S6) Introduction to the Endocrine System & Endocrine Control of the Appetite Flashcards Preview

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Flashcards in S6) Introduction to the Endocrine System & Endocrine Control of the Appetite Deck (50)
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What is homeostasis?

Homeostasis is the maintenance / regulation of a stable condition in an internal environment


Homeostatic mechanisms act to counteract changes in the internal environment. These mechanisms exist on all levels.

Identify some

- Cell e.g. regulation of [Ca2+]i

- Tissue e.g. balance between cell proliferation and cell death

- Organ e.g. kidney regulates water and ion concentrations in blood

- Organism e.g. constant body temperature


What are the different components of a control system?

- Stimulus

- Receptor

- Control centre

- Effector


Illustrate how the different components of a control system act to ensure homeostasis


What is a biological rhythm?

biological rhythm is any cyclic change in the level of a bodily chemical or function


What is a circadian rhythm and how is it controlled?

- A circadian rhythm is a biological rhythm which follows a 24 hour cycle

- It is regulated by a small group of neurones in suprachiasmatic nucleus (biological clock) and varies according to the environment (light, temperature, social interaction, exercise, eating/drinking pattern)


How does jet lag arise?

Jet lag occurs due to long haul flights crossing time zones resulting in mismatch between environmental cues and the biological clock 


Which hormone is involved in setting the biological clock?

Melatonin, from pineal gland


Compare and contrast negative and positive feedback, providing an example for each

Negative feedback: a response which reverses the direction of change e.g. baroreceptors in blood pressure control

Positive feedback: a response which reinforces the direction of change e.g. hormones in ovulation


Body water homeostasis is an example of a feedback system.

In light of this, describe the body water distribution in a 70 kg adult male


Distinguish between osmolarity and osmolality

Osmolarity is the number of osmoles per litre of solution

- Osmolality is the number os osmoles per kilogram of solution


What monitors the osmotic pressure of blood plasma?

Osmotic pressure of blood plasma monitored by osmoreceptors in hypothalamus 


Serum osmolality useful when investigating hyponatraemia.

What is the normal range for this?

275 - 295 mOsmol/kg 


Illustrate the control system set up as ADH regulates serum osmolality in body fluid homeostasis 


Illustrate the control system set up by the homeostatic regulation of plasma glucose levels by insulin and glucagon


What is the endocrine system?

The endocrine system is a collection of glands located throughout the body


What are hormones and what do they do?

Hormones are chemical signals produced in endocrine glands/tissues that travel in the bloodstream to cause an effect on other tissues 


Identify the ten major endocrine glands in the human body


There are four different mechanisms of communication via hormones.

Identify and describe them


The endocrine and nervous systems have several features in common.

Describe five of these similarities

- Both neurons and endocrine cells are capable of secreting

- Both neurons and endocrine cells can be depolarised

- Some molecules acts as both neurotransmitter and hormone

- The mechanism of action requires interaction with specific receptors in the target cells

- Both systems work in parallel to control homeostasis


Compare and contrast the endocrine and nervous systems in terms of the following:

- Signal

- Nature

- Conveyance

- Mediators

- Speed


Identify the four different types of hormones and describe their relative solubility

- Peptide / polypeptide – water soluble 

- Amino acid derivatives (amines) – catecholamines are water soluble, thyroid hormones are lipid soluble

- Glycoproteins – water soluble 

- Steroids – lipid soluble 


Provide three examples of peptide hormones

- Insulin

- Glucagon

- Growth hormone


Provide three examples of glycoprotein hormones

- Luteinizing hormone

- Follicle stimulating hormone

- Thyroid stimulating hormone 


Provide three examples of amine hormones

- Noradrenaline (& adrenaline)

- Melatonin

- Thyroid hormone


Provide three examples of steroid hormones

- Cortisol

- Aldosterone

- Testosterone 


How are hormones transported?

- Some hormones travel in blood in simple solution e.g. peptides, NA

- Most hormones must bind to specific proteins 


In terms of hormone transport, describe three roles of transport proteins

- Increase solubility of hormone in plasma

- Increase half-life

- Readily accessible reserve 


3 factors determine hormone levels in the body.

Identify and describe them

Rate of production – synthesis and secretion

- Rate of delivery – dependent on rate blood flow to a particular organ 

- Rate of degradation – hormones are metabolised and excreted from the body


How do hormones exert their effects?

Hormones exert their effects by binding to specific receptors