Hypothalamus and Pituitary gland

What do the hypothalamus and pituitary gland do?

they work together to control many of the other endocrine glands and ensure hormone homeostasis

what are the hypothalamus and the pituitary called?

command centre of the body.

What is systemic circulation?

blood stream supplying the body

Where is the hypothalamus located?

located in the brain, below the thalamus and above the pituitary.

In what system does the hypothalamus have roles in?

it serves as a connection between the nervous and endocrine systems.

What basic functions of the body does the hypothalamus regulate?

-body temperature

-water balance

-heart rate

-secretion of releasing factors and inhibiting factors that stimulate the anterior pituitary to produce other hormones/ inhibit.

-production of hormones that travel along the nerve fibres into the posterior pituitary.

How is the hypothalamus and the pituitary gland connected?

they are joined by a stalk called the infundibulum.

What is the infundibulum?

a stalk that attaches the hypothalamus and the pituitary gland. it contains blood vessels and nerves that communicate with the pituitary.

Where does the pituitary gland sit?

just under the hypothalamus in a pocket of bone

What are the two lobes of the pituitary gland?

anterior and posterior lobes

Which is closest to the front of the body, anterior or posterior lobes?

the anterior lobe

What is the structure of the anterior lobe?

it is made up of secretory cells.

there are no nerves connecting to the hypothalamus , rather it is connected by a complex network of blood vessels lying in the infundibulum

What is the structure of the posterior lobe?

it is joined to the hypothalamus by nerve fibres that come from nerve cell bodies in the hypothalamus and pass the the infundibulum.

Which of the lobes secrete hormones?

the anterior lobe. This lobe receives releasing factors from the hypothalamus via blood vessels in the infundibulum. this then stimulates the production if hormones in response to stimulus by hypothalamus and releases them into systemic circulation.

the posterior lobe is not a true endocrine gland, it does not produce and secrete hormones only stores and release them.

What is the communication pathway between the hypothalamus and the anterior pituitary lobe?

1. the hypothalamus produces releasing factors

2. these are secreted into the blood vessels of the infundibulum

3. releasing factors travel through these blood vessels to the anterior pituitary

4. the releasing factors stimulate the anterior pituitary to produce and release other hormones

5. the hormone produced is released into the systemic circulation

what does the hypothalamus release to produce the growth hormone?

it releases the growth hormone releasing factor (GHRF) and the anterior pituitary will then produce and secrete the growth hormone (GR)

What hormones are released by the anterior pituitary?

-Gonadotropins, e.g (FSH and LH)

-Growth hormone (GH)

-Thyroid stimulating hormone (TSH)

-Adrenocorticotropic hormone (ACTH)

-Prolactin (PRL)

What is the function of follicle stimulating hormone (FSH)?

it stimulates the development of the follicles that contain eggs in the ovary of the female. in the male, FSH stimulates the production and maturation of sperm in the testes

What is the function of Luteinising Hormone (LH)?

Females: it works with LH to bring about ovulation and to form a structure called the corpus luteum after ovulation.

Males: stimulates the interstitial cells in the testes to secrete male sex hormones.

What is the function of adrenocorticotropic hormone (ACTH)?

adrenocorticotropin controls production and release of some of the hormones from the cortex of the adrenal glands.

What is the function of prolactin (PRL)?

or lactogenic hormone, works with the other hormones to initiate and maintain milk production in females.

What is the communication pathway between the hypothalamus and the posterior pituitary?

1. the hypothalamus manufactures the hormones oxytocin and ADH: Anti-diuretic hormone.

2. These travel down the nerve fibres within the infundibulum to the posterior pituitary.

3. the hormones are then released into the systemic circulation by the posterior pituitary in response to nerve impulses.

When a hormone is stored in the posterior pituitary, when does it know to release the hormone into the systemic circulation?

It is a response to nerve impulses from the hypothalamus which detects that oxytocin levels of ADH levels need to increase.

What hormones do posterior pituitary release?

oxytocin and anti- diuretic hormone

What is the function of oxytocin?

it stimulates uterine contractions, with a increasing amount being released during labour. It also stimulates contraction of cells in the mammy glands (resulting in milk production)

What is the function of antidiuretic hormone (ADH)?

also known as vasopressin, it causes the kidneys to remove water from the urine that is forming (ADH helps retain fluid within the body). At high quantities it can cause cinstriction of small arteries.

What type of hormone is the growth hormone (GH)?

peptide

Where is the growth hormone produced?

in the anterior pituitary in response to the growth hormone releasing factor from the hypothalamus.

is the growth hormone an anabolic or catabolic hormone?

anabolic hormone as it boils up tissues.

What is the effect/ function of the growth hormone?

-increases height (bone and muscle growth) in children and adolescents

-increases protein synthesis

-increases metabolism of fats

- increases muscle mass

-increases bone mineralisation and density

-increases growth of internal organs (not the brain)

-Acts on the liver to increase blood glucose (increasing gluconeogenesis)

How does negative feedback look like for the growth hormone?

-the negative feedback effects of GH on body stimulates release of GHIF (growth hormone inhibiting factor) from hypothalamus which inhibits the release of GH from the anterior pituitary

What is it called when there is too much growth hormone?

Growth hormone hyper secretion

What is it caed when there is not enough growth hormone?

Growth hormone hyposceretion (/ deficiency)

What is the pathway of Anti-diuretic hormone?

the water concentration of the blood decreases (as the salt concentration increases). this is detected by the osmoreceptors in the hypothalamus. the ADH travels down nerves to the posterior pituitary. then ADH is released. This affects the body by increasing the permeability of the distal convoluted tubules and collecting duct. this increases the water reabsorption into the blood. and then water reabsorption is restored. Negative feedback is increasing water concentration of blood (decreasing salt concentration) it will inhibit further ADH release