Endocrine System Flashcards

1
Q

Describe homeostasis

A

Self regulating processes to enable the body to maintain its normal function and environment
Requires constant monitoring and changes from two body systems:
Autonomic nervous system- make rapid changes
Endocrine system- makes slower and more precise changes

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2
Q

What is the endocrine system

A

Collection of glands that secrete into the bloodstream
Surrounded by capillaries which carry the secreted hormone into the bloodstream

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3
Q

What are hormones

A

Are chemical substances released by the endocrine system
They act as messengers to instruct cells on how to function
Hormones enable organs to communicate with tissues
They are secreted into the bloodstream, although they may come into contact with many different cells, they only act upon cells that have a receptor to that specific hormone
Hormones stimulate cell growth, protein production and metabolism

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4
Q

What is exocrine

A

Exocrine glands secrete into ducts

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5
Q

Describe endocrine hormones

A

Released into bloodstream and carry message far away from the gland they are released from
Paracrine hormones - carry message close by to neighbouring cells
Autocrine hormones - act on the cell that they are released from

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6
Q

Describe type of hormones and receptor sites

A

Some hormones are water-soluble: peptide and amine hormones
Water soluble hormones work on receptors on the surface of the cell e.g. glucagon and insulin

Some hormones are lipid- soluble: steroid hormones
Lipid soluble hormones work on receptors inside the cell within their nuclei e.g. progesterone and testosterone

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7
Q

Describe the transport of hormones

A

Some ( a minority) hormones travel freely in the blood
Most hormones require a transport protein to bind to
Transport proteins hold the hormone inactive during transport, most are produced by the liver and are specific to the hormone
E.g. corticosteroid binding globulin which binds cortisol

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8
Q

Describe feedback loops

A

The product feeds back to regulate its own release
Most hormones work on a negative feedback loop e.g. high concentrations of them will result in less being released
This keeps hormone levels within a tightly controlled range

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9
Q

Give an example of negative feedback loop

A

Insulin and glucagon
Blood sugar high - insulin release increased- blood sugar lowered - insulin release reduced
Blood sugar low - glucagon release increased- blood sugar increased- glucagon release reduced

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10
Q

Describe positive feedback loop with an example

A

The release of a product results in more release of the product
Oxytocin released during labour - uterus contracts - fetus propelled through birth canal and presses on cervix - more oxytocin is released from posterior pituitary gland - more contractions - fetus presses more on cervix- more oxytocin is released from the posterior pituitary gland- more contractions - baby is born

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11
Q

Describe the hypothalamus

A

Classified as a part of the brain rather than an endocrine gland
It secretes hormones that control the pituitary gland and indirectly influences many others

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12
Q

Describe the hypothalamus and pituitary unit

A

The hypothalamus sends messages to the anterior pituitary gland via capillaries known as the pituitary portal system
Hypothalamic hormones travel through these capillaries and pass messages to the anterior pituitary gland
The hypothalamus sends messages to the posterior pituitary gland via nerve impulses

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13
Q

Describe the anterior pituitary gland

A

Hypothalamus and anterior pituitary use negative feedback loops for regulation
Examples of hormones released by ant pit gland:
Growth hormone- stimulates growth and division of bone and skeletal muscle; anabolic effects, secretion highest in childhood and adolescence
Hypothalamus releases:
GHRH growth hormone releasing hormone to stimulate GH release
GHRIH growth hormone release inhibiting hormone to inhibit GH release

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14
Q

Describe posterior pituitary gland

A

Is formed of nervous tissue, hence messages sent from hypothalamus via nerve impulses
Examples of hormones released:
Oxytocin - positive feedback loop for labour and breastfeeding
ADH anti diuretic hormone- negative feedback loop for fluid balance, increases water reabsorption when osmotic pressure is high - high osmotic pressure = concentrated blood/ not watery

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