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Flashcards in Homeostasis Deck (43)
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Describe the reasons for a Fever/Pyrexia

This occurs due to a release of endogenous pyrogens (EPs = cytokines) that are released into the circulation --> causing thermoregulatory responses

This releases heat production, whilst reducing heat loss --> causing the core temperature to rise

This higher body temperature then stabilises


What causes Rheumatoid Arthritis?

A swollen/inflammed synovial membrane


What effect does an increase in wind have?

Increases heat output


Define what is meant by the 'Musculoskeletal System'

The skeleton, muscles and accessory tissues which together allow locomotion and articulation


Describe the regulation of 1,25(OH)2 D3 production

The skin converts Vitamin D3 into 25(OH)D3, which is then converted to 1,25(OH)2 D3 due to the secretion of PTH

The formation of this molecule causes an increase in Ca2+ and a reduction in PO4^3- --> which inhibits PTH secretion and the conversion of the first step

The amount of inactivation (first molecule to 24,25(OH)2 D3) also effects the amount of 1,25(OH)2 D3 that is in the body


What is the recommended physical activity level per week?

150mins of moderate activity


Explain how Endochondral Ossification occur?

Hylaine cartilage is formed, creating a matrix for real bone to replace later on

Once the bone is formed there is some cartliage left in the Epiphyseal Plate --> which is used for further growth in the future


Define Healthy Nutrition and Malnutrition

Healthy Nutrition - A balanced diet that contains adequate amounts of nutrients in relation to bodily requirements


Malnutrition - Any physical condition resulting either from an inappropriate or inadequate diet that either provides too much or too little of a necessary nutrient


What are the two types of vitamins in the body?

Water soluble = not stored

Fat soluble = stored


Describe the main points of a synovial joint

Hylaine Cartilage covers the end of the bones

A fibrous layer that attatches to the periosteum

An inner synovial membrane that produces synovial fluid



What are the 4 types of bone?






Explain how intramembranous Ossification

The bone is formed directly from inside of the condensation

No cartilage is used


What is Calcitonin?

A single chain polypeptide

It is secreted more when there is high [Ca2+]

Its effect is to reduce body Ca2+ levels --> so it has the opposite effects to PTH


Describe 1,25 (OH)2 D3

It is an active metabolite of Vitmain D3

Its a secosteroid (due to its open B ring)


Its a very lipohillic molecule so it needs to be carried by transcalciferin (a vitamin D binding protein) --> only the unbound molecule is active


The molecule acts on osteocytes/blasts, as well as nuclear receptors


What are the three different types of cartilage?

Hylaine - Found in growth plates, joint surfaces and the temporary bone scaffold


Fibrocartilage - Found in the menisci and intervertabral discs --> There is NO fibrous perichondrium


Elastic - Present in the inner ear, epiglottis and larnyx


What is the difference between Hypercalcemia and Hypocalcemia?

Hypercalcemia - When there is too much PTH --> so too much Ca2+ is formed


Hypocalcemia - When there is PTH resistance, or a lack of Vitmain D intake


Is body temperature normally warmer or cooler than the outside temperature?



Long bones are made up of many units that work together, so they are refered to as....

A modular tissue


List why fats are important in the diet

They are a good source of essential fatty acids (alpha linoleic acid and linoleic acid)

They acts as carriers for fat soluble vitamins

They are used for membrane synthesis, as well as glycolipids and steroid hormones


Explain how post-natal bone growth occurs

Chondroblasts in the Epiphyseal Plate quickly divide, lengthening the bone

Old chondrocytes then enlarge, triggering the calcification of the matrix

The matrix becomes calcified, whilst the chondrocytes die

Osteoclasts then digest the cartilage, whilst osteoblasts replace it with actual bone


How does the body cope when above/over 37 degrees

Above - Sweating, vasodialation and shievering in order to get blood into the periphery


Below - Vasoconstriction and horripilation


Define BMR - TEE - PAL - EAR

Basal Metabolic Rate - The mimimum amount of energy required to maintain vital functions

Total Energy Expenditure - The combination of BMR + energy needed to process food + physical activity

Physical Activity Level - A 24hr index of energy expenditure due to physical activity

Estimated Average Requirement - BMR x PAL


Explain the differences between an Osteoblast - Osteocyte - Osteoclast

Osteoblast - A cell that forms the bone matrix by several working together


Osteocyte - A cell that maintains the bone tissue, and is formed by several osteoblasts becoming imbedded into the membrane


Osteoclast - A multinucleated cell that breaks down and absorbs old bone during growth


How much calcium is the ultrafiltrate is reabsorbed?

Almost all of it


"Humans are homeothermic" means what?

They are warm-blooded


Where is the biggest store of calcium in the body?

The bone


What is PTH?

What does it do?

Where is it produced/released?

Parathyroid Hormone


It is a single chain polypeptide that srimulates both osteoblasts and osteocytes (and osteoclasts indirectly) --> its also got a short half-life, so its effects are only for a small period of time

- The purpose of this is to increase plasma Ca2+ levels


Its produced in the chief cells of the parathyroid gland

The less ionized calcium that is present --> the more PTH is secreted




Explain the importance of the hypothalamus in terms of thermoregulation

The hypothalamus takes in all the information from thermoreceptors in the periphery and the core and compares it to the set point of 37oC

Above 37 - Detected in the anterior hypothalamus

Below 37 - Detected in the posteriour hypothalamus


Why are many dietary carbohydrates a good source of fibre?

And why are they useful?

Many polysaccharides are plant based, and so they can't be broken down

These can then add bulk to the GI tract

They're also useful for the production of short chain fatty acids


What is the RNI for protein per day?