Overview of the Endocrine System

Summary

This video script offers a comprehensive overview of the endocrine system, detailing its role as a communication network controlling physiological activities. It describes how hormones, produced by glands and cells, regulate various body functions. The script explains the hypothalamus as the master regulator, controlling the pituitary gland and other glands, and outlines the functions of hormones such as thyroid-stimulating hormone, cortisol, and insulin. It also touches on the roles of the adrenal, thyroid, and reproductive glands, emphasizing the system's importance in maintaining homeostasis.

Takeaways

• 🔬 The endocrine system is a network of glands and cells that produce hormones which regulate physiological processes throughout the body.
• 🏃‍♂️ Unlike the nervous system, the endocrine system works more slowly and its effects can last from hours to weeks.
• 🧠 The hypothalamus, located at the base of the brain, is the control center of the endocrine system and produces hormones that regulate other glands.
• 🔋 The hypothalamus releases hormones that control the anterior pituitary gland through the bloodstream and the posterior pituitary gland through nerves.
• 🌡️ Thyroid-stimulating hormone (TSH), released by the anterior pituitary, stimulates the thyroid gland to produce T3 and T4, which are crucial for metabolism, development, and catecholamine release.
• 🚀 Adrenocorticotropic hormone (ACTH), also released by the anterior pituitary, prompts the adrenal cortex to produce cortisol, which increases blood glucose and stimulates the fight-or-flight response.
• 💧 Anti-diuretic hormone (ADH), stored in the posterior pituitary, helps maintain hydration by reducing urine production during dehydration.
• 💊 The parathyroid gland releases parathyroid hormone to increase blood calcium levels, counteracting the effects of calcitonin, which decreases calcium.
• 🥖 The pancreas has both endocrine and exocrine functions, releasing insulin to lower blood glucose and glucagon to raise it when needed.
• 🌟 The kidneys play a role in the endocrine system by releasing hormones like renin, which helps regulate blood pressure, and erythropoietin, which stimulates red blood cell production.

Q & A

What is the primary function of the endocrine system?

The endocrine system is responsible for producing and releasing hormones that act as chemical messengers to regulate physiological activities throughout the body.

How does the endocrine system differ from the nervous system?

The endocrine system is slower and less direct than the nervous system, as it relies on hormones that enter the bloodstream and travel to distant areas of the body, whereas the nervous system is fast, direct, and usually short-acting.

What is the role of the hypothalamus in the endocrine system?

The hypothalamus acts as the master regulator or control center of the endocrine system, producing hormones that control and regulate many other tissues of the body.

What are the five important hormones produced by the hypothalamus?

The hypothalamus produces thyrotropin-releasing hormone, corticotropin-releasing hormone, growth hormone-releasing hormone, prolactin-releasing hormone, and gonadotropin-releasing hormone.

How does the hypothalamus communicate with the anterior and posterior pituitary glands?

The hypothalamus communicates with the anterior pituitary gland through a blood supply, releasing hormones that travel through the blood to stimulate the anterior pituitary to release its hormones. The posterior pituitary gland is connected to the hypothalamus through nerves, allowing the hypothalamus to send a nervous signal to stimulate hormone release.

What are the main hormones released by the anterior pituitary gland?

The anterior pituitary gland releases thyroid-stimulating hormone, adrenocorticotropic hormone, growth hormone, prolactin, and gonadotropins (luteinizing hormone and follicle-stimulating hormone).

What are the functions of thyroid hormones T3 and T4?

T3 and T4 play an extremely important role in metabolism, development, and catecholamine release. T3 is the most active thyroid hormone, with a ratio of approximately 80% T3 to 20% T4.

What is the role of cortisol released by the adrenal cortex?

Cortisol increases blood glucose, suppresses the immune system, and stimulates the fight or flight response.

How does aldosterone affect blood pressure and hydration?

Aldosterone increases the reabsorption of salt in the kidneys, leading to increased blood volume and blood pressure, and helps maintain hydration.

What are the functions of growth hormone released by the anterior pituitary gland?

Growth hormone stimulates growth, increases protein synthesis, and enhances metabolic processes.

What are the roles of luteinizing hormone and follicle-stimulating hormone in the reproductive system?

Luteinizing hormone stimulates progesterone production, ovulation, and testosterone production in males. Follicle-stimulating hormone stimulates follicle maturation and estrogen production in females, and sperm production in males.

Outlines

00:00

🧠 Introduction to the Endocrine System

Dr. Mike introduces the endocrine system, a network of glands and cells that produce hormones. These hormones act as chemical messengers in the bloodstream, affecting distant parts of the body. Unlike the nervous system, the endocrine system works slowly and has long-lasting effects. The video will explore key glands and hormones, starting with the hypothalamus in the brain, which acts as the master regulator of the endocrine system. The hypothalamus produces hormones that control other glands, including the pituitary gland, which itself has anterior and posterior lobes. The hypothalamus communicates with the anterior pituitary through blood vessels and with the posterior pituitary through nerves. The hypothalamus releases five key hormones that regulate various aspects of the endocrine system.

05:03

🔍 Hormones and Their Functions

The video discusses the hormones released by the hypothalamus and their effects on the body. Thyrotropin-releasing hormone stimulates the release of thyroid-stimulating hormone, which in turn triggers the thyroid gland to release T3 and T4 hormones, crucial for metabolism, development, and catecholamine release. Corticotropin-releasing hormone prompts the release of adrenocorticotropic hormone (ACTH), which travels to the adrenal gland to stimulate the release of cortisol, aldosterone, and androgens. These hormones are involved in blood glucose regulation, immune suppression, and the fight-or-flight response. Growth hormone, released by the anterior pituitary, stimulates growth and metabolic processes. Prolactin, also from the anterior pituitary, increases milk production in response to prolactin-releasing hormone from the hypothalamus.

10:05

🌟 Gonadotropins and Posterior Pituitary Hormones

The video explains the role of gonadotropins, which include luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH stimulates progesterone production and ovulation in females, while FSH stimulates follicle maturation and estrogen production. In males, LH stimulates testosterone production, and FSH stimulates sperm production. The posterior pituitary releases oxytocin, which is involved in uterine contractions, milk ejection, and social bonding, and antidiuretic hormone (ADH), which conserves water in the body by reducing urine production during dehydration.

15:07

🩺 Other Endocrine Glands and Their Functions

The video concludes by discussing other endocrine glands. The parathyroid gland releases parathyroid hormone, which increases blood calcium levels, opposing the action of calcitonin from the thyroid. The kidneys release hormones such as renin, which works with aldosterone to increase blood pressure and blood volume, and erythropoietin, which stimulates red blood cell production. The pancreas has both endocrine and exocrine functions, releasing insulin to lower blood glucose levels and glucagon to raise them. The endocrine system, through these hormones and glands, maintains the body's homeostasis and overall function.

Keywords

💡Endocrine System

The endocrine system is a network of glands and cells that produce hormones, which are chemicals that travel through the bloodstream to regulate physiological processes throughout the body. In the video, the endocrine system is described as a communication network similar to the nervous system but with a slower response time and longer-lasting effects. It plays a crucial role in maintaining homeostasis and controlling various body functions.

💡Hormones

Hormones are chemical messengers that are produced by the endocrine glands and transported through the bloodstream to target cells or organs where they exert their effects. In the context of the video, hormones are essential for regulating metabolism, growth, development, and reproductive functions, among others.

💡Hypothalamus

The hypothalamus is a region at the base of the brain that links the nervous system to the endocrine system. It is described in the video as the 'master regulator' or 'control center' of the endocrine system. It produces hormones that regulate other glands and tissues, such as thyrotropin-releasing hormone and corticotropin-releasing hormone.

💡Pituitary Gland

The pituitary gland, often referred to as the 'master gland,' is an endocrine gland located beneath the hypothalamus. It is divided into anterior and posterior lobes, each producing different hormones. In the video, it is mentioned that the hypothalamus communicates with the pituitary gland to regulate hormone release.

💡Thyroid Gland

The thyroid gland is an endocrine gland that wraps around the trachea and produces hormones that regulate metabolism. The video explains that the thyroid gland produces T3 (tri-iodo thyronine) and T4 (thyroxine), which are crucial for metabolism, development, and catecholamine release.

💡Adrenal Gland

The adrenal glands are endocrine glands that sit on top of the kidneys and produce hormones like cortisol and adrenaline. The video describes how the adrenal cortex releases cortisol in response to adrenocorticotropic hormone (ACTH), which is produced by the anterior pituitary gland.

💡Catecholamines

Catecholamines are a class of hormones and neurotransmitters that include adrenaline, noradrenaline, and dopamine. In the video, catecholamines are mentioned as being released by the thyroid hormones and are involved in the 'fight or flight' response.

💡Gonadotropins

Gonadotropins are hormones that stimulate the gonads (ovaries in females and testes in males). The video explains that luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are gonadotropins that regulate the production of sex hormones and gametes.

💡Prolactin

Prolactin is a hormone produced by the anterior pituitary gland that stimulates milk production in mammals. The video mentions that prolactin is released in response to prolactin-releasing hormone from the hypothalamus.

💡Parathyroid Gland

The parathyroid glands are endocrine glands that are located behind the thyroid gland. They produce parathyroid hormone, which increases blood calcium levels. The video contrasts the function of parathyroid hormone with that of calcitonin, which decreases blood calcium levels.

💡Homeostasis

Homeostasis refers to the maintenance of a stable internal environment in the body. The video emphasizes that the endocrine system, through the actions of various hormones, plays a vital role in maintaining homeostasis by regulating body functions such as blood glucose levels, blood pressure, and calcium levels.

Highlights

The endocrine system is a collection of cells and glands that produce and release hormones.

Hormones are chemicals that travel through the bloodstream to distant areas of the body.

The endocrine system is a communication network similar to the nervous system but with a slower response.

The hypothalamus is the master regulator or control center of the endocrine system.

The hypothalamus produces five important hormones to control the endocrine system.

The pituitary gland is an extension of the hypothalamus that produces and releases hormones.

The hypothalamus communicates with the anterior pituitary gland through a blood supply.

The posterior pituitary gland is connected to the hypothalamus through nerves.

The anterior pituitary releases hormones such as thyroid stimulating hormone and adrenocorticotropic hormone.

The thyroid produces hormones T3 and T4, which play a role in metabolism, development, and catecholamine release.

Calcitonin decreases the amount of calcium in the bloodstream.

Adrenocorticotropic hormone stimulates the release of cortisol, aldosterone, and androgens from the adrenal cortex.

Cortisol increases blood glucose and stimulates the fight or flight response.

Aldosterone increases blood volume and blood pressure by increasing salt reabsorption.

The adrenal medulla releases noradrenaline and adrenaline.

Growth hormone stimulates growth and increases protein synthesis.

Prolactin stimulates milk production in response to prolactin releasing hormone from the hypothalamus.

Gonadotropins stimulate the production of sex hormones and support reproduction.

The parathyroid gland releases parathyroid hormone to increase blood calcium levels.

The kidneys release hormones such as renin and erythropoietin to control blood pressure and red blood cell production.

The pancreas releases insulin and glucagon to regulate blood glucose levels.

Transcripts

hi everyone dr mike here in this video

we're going to take a look at the

endocrine system

[Music]

now the endocrine system is a collection

of cells and glands that produce and

release

hormones these hormones are just

chemicals that jump into the bloodstream

and have their effect in distant areas

of the body

now it's a communication network similar

to the nervous system that controls

physiological activity but it's a little

bit different it's different in the

sense that the nervous system

is very fast it's very direct and

usually it's short acting

the endocrine system is the opposite so

it's quite slow to have its effect

it isn't direct because it jumps into

the bloodstream and travels to very

distant areas of the body

and it can last a long time some

hormones when they're released

can have their effects that last hours

to days to sometimes

weeks so in this video we're going to go

through some of the important

cells or glands that produce and release

hormones and go through

what these hormones are and have a quick

look at their activity or function in

the body

we're going to do this a top to toe

mechanism start at the top and move our

way down so to begin we need to start at

the brain

specifically at the base of the brain

there's something called the

hypothalamus which is telling you

it sits below the thalamus this is the

hypothalamus it sits here

we've taken it across here here's the

hypothalamus and you can see that

there's

an extension of the hypothalamus that

has two lobes to it or two parts

this is called the pituitary gland and

that's another endocrine

tissue or gland that itself produces and

releases hormones

the hypothalamus produces another a

number of hormones

that has its effect to control and

regulate

the endocrine system of many other

tissues of the body so we call the

hypothalamus

the master regulator or the control

center of the endocrine system

now five important hormones that the

hypothalamus produces

and releases to control many other

aspects of the endocrine system

these hormones are thyrotropin releasing

hormone

corticotropin releasing hormone growth

hormone releasing hormone

prolactin releasing hormone and

gonadotropin releasing hormone so a

couple of points here

releasing hormone tells you it goes

somewhere else

to release a hormone all right makes

sense also

tropon as a suffix tropin sitting at the

end of the word

if you see a hormone with tropon as a

suffix it means it's going to go to

another tissue of the body to tell it to

release another hormone all right

so how does this work well the

hypothalamus

talks to both aspects of the pituitary

gland

posterior and anterior but interestingly

the anterior is connected to the

hypothalamus through a blood supply

which means the only way the

hypothalamus can talk to it is it

releases hormones and they travel

through this blood supply to tell the

anterior pituitary gland to release its

hormones

the posterior pituitary gland is

connected to the hypothalamus through

nerves which means the hypothalamus

doesn't need to release hormones to tell

the posterior to do it

it just sends a nervous signal down to

tell the posterior to release

hormones all right these hormones

that are named here that the

hypothalamus produces

moves through the blood supply to the

anterior pituitary

to tell the anterior pituitary to

release a number of hormones

number one the hormone that is told to

be released from the anterior pituitary

gland

is thyroid stimulating hormone

the second hormone now there's no

particular order i'm just

ordering it here for ease basically but

there's no particular order

but the second hormone that's released

is adreno

cortico tropic

hormone the third is growth hormone

the fourth is prolactin

and the fifth is the gonadotropin

gonadotropins and there's two

gonadotropins you need to know

that is luteinizing hormone

and follicle

stimulating hormone

all right what happens

thyrotropin-releasing hormone released

from the hypothalamus

stimulates the release of thyroid

stimulating hormone

this is a hormone that now jumps into

the bloodstream and goes to the

thyroid to tell it to release its

hormone so let's have a look at this

number one tells that one to be released

that jumps into the bloodstream

goes to the thyroid so let's have a look

at the thyroid quickly

the thyroid is endocrine tissue that

hugs the front of your trachea

your windpipe what you'll find is that

the thyroid produces a couple of

important hormones it produces

t3 which is also known as

tri-iodo thyronine

and t4 which is known as thyroxine

interestingly t4

well most of it is turned into t3 t3 is

the most active

thyroid hormone so when we talk about

thyroid hormones we're talking about t3

predominantly 80 percent 20 that's the

ratio that we see here

there's another hormone that's released

by the thyroid called calcitonin

calcitonin talk about that in a sec

so thyrotropin releasing hormones

released by the hypothalamus travels

down this blood supply tells the

anterior pituitary to release thyroid

stimulating hormone

that jumps into the bloodstream tells

the thyroid to release t3 and t4

what do they do they play an extremely

important role

in metabolism

development

and catecholamine release

what's catecholamine catecholamines are

neurotransmitters these are things and

hormones are things like

adrenaline or noradrenaline or

epinephrine norepinephrine for example

that's what thyroid hormones do

calcitonin

is interesting what calcitonin does is

it decreases the amount of calcium in

the bloodstream

if there's too much calcium in the

bloodstream calcitonin

drops that calcium down helps us

reabsorb and hold on to that calcium

predominantly in our bony tissue that's

the thyroid hormone

what happens when corticotropin

releasing hormone is released from the

hypothalamus traveling through this

blood supply stimulates

adrenocorticotropic hormone

to be released also known as acth

that jumps into the bloodstream and

travels to adreno

adrenal adrenal gland cortico the

outside of the adrenal gland

tropic is it's telling it to release

another hormone

so it's all in the name let's go to the

adrenal gland now

the adrenal gland now if we look at the

adrenal gland you've got the cortex

which is the outside of it like the

shell

of it and you've got the medulla

which is the inside they release

different hormones so for example

adrenocorticotropic hormone will go to

the cortex more specifically

and release cortisol

and it will release

aldosterone and androgens

we'll leave androgens out but androgens

which are male sex hormones

so cortisol what does cortisol do

cortisol

increases blood glucose

cortisol also suppresses the immune

system

and cortisol also stimulates our fight

or flight

response really importantly what does

aldosterone do

aldosterone increases our reabsorption

of salt what does that mean

increases our reabsorption of salt

aldosterone travels

to our kidneys and tells our kidneys

don't pee out that salt or that sodium

keep it in the blood this is important

because wherever sodium goes

water follows so if we reabsorb more

sodium into our bloodstream

water follows and it increases our blood

volume which means it increases our

blood pressure aldosterone helps

increase blood pressure increase

blood volume and also maintain hydration

really important

what about the medulla well the medulla

isn't stimulated

very strongly at all by acth but the

hormones that are released by the inside

of the adrenal gland are predominantly

noradrenaline

and adrenaline what are they that's

norepinephrine and epinephrine all right

what else growth hormone okay growth

hormone is released

from the anterior pituitary gland and

that stimulates

growth unsurprisingly growth hormone

stimulates growth

increase growth things like

increased protein synthesis

for example

increases growth increases metabolic

processes

all right prolactin prolactin lactin

lactation

the production of breast milk

pro-lactation so

prolactin which is released by the

anterior pituitary gland in response to

prolactin releasing hormone from the

hypothalamus

that stimulates milk production

increases milk production

now it's not milk ejection which is let

down through breastfeeding

that's oxytocin which i'm going to talk

about in a second

and then the gonadotropins the

gonadotropins so tropon it's going to

the gonad so for the females the ovaries

for the males the testes and these

hormones go to both

for females goes to the ovaries for

males go to the testes and has their

function

what is their function all right

luteinizing hormone let's look at

the ovaries first

what luteinizing hormone does is

it stimulates progesterone

it also stimulates ovulation

ovulation and progesterone

follicle stimulating hormone stimulates

follicle maturation

what's that mean in the female

reproductive cycle

you've got these immature primordial

follicles they ultimately turn into an

oocyte or an egg that gets released so

fsh released by the hypothalamus

well specifically the anterior pituitary

gland stimulates these follicles to

start

moving through the process to go towards

the release of a mature

egg the actual release of the egg is

luteinizing hormone

so follicle maturation also leads to

estrogen

so two really important hormones that

are released here in response to lh

is progesterone and fsh estrogen

what about in the testes let's have a

look for males in the testes

well luteinizing hormone stimulates a

certain type of cells called

latex cells and what they produce is

testosterone

that's the hormone produced here

testosterone

what about follicle stimulating hormone

well there's no follicles in males

but what it does is it stimulates a

certain type of cells in the testes

called setoli cells so both ladies and

setoli cells are in the testes

lady produces testosterone so tole

produces something called

androgen binding protein and both of

these

bind together

to promote sperm production so

unsurprisingly the ovaries

luteinizing hormone follicle stimulating

hormone produced hormones here

and what this does is it leads to

uterus preparation

so if you're preparing the uterus and

producing sperm

both of these things coming together is

going to support reproduction

that's going through the anterior

hormones what about those are the

posterior pituitary hormones there's

only two you need to know here

there's oxytocin

and anti

diuretic hormone known as adh

also known as vasopressin

all right firstly hypothalamus doesn't

produce

any hormones to travel down to tell them

to be released

it's just a nerve signal in actual fact

the hypothalamus produces these two

hormones

and sends them down and they're simply

stored in the posterior pituitary gland

now what oxytocin does is we know it's

an important hormone for building

relationships

but it also tells smooth muscle to

contract tells the uterus

to contract and tells a smooth muscle in

the breast to contract to eject

milk so uterine contractions

and milk ejection

in addition to building relationships

both positive and negative it's not that

feel-good hormone

that everyone says anti-diuretic hormone

diuresis means to release

urine to release fluid from the body

it's anti-diuresis so it stops

the release of that fluid so it stops

peeing so

this hormone gets released in times of

dehydration if we need to maintain water

we release this hormone this travels to

the kidneys

and the kidneys hold on to water and we

don't pee it out so it stops urination

it's there to maintain hydration

all right so that's the hypothalamus

pituitary glands we've gone through the

adrenal glands we also and we've gone

through the

sex hormones and the thyroid there's a

hormone or

i should say there's a gland that sits

behind the thyroid

called the parathyroid gland

and what the parathyroid gland is it

releases parathyroid

hormone

and it opposes the activity of

calcitonin

so calcitonin decreases calcium

parathyroid hormone increases blood

calcium

so if our calcium too low parathyroid

releases parathyroid hormone

calcium jumps up if calcium is too

high calcitonin's released and it drops

calcium levels

can you see that what's happening here

is the endocrine system maintains

homeostasis maintains function for the

body

brilliant that's the parathyroid hormone

the kidneys also release some hormones

renin for example and erythropoietin

what renin does is it works in

conjunction

to aldosterone increases

blood pressure increases

blood volume erythropoietin increases

red blood cell production why would the

kidneys be in control of red blood cell

production

well because the kidneys need to

maintain itself being fed oxygen because

it's such a hungry tissue

so red blood cell production the

pancreas we can't forget about the

pancreas

the pancreas is both an endocrine tissue

and an exocrine

exocrine means it produces chemicals

that get released into ducts

these ducts are contained and this is

part of the digestive system so it

releases digestive enzymes

but it also releases hormones two really

important hormones

are insulin and glucagon

and again these are opposing hormones so

insulin drops blood glucose levels when

they're high

drops blood glucose glucagon

increases blood glucose levels

after a meal insulin's released pulls

the glucose into the cells to be used

for energy

if we're not eating and it's been four

to six eight hours and we haven't eaten

glucagon's released

and it releases stored glucose into the

bloodstream and then the cells can use

it

for energy and so what we've had a look

at here is a

relatively quick run through an overview

of the endocrine system