoluted tubules and collecting duct)
Function:
-Causes increase in water absorption from urine in the Tubules by increasing permeability of Tubules (osmoregulation).
-Causes kidneys to remove water from urine and return that water to the blood stream (increase rebasorption of water from kidneys) heloing to regulate water balance.
-This lowers volume of urine produced

What does the hypothalamus do?

Maintains homostasis by controlling many body functions through the control of the pituitary gland. It releases factors that stimulate or inhibit the secretion of hormones. These factors travel through blood vessels and affect the pituitary gland
-Inhibiting factor slow down the secretion of hormones
-Releasing factors stimulate the secretion of hormones

How does the hypothalamus determine the release of hormones in the anterior pituitary gland?

The hypothalamis secretes inhibiting or releasing factors which passes down the local capillary network (through the hypothalamic-hypophyseal portal system which connect the hypotalamus with the anterior lobe). Once it passes down to the anterior pituitary gland the hormones are then released via a chemical/ hormonal stimulation.

What hormones does the hypothalamus produce?

Produces oxytocine and ADH which are stored in the posterior pituitary gland. These hormones then are transported down the axons and stored in the posterior lobe and then released via nervous stimulation into the blodostream by posterior

How does the hypothalamus produce hormones for the posterior pituitary gland (faster than anterior because of nerve impulse and oxytocin and ADH are immediate)?

Hormones of the posterior pituitary glands are produce in the hypothalamus --> Passed down in vesicles through axons to the posterior pituitary --> Stored in axon terminals (neurosecretory cells- moves chemicals + electrical chemical) within the posterior pituitary gland --> Hypothalamus then sends a nerve impulse to the posterior pituitary gland to secrete the hormone (release into blood)

What role does the hypothalamus do in the anterior pituitary galnd?

Hypothalamus producduces and released inhibiting or releasing factors (hormones) --> Passed down the local capillary network (through the hypothalamic-hypophyseal portal system which connect the hypotalamus with the anterior lobe) --> Passes into the anterior pituitary gland --> Stimulates the release of hormones from the anterior pituitary gland into the blood