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WACE Human Biology > Endocrine System > Flashcards

Endocrine System Flashcards

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1
Q

What is Homeostasis?

A

The maintenance of a constant internal environment, it is important that the cells environment is at an optimal level for normal cell and body function

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2
Q

What is a feedback loop?

A

A circulation station in which the body responds to a change or stimulus with the repose alternating the original stimulus. There are two responses; negative and positive feedback

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3
Q

What is Negative feedback?

A

The response causes the stimulus or variable to change in a direction opposite to that of the original state

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4
Q

What is Positive feedback?

A

An increase or reinforcement of a stimulus e.g. prolactin in milk production, or labor

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5
Q

What is the role of the Endocrine System?

A

Secretes chemical messengers or hormones into the blood, hormones are normally slower than nerve impulses

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6
Q

What are the two types of Endocrine Glands?

A
  1. Exocrine - secretes into a duct, carries the secretion to the body surface or body cavity e.g. sweat, mucous, alimentary canal, salivary glands
  2. Endocrine - secrete hormones unto extra cellar fluid (ductless), carried into the capillaries and into the blood e.g. thalamus, hypothalamus, pineal gland and pancreas
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7
Q

What are some of the Endocrine Glands in the body?

A
  • Hypothalamus
  • Thalamus
  • Pineal gland
  • Thymus
  • Thyroid gland
  • Parathyroid gland
  • Pancreas
  • Gonads (ovaries & testes)
  • Pituitary gland
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8
Q

What is a Hormone?

A
  • The secretion of an endocrine gland is called a hormone
  • May be proteins, steroids, or amines
  • Hormones are transported through the body via the blood
  • A hormone may affect all cells of the body or only particular groups of cells, target cells or particular organs or target organs
  • Hormones are only able to influence cells that have the correct receptor for the hormone
  • Cells may communicate with other cells in the same tissue by secreting chemicals that diffuse to adjacent cells, these are called paracrine’s or sometimes local hormone
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9
Q

What are Paracrines?

A
  • Local hormones

- Paracrine’s are secreted by all cells in a particular tissue and move through extra cellar fluid

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10
Q

Hormones May?

A
  • Activate certain genes in the nucleus so that particular enzyme or structural proteins are produced
  • Change the shape or structure of an enzyme so that it is turned ‘on’ or ‘off’
  • Change the rate of production of an enzyme or structural protein by changing the relate of transcription and translation during protein production
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11
Q

What are the two types of Hormones?

A

~Protein or Amine Hormones and Steroid Hormones

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12
Q

What are Protein or Amine Hormones?

A
  • Protein or Amine Hormones are water Soluble and cannot cross cell Membrane
  • They work by attaching to receptor proteins in the membrane of the target cell
  • The combination of the hormone with receptor causes a secondary messenger substance to diffuse through the cell and activate particular enzymes
  • Receptor proteins are specific, each type of receptor will bind only with one specific molecule (lock and key analogy)
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13
Q

What are Steroid Hormones?

A
  • Steroid Hormones are lipid soluble and can cross Cell Membrane
  • They work by entering the target cells and combining with a receptor protein inside the cell
  • The receptor may be on the mitochondria or on other organelles
  • The hormone-receptor complex activates the gene controlling the formation of particular proteins
  • Hormones change the functioning of cells by changing the type, activities or quantities of proteins being produced
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14
Q

What does Enzyme Amplification refer to?

A
  • 1 hormone molecule ——> activates thousands of enzymes called enzyme amplification
  • A very small stimulus can produce a large effect, hormones trigger a cascade of events
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15
Q

What is Hormone Clearance?

A
  • Once a hormone has completed its job it is turned off
  • Hormone molecules are broken down in a target cell or liver & kidneys
  • Degraded hormones are excreted in bile or urine
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16
Q

What is the Hypothalamus?

A
  • Located at the base of the brain
  • Regulates many body functions such as temperature, water balance and heart rate
  • Many functions of the hypothalamus are carried out in Pituitary Gland
  • The hypothalamus produces many different hormones, some of them are carried out in the blood to the anterior lobe of the pituitary, where they stimulate or inhibit the release of hormones made in the anterior, other hormones pass along nerve fibres from the hypothalamus to the posterior lobe of pituitary where the are then secreted
17
Q

What is the Pituitary Gland?

A
  • Located just under the hypothalamus and is joined to the Hypothalamus by a stalk called the Infundibulum
  • It is absolutely vital to normal functioning of the body
  • Pituitary is often called ‘master gland’ because it regulates the activity of other glands
  • Contain two lobes; anterior and posterior, each which function separately
18
Q

What is the Anterior Lobe?

A
  • The Anterior lobe of the pituitary releases a number of hormones that regulate a great range of bodily activities
  • Located at the front of the Pituitary Gland and contains no nerves connecting to the hypothalamus but it is connected by a network of blood vessels
  • Secretions of the Anterior lobe are controlled by releasing and inhibiting factors secreted by the Hypothalamus
  • They are secreted in the extracellular fluid around the cells of the hypothalamus and are carried by the blood to the anterior lobe of the pituitary
  • Hormones released by the Anterior lobe of the Pituitary are; Follicle Stimulating Hormone (FSH), Luteinising Hormone (LH), Growth Hormone (GH), Thyroid Stimulating Hormone (TSH), Adrenocorticotropic Hormone (ACTH) and Prolactin (PRL)
19
Q

What is the Posterior Lobe?

A
  • The Posterior (rear) lobe is not a true gland because it does not secrete substances
  • It is joined to the Hypothalamus by nerve fibres that come from nerve cell bodies in the hypothalamus and pass through the infundibulum to posterior lobe
  • The Posterior lobe of the Pituitary releases the hormones Oxytocin and Antidiuretic Hormone but neither is manufactured in the Posterior lobe, both are produced in special nerve cells in Hypothalamus of the brain
  • The Nerve cells have long extensions that pass through the Infundibulum to the posterior lobe
  • Hormones manufactured in the cells move down the extensions and are stored ready for release into the bloodstream
  • The release of the hormones if triggered by nerve impulses initiated in the Hypothalamus and conducted along the cells extensions
20
Q

What is the role of the Thyroid Gland?

A
  • Located in the neck below Larynx
  • Contains two lobes (one of either side connected by tissue)
  • Secretes Thyroxine, in response to TSH
  • Controls body metabolism and body temperature
    e. g. Hypothalamus —> Anterior pituitary —> TSH —> Thyroid —> Thyroxine
21
Q

What is the role of the Parathyroid Glands?

A
  • Located at the back of thyroid lobes, contains 4 glands
  • Secretes Parathyroid Hormone (PTW)
  • Controls calcium and phosphate levels in the blood
22
Q

What are the Adrenal Glands?

A
  • Two glands, one above each kidney
  • Adrenal Medulla (Inner) - release adrenaline and noradrenaline (In response to the fight to flight system stimulated by Sympathetic Nervous System)
  • Adrenal Cortex (Outer) - release Adolesterone which reduces the amount of sodium and increases potassium in urine, and cortisol which promotes normal metabolism and helps the body deal with stress
23
Q

What is the role of the Pancreas?

A
  • Both an Endocrine and Exocrine gland
  • It is a endocrine when it secretes insulin and glucagon
  • It is an exocrine when it secretes digestive enzymes (pancreatic amylase, lipase and protease) into the small intestine through pancreatic duct
24
Q

What are other Endocrine Glands?

A
  • Stomach & Small Intestine - Secrete hormone that regulate exocrine glands for digestive system
  • Kidneys - Secretes erythropoietin (EPO), stimulates production of red blood cells by bone marrow
  • Heart - Secretes a hormone that reduces blood pressure
  • Placenta - Helps maintain pregnancy, stimulates development of foetus, stimulates mammary glands

WACE Human Biology (15 decks)

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