Physiology 4: Introduction to endocrine physiology Flashcards

Question 1

Q

What are the primary endocrine glands, and why are they called that?

Answer

A

Glands dedicated to endocrine function – Called primary endocrine organs because producing hormones is their primary function

Hypothalamus – In brain, one of the major control centres for endocrine system. Regulates hypothalamus pituitary axis, in CNS, can react to many different stimuli
Pituitary gland
Thyroid gland – in front of neck. Only endocrine gland that can be palpated (felt). Can detect changes by feeling
Parathyroid glands (behind the thyroid gland)
Adrenal glands (on top of kidneys) - produces adrenalin, steroid hormones
Pancreas – sits under stomach near small intestine. Regulates glucose
Ovaries + testes – regulate reproductive function

Question 2

Q

What are the secondary endocrine organs?

Answer

A

Organs with a primary function other than endocrine

Heart - primary function: pumping blood. Also produces hormones
Stomach - can produce hormones that regulate appetite and the absorption of nutrients in the stomach
Liver - primary function: cleaning out waste products from blood. Can also produce hormones.
Kidney - primary: excretion. Can produce hormones that regulate plasma volume
Small intestine
Skin - vitamin D for regulating strength of bones, regulating calcium
Placenta (pregnant female) - produces hormones during pregnancy

Question 3

Q

What is the function of the endocrine system?

Answer

A

Integration and control

Coordinating the function of cells and tissues all over the body (e.g. metabolism)
Control of the internal environment (homeostasis) and the response to the external environment (The only other system that also does this is the nervous system)
Endocrine system control tends to be slower and acts over a longer period compared with the nervous system - because it relies on the transport of hormones.

Question 4

Q

What are the key features of endocrine glands?

Question 5

Q

What is a hormone?

Question 6

Q

What are the chemical classifications of hormones?

Answer

A

Amines – derived from the amino acid tyrosine e.g. adrenaline

Peptides/proteins – synthesised by translation of mRNA on ribosomes – e.g. insulin

Steroids – synthesised from cholesterol - e.g. testosterone

Question 7

Q

What is the difference between Hydrophillic and Hydrophobic hormones?

Answer

A

Hydrophilic - Soluble in water (‘water loving) but unable to cross cell membrane unaided - These are the catecholamines, amines (except for thyroid hormones) and peptides/proteins . Hydrophilic hormones are able to be dissolved in the plasma of the blood. Transported in the dissolved form.

Hydrophobic – Not easily soluble in water (‘water-fearing’) but they are soluble in lipids, so are able to cross the cell membranes - These are the steroid hormones and thyroid hormones - Hydrophobic hormones bind to a specific carrier protein (or non-specific proteins like albumin) for transport in the blood.

Question 8

Q

There are three main methods of cell communication. What are they?

Question 9

Q

What triggers the release of hormones?

Answer

A

Hormonal stimuli: in response to another hormone (e.g. hypothalamus stimulates production of hormone in the pituitary

Humoral stimuli: in response to a change in the internal environment of the body (e.g. a change in blood glucose levels, Na/K levels, osmolarity - try and maintain homeostasis

Neuronal stimuli: as a response to emotional or physical stress; other cognitive associations (within our minds) - e.g. visual stimuli, heat, stress

Question 10

Q

How fast is release of hormones?

Answer

A

Steroid hormones (hydrophobic)

Synthesised on demand (synthesised from cholesterol)
Unable to be stored
Release is slow in response to trigger, as the hormone has to be made first - Released by diffusion
Metabolised slowly, so actions lasts hours to days
Generally act by regulating gene expression - longer lasting effect

Peptide hormones (hydrophilic) - e.g. adrenaline