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Human Bio Unit 3 - Coggle Diagram
Human Bio Unit 3
Endocrine System:
Endocrine vs Exocrine:
Endocrine:
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- secretes hormones into the surrounding extracellular fluid
- passes into the capillaries by the blood
- E.G. THYROID GLAND, PITUITARY GLAND
Exocrine:
- secretes into a duct that carries the secretion to the body surface or body cavity
- E.G. SWEAT GLANDS, SALIVARY GLANDS
Hormones:
Hormone receptors:
- Hormones only influence a cell with a receptor protein in the membrane
- Receptor proteins are specific
- Limited number of receptor proteins on a cell
- May affect all cells in the body, target cells or target organs
Enzyme Amplification:
- One hormone molecule can trigger the production or activation of thousands of molecules of enzymes
Hormone Clearance:
- Once hormone has produced its desired effect it must be turned off
- Some are broken down in target cell
- Most broken down in the liver and kidneys
- Then excreted either in the bile or urine
Types of Hormones:
Steroid:
- Solubility = lipid-soluble
- Receptor location = diffuses across cell membrane
- Function = activates genes controlling the formation of particular proteins
- Effects = slow response but long lasting
- Example = cortisol, aldosterone, oestrogen, progesterone
Protein/Amine:
- Solubility = water-soluble
- Receptor location = surface of the cell membrane
- Cell membrane interaction = attaches to receptor protein in cell membrane, releases secondary messenger
- Function = a secondary messenger diffuses through cell to activate particular enzymes
- Effect = fast response but short lasting
- Example = protein (insulin/glucagon) or amine (adrenaline/thyroxine)
Hormonal Control:
Hypothalamus:
- Location = base of brain (size of almond)
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- Secretes releasing factors to stimulate anterior pituitary
- Secretes inhibiting factors to slow down secretion of hormones in anterior lobe
- Produces own hormones that are secreted through the posterior lobe
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- secretes releasing factors to stimulate anterior pituitary
- secretes inhibiting factors to slow down hormone secretion in anterior pituitary
- produces own hormones that are secreted through posterior lobe
Pituitary Glands:
- location = below hypothalamus (joined by infundibulum)
- connected by a network of blood vessels
- connected by nerve fibres with nerve cell bodies in the hypothalamus
Thyroid gland:
- located just below the larynx
- produces two hormones in response to TSH
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- thyroxine controls metabolism by:
- regulating chemical reaction in cellular respiration
- regulating synthesis reactions
- Calcitonin regulates calcium in blood by:
- reducing reabsorption in kidneys and breakdown of bone
- high phosphate concentration regulated by:
- reducing reabsorption in kidneys
- moves phosphate into bones
Types of hormones:
Anterior Pituitary:
- FSH (Follicle Stimulating Hormone)
- Targets = Gonads (testes/ovaries)
- Effects = develops eggs, production and maturation of sperm
- Targets = Gonads (testes/ovaries)
- Effects = causes ovulation and forms corpus luteum, stimulates production of sex hormones
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- Effects = stimulates body growth, increases protein synthesis
- TSH (Thyroid stimulating hormone)
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- Effect = stimulates production of hormones from thyroid
- ACTH (Adrenocorticotrophic hormone)
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- Effect = stimulates production of hormones from the cortex of adrenal glands
- PRL (Prolactin releasing hormone)
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- Effect = initiates and maintains milk production
Posterior Pituitary:
- Target = uterus, mammary glands
- Effect = contractions during birth, release of milk
- ADH (Antidiuretic hormone)
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- Effect = remove water from urine, constrict arterioles
Thyroid:
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- Effects = increase metabolic rate (increase O2 consumption and heat production
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- Effect = regulates calcium and phosphate levels in the blood
Parathyroid:
- PTH (Parathyroid hormone)
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- Effect = increase level of calcium in the blood
Thymus:
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- Effect = develops and matures t-lymphocytes
Adrenal glands:
Adrenal medulla:
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- Effect = fight or flight response
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- Effect = same as adrenaline and increase heart rate and force
Adrenal cortex:
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- Effect = reduce sodium and increase potassium in urine
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- Effect = promotes normal metabolism helps withstand stress and repair damage tissues
Pancreas:
- Target = liver, fat storage cells
- Effect = promoting glycogenolysis and gluconeogenesis, increase blood glucose
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- Effect = promoting glycogenesis in liver, skeletal muscles, glucose to fat in adipose tissue, decrease blood glucose
Gonads:
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- Effect = sperm production, development of male sexual characteristics, growth of skeleton and muscles
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- Effect = develops female sexual characteristics, regulates menstrual cycle
- Target = uterus and mammary glands
- Effect = regulates menstrual cycle, prepares mammary glands for milk secretion
Pineal:
- Effect = regulates sleep patterns
Nervous System:
Nerve cells:
- part of the neuron that contains the nucleus and is responsible for controlling the cell
- extensions from the cytoplasm of the cell body that carry messages to the cell body
- single extension from the cell body, can vary from a few mm up to a foot long
- carries information away from the cell body
- divides into small branches, each branch is called an axon terminal
- covers axon of most neurons, axons that are not covered are said to be unmyelinated
- other than the brain and spinal chord the myelin sheath is formed by special cells called Schwann cells which wrap around the axon
- along the axon there are gaps in the myelin sheath, these are called the Nodes of Ranvier
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- speeds up transmission of impulses