F214 "biology - Communication & Homeostasis And Energy

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Homeostasis

Back 1

The maintenance of the internal environment in a constant state despite external changes.

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Negative feedback

Back 2

Process that brings about a reversal of any change in conditions. Everything is kept constant.

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Positive feedback

Back 3

Process in which any change results in an increase in that change . This destabilises the system. E.g Oxytocin

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Stimulus

Back 4

Any change in the environment that causes a response.

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Response

Back 5

A change in behavior or physiology as a result of change in the environment.

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Ectotherms

Back 6

Organisms that rely on external sources of heat to regulate its body temperature.

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Endotherms

Back 7

Organisms that uses internal sources of heat e.g from metabolism, to maintain it's body temperature.

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Polarised membrane

Back 8

A membrane that has a potential across it.

Front 9

Threshold potential

Back 9

About -50mV. If the depolarisation does not meet this, no action potential is created.

Front 10

Resting potential

Back 10

The potential difference across the cell membrane, when the neurone is at rest.

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Action potential

Back 11

About +40mV. The depolarisation of the cell membrane means the inside is more positive than the outside.

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Generator potential

Back 12

A small depolarisation of the cell caused by Na+ ions entering.

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Depolarisation

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The period when Na+ ions are entering the cell, making the inside less negative than the outside.

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Target tissue

Back 14

A group of cells that possess a specific receptor on their plasma membrane. The shape of the receptor is complementary to the hormone.

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First messenger

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The hormone that transmits a signal around the body.

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Second messenger

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E.g cAMP - which transmits a signal inside the cell.

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Hormone

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A molecule that is released by an endocrine gland, directly into the blood. It acts as a messenger, carrying a signal to a specific target organ or tissue.

Front 18

Adenyl cyclase

Back 18

An enzyme associated with the receptors for many hormones

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Exocrine gland

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A gland that secretes hormones into a duct that carries them where they are used. E.g Salivary gland

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Pancreatic duct

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Tube that collects all the secretions of the exocrine cells in the pancreas and carries all secretions to the small intestine.

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Endocrine gland

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A gland that secretes hormones directly into the blood. Has no duct. E.g. Pituitary gland

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A- cells

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Found in the Islet of Langerhans, secrete glucagon.

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B -cells

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Found in the Islet of Langerhans, secrete insulin.

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Islet of Langerhans

Back 24

Small patches of tissue in the pancreas that have an endocrine function.

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Insulin

Back 25

The hormone that causes blood glucose levels to drop↘⬇↙

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Glucagon

Back 26

The hormone that causes blood glucose levels to rise ↖⬆↗

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Hepatocyte

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Liver cell. They are specialised to perform a range of metabolic functions.

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Hyperglycaemia

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The blood glucose concentration is too high.

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Hypoglycemia

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The blood glucose concentration is too low.

Front 30

Genetically engineered bacteria

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Bacteria that has had a gene coding for human insulin, inserted into it's DNA.

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Transducer

Back 31

Convert one form of energy to another

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Neurotransmitter

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A chemical that diffuses across cleft of synapse to transmit a signal to the post synaptic neurons. E.g. Acetylcholine

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Excretion

Back 33

The removal from the body of these unwanted products of metabolism.

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Deamination

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The removal of the amine group from an amino acid to produce ammonia, and urea is formed.

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Ultrafiltration

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Filtering all small molecules, including urea out of the blood and into the renal capsule (nephron).

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Selective reabsorption

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Taking back useful substances from fluid in the nephron.

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Osmoregulation

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Most water lost in filtration is returned to the blood, controlled by hormone Adh.

Front 38

Respiratory substrate

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An organic substance that can be used for respiration.

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Autotrophs

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Organisms that use light energy or chemical energy and inorganic molecules (co2 + water) to synthesise complex organic molecules.

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Heterotrophs

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Organisms that ingest and digest complex organic molecules, releasing the chemical potential energy stored in them.