Lecture One: Body Fluid Comparments Flashcards

0
Q

What is protoplasm?

A

different substances that make up the cell

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1
Q

What do homeostatic responses of the body ensure?

A
  • The internal fluid volume an composition remain fairly constant
  • The preservation of the internal environment
  • that cells are protected from insults that could compromise their survival
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2
Q

What are cells?

A

The basic unit of living organisms

Simplest structural units which complex multi cellular organisms can be divided into and still retain the functions characteristic of life

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3
Q

What is differentiation?

A

The process of transforming an unspecialised cell into a specialised cell

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4
Q

What happens during cell development?

A

Cells become specialised for the performance of a particular function

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5
Q

What can each cell perform?

A

Fundamental cellular processes

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6
Q

List some fundamental cellular processes

A
  • movement across membranes
  • energy production
  • protein synthesis
  • maintenance of cell volume etc
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7
Q

What are fundamental cellular processes essential for?

A

Maintaining the cell’s individual integrity and life

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8
Q

What does each cell simultaneously perform that, in concert with actions of other cells contributes to survival of the organism?

A

One or more specialised activities

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9
Q

How are cells classified? Give examples

A

Classified by the broad types of function they perform:

  • muscle cells
  • nerve cells
  • epithelial cells
  • connective tissue cells
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10
Q

What to specialised cells associate with other cells to form?

A

Tissues

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11
Q

What are organs composed of?

A

The 4 kinds of tissues arranged in various proportions and patterns

  • sheets
  • tubes
  • layers
  • bundles etc
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12
Q

What is an organ system?

A

Collections of organs that together perform an overall function

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13
Q

Homeostasis is mostly achieved by

A

Negative feed back mechanism which requires at least four elements

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14
Q

What is the homeostatic control mechanisms

A
  • Where The activities of cells, tissues and organ systems
  • are regulated and integrated with each other in such a way that
  • any change in the extracellular fluid initiates a series of reactions that strive to
  • minimise the change
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15
Q

Disruptions to homeostasis can arise from which two stimuli?

A
  1. Internal

2. External

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16
Q

Give an example of internal stimuli that disrupts homeostasis

A

Change in blood glucose levels

Change in pH

17
Q

Give examples of external stimuli that disrupts homeostasis

A

Exercise

Physical insults like heat, lack of oxygen,

Psychological stresses like work stress, death in family

18
Q

How does homeostasis occur at the level of single cells?

A

By the regulation of

  • volume
  • Concentration of electrolytes
19
Q

What proportion of body weight does water account for?

A

60% for men, 50% for women

20
Q

What main compartments is total body water distributed across?

A

Intracellular fluid 60%

and extracellular fluid 40%

21
Q

What are the components of extracellular fluid?

A
Interstitial fluid (75%)
Plasma volume (20%)
Transcellular fluid (5%)
Blood volume (PV/(1-hematocrit))
22
Q

What are the components of a feed back system?

A
  1. Sensor:
    System senses vital parameter e.g. Glucose
  2. Ability to compare to reference:
    Compares input signal with an internal reference and forms different signal
  3. Sufficient gain:
    System multiplies error signal by proportionality factor to produce some form of output signal e.g. Release of insulin
  4. Effector mechanism:
    Activated by output signal. This makes the responses.
    This opposes the source of input and brings vital parameter closer to set point

(In the case of a negative feed back mechanism)

23
Q

What are the fundamental importances of having an asymmetrical distribution of ions?

A

Ion gradients are responsible for

Setting the membrane potential
Generating electrical activity in nerve and muscle
Initiation of muscle contraction
Providing energy for uptake of nutrients and expulsion of waste products
Generation of intracellular signalling cascades

24
Q

How are transmembrane ion gradients maintained?

A

By transporting ions into and out of cells against their concentration gradients in a process that utilises energy

25
Q

How much of resting energy consumption goes into maintaining ion gradients..

A

30%

26
Q

How is energy released from ion gradients?

A

By the diffusion of an ion down it concentration gradient

27
Q

What are the determinants of cell volume?

A

The total number of osmotically active particles within a cell
The effective osmolarity of the ECF

28
Q

How is osmolality expressed ?

A

By the concentration of solutions in terms of number of particles free in water

29
Q

What does cell volume reflect?

A

Water content

30
Q

What happens to body water due to the cell membrane’s natural permeability to water?

A

Water will be distributed between cells And the interstitial fluid to maintain a Constant activity of water in each compartment

31
Q

What occurs as a result of plasma membranes being naturally impermeable to most salutes in the interstitial space which surrounds cells?

A

The osmolality of the interstitial fluid determines cell volume

32
Q

What happens when the osmotic pressure of the interstitial fluid increases?.

A

Water will move out of cells causing them the shrink

33
Q

What happens if the osmotic pressure of the interstitial fluid decrease?

A

Water will move into cells causing them to swell?

34
Q

What is the relationship between interstitial fluid and cell size?

A

Interstitial fluid is inversely proportional to cell size

35
Q

Describe the relationship Between red blood cells suspended in normal saline (0.9g NaCl per 100mL) which is 0.15M which therefore has an osmolality of 300mOsm

A

The external solute concentration is isotonic to RBCs

36
Q

What happens If external solute concentration is greater than concentration within RBCs?

A

This external solution is hypertonic. This will cause RBCs to shrink

37
Q

What happens if the external solute concentration is less than that of the concentration within RBCs?

A

The external solute concentration will be hypotonic, this will cause RBCs to swell. If the swelling is too large this may lyse, causing rupture of the plasma membrane

38
Q

Describe the relationship of red blood cells suspended in 0.28M solution of urea

A

Urea is isoosmotic as it has the same osmolarity as the RBC.

However the Urea solution is hypotonic in comparison to the RBCs
Cells are permeable to urea so urea will go into the cell due to concentration gradient . Water will follow and this will cause the cell to lyse.

39
Q

What is regulation of osmolarity of ECF essential for?

A

The maintenance of normal cell function