Human Biology (Endocrine System)

Question 1

What secretes a hormone?

Answer 1

A gland

Question 2

What do hormones do?

Answer 2

Involved in homeostasis by affecting target organs.

Question 3

What are synthetic hormones developed for?

Answer 3

To control or treat endocrine dysfunction.

Question 4

What are the 2 types of glands?

Answer 4

Exocrine: Secretes into a duct, and secretion is carried to the body surface i.e. sweat glands, mucous glands, salivary glands.

Endocrine: Secrete into extracellular fluid, secretion then passes into capillaries and transported by the blood. e.g. pituitary gland, pineal gland.

Question 5

What do hormones being specific imply?

Answer 5

That they only affect certain cells that are influenced by certain hormones.

Question 6

What is hormone saturation?

Answer 6

When all receptor molecules are occupied, increasing hormones will have no effect.

Question 7

How do hormones change/affect the functioning of cells?

Answer 7

By:

• Changing the type of protein produced
• Changing the activity of proteins produced
• Changing the quantity of proteins produced

Question 8

Are hormones enzymes?

Answer 8

No. They exert influence on enzymes by changing the activities or concentrations.

Question 9

How do hormones affect enzymes?

Answer 9

By:

Changing the shape or structure of an enzyme so it is ‘on’ or ‘off’
Activating certain genes in the nucleus so that an enzyme or particular protein is produced.
Changing the rate of production of an enzyme/protein by changing the rate of transcription or translation.

Question 10

What are the 2 types of hormones?

Answer 10

• Protein/amine
• Steroid

Question 11

How do Protein and amine hormones work?

Answer 11

They are made of short and long polypeptides, water-soluble (cannot diffuse through membrane) and work by attaching to receptor proteins on the membrane of the cell. This protein-receptor complex releases a secondary messenger to diffuse into the cell and activate certain enzymes.

Question 12

What is an example of a protein hormone at work?

Answer 12

Insulin binds to a receptor on the cell membrane and leads to an increase in glucose uptake.

Question 13

How do Steroid hormones work?

Answer 13

Steroid hormones are lipid-soluble, and so work by entering cells and combining with a receptor protein in the nucleus. The hormone/protein complex activates genes controlling the formation of particular proteins.

Question 14

What is an example of a steroid hormone at work?

Answer 14

Cortisol: Promotes normal metabolism, helping the body to withstand stress, repair damaged tissues.

Question 15

What are paracrines?

Answer 15

Secreted by all cells in a particular tissue, used to communicate with neighbouring cells.

Question 16

What is enzyme amplification?

Answer 16

How 1 hormone molecule causes the activation of thousands - a cascade effect, small stimulus - large effect.

Question 17

What is Hormone Clearance?

Answer 17

After the hormone has done its effect, hormones must be turned off. Broken down sometimes in the target cell but mostly in the liver and kidneys. And then secreted into bile or urine.

Question 18

How is hormone production regulated?

Answer 18

Hormones must be regulated to maintain homeostasis and are done so by a negative feedback system. This means responses produced by hormones opposite of the stimulus.

Question 19

What are releasing and inhibiting factors?

Answer 19

Releasing factors: Stimulate the release of a hormone
Inhibiting factors: Slow down the release of a hormone.

Question 20

Hypothalamus (Location and Function)

Answer 20

Located at the base of the brain
Regulates basic functions: Heart rate, Body temperature, water levels.

Question 21

What gland in the brain is responsible for assisting the hypothalamus?

Answer 21

Pituitary gland

Question 22

What is the infundibulum?

Answer 22

Connects the hypothalamus to the pituitary gland
Contains both blood vessels and nerve fibres.

Question 23

How is the pituitary gland structured with the hypothalamus? (Describe with seperation of lobes)

Answer 23

Anterior:
A bed of capillaries that secrete the hormones produced in teh lobe. Small nerve fibres extending from the hypothalamus to release releasing and inhibitng factors.

Posterior:
Long nerve extensions passing through the infundibulum and are stored in the bloodstream.

Question 24

What is the pituitary gland and how does it function?

Answer 24

Known as the Master Gland as it controls the release of hormones from other glands
Vital to the normal functioning of the body
Consists of anterior lobe and posterior lobe

Question 25

How does the anterior lobe function and what hormones does it secrete?

Answer 25

Connected to the hypothalamus by a complex network of blood vessels
Secretions are controlled by releasing and inhibiting factors secreted by the hypothalamus
Hormones secreted by the anterior lobe include gondotropins FSH LH growth hormone TSH, adrenocorticotropic hormone PRL

Question 26

What is the posterior lobe and how does it function?

Answer 26

It does not synthesise its own hormones so it is not a true gland.
It is joined to the hypothalamus by a nerve fibres that come from nerve cells in the hypothalamus and pass through the infundibulum
It releases oxytocin and anti-diuretic hormone made by specialised nerve cells in the hypothalamus move down the long cell extensions ready for release the releases are triggered by nerve impulses from the hypothalamus conducted along the long extensions

Question 27

what is the pineal gland?

Answer 27

It decreases after puberty (in size)
‘
Releases melatonin involved in sleep patterns
Production is stimulated by darkness and inhibited by light

Question 28

What is the thyroid gland? Where is it located? What are the main hormones produced? How is it stimulated?

Answer 28

Locate it just below the Larynx consists of two lobes on either side joined by a narrow piece of tissue
Main hormone is thyroxine made from iodine and an amino acid.
Thyroxine controls body metabolism by regulating reactions
Stimulated in response to thyroid stimulating hormone from the anterior lobe

Question 29

Where’s the parathyroid gland located and what does it secrete?

Answer 29

Usually four in humans embedded in the rear surface of a thyroid gland secretevs parathyroid hormone which controls calcium and phosphate levels in the blood

Question 30

Where is the thymus located and what does it produce?

Answer 30

Located in the chest largest in infants begins to shrink after puberty. Secrets thyrosins influencing the maturation of T-lymphocytes.

Question 31

Where are the adrenal glands located and what are they made of?

Answer 31

Located above each kidney and has an inner adrenal medulla and an adrenal cortex both having different functions

Question 32

What are the hormones produced by the adrenal medulla and what do they do?

Answer 32

Produces adrenaline and noradrenaline
Adrenaline: Help the body prepare for reaction to a threatening situation fight or flight responses
Noradrenaline: Similar effects, in particular increases the rate and force of the heartbeat

Question 33

What are the hormones produced by the adrenal cortex and what do they do?

Answer 33

Releases corticosteroids (>20)
Releases Aldosterone and cortisol
Aldosterone: acts on the kidneys to reduce sodium and increase potassium in urine
Cortisol: Promotes normal metabolism helping the body to withstand stress and repair damaged tissues.

Question 34

What does the pancreas do and what hormones does it secrete?

Answer 34

It is classified as both an exocrine and endocrine gland.
Its secrets digestive enzymes into the small intestine
Endocrine: Islets of Langerhans
Secrets two important hormones involved in blood glucose levels: Insulin and glucagon.
Insulin decreases blood glucose causing cellular uptake
Glucagon increases blood glucose by breaking down glycogen

Question 35

What are androgens?

Answer 35

Male sex hormones these are produced by the testes responsible for the development and maintenance of male characteristics

Question 36

What are oestrogens and progesterone?

Answer 36

Responsible afford the formation of female sex hormones produced by the ovaries and simulate development and maintenance of female sex characteristics.

Question 37

Name and list the other endocrine tissues

Answer 37

Stomach and small intestine both secrete hormones that coordinate exocrine glands of the digestive system
Kidneys secrets hormones including erythropoietin (EPO)
Which simulates the production of red blood cells by bone marrow
The heart secrets a hormone that helps reduce blood pressure
The placenta secrets hormones to help maintain pregnancy and stimulate foetal development and development of mammary glands.