Blood physiology - Body fluids Flashcards
Explain the relationship between fat content and body water as a % of body weight
Relationship is inversely proportional.
As the percentage of body fat increases, the percentage of body water decreases, and vice versa. This relationship is primarily due to differences in the composition of fat tissue and lean tissue. Fat has less water than lean tissue.
What is intracellular fluid?
This is the fluid contained within the cells of the body
Approximately two-thirds of the total body water is found within cells.
Function: Intracellular fluid serves as a medium for cellular metabolism, transport of nutrients and waste products, and maintenance of cell structure and integrity.
What is extracellular fluid?
Extracellular fluid is found outside the cells and includes fluid in interstitial space and plasma.
Extracellular fluid facilitates the exchange of substances between cells and the bloodstream, helps maintain fluid balance and electrolyte concentrations, and supports various physiological processes
What is trans-cellular fluid?
Trans-cellular fluid consists of small, specialised compartments separate from the main extracellular and intracellular compartments e.g cerebrospinal fluid, pleural fluid.
Serves specific functions depending on its location, such as providing cushioning and lubrication, supporting organ function, and maintaining homeostasis in specialised environments.
Very small volume.
How does fluid move between ICF, ECF and TCF?
Osmosis
Hydrostatic pressure - pressure exerted by fluid against a boundary, such as the walls of blood vessels or the cell membrane
Active transport - sodium-potassium pump, play a role in maintaining the concentration gradients of ions across cell membranes
Explain how the body maintains a normal water balance.
Renal regulation - kidneys regulate water balance by adjusting urine volume and concentration based on the body’s hydration status, achieved using ADH
Thirst sensation
Sweating and respiration
GI tract regulation
Describe how water is lost from the body at rest.
Urination - kidneys continuously remove metabolic waste products and excess water from the bloodstream, resulting in the formation of urine
Sweating - helps regulate body temperature and remove metabolic waste products, occurs at slower rate
Respiration - water vapour is lost with each breath during respiration, slow rate
Insensible perspiration, which is the loss of water through the skin without noticeable sweating, also contributes to overall water loss.
Describe how water is lost during strenuous exercise
Decreased urination
Increased respiration
Increased sweating to regulate temperature
Increased insensible perspiration.
Explain the difference in the body’s response to the ingestion of one litre of water and one litre of isotonic saline.
While both water and isotonic saline are rapidly absorbed from the gastrointestinal tract into the bloodstream, the body’s response differs in terms of fluid distribution, electrolyte balance, and hormonal regulation.
Isotonic saline helps maintain electrolyte balance and does not cause significant changes in blood volume or plasma osmolarity compared to water ingestion
Describe the composition of blood
Plasma - liquid portion of the blood, contained water and plasma proteins
Buffy coat - white blood cells + platelets
Red blood cells
Describe the proportion of body weight blood volume represents in males
and females
Males - blood volume typically represents around 7-8% of total body weight
Females - typically around 6-7% of total body weight
due to differences in body composition and size
Describe how blood is distributed throughout the body
Arteries
Capillaries
Veins
Circulatory pathways
blood distribution throughout the body is regulated by the pumping action of the heart, the structure and function of blood vessels, and various physiological mechanisms that maintain blood pressure, flow, and perfusion to meet the metabolic needs of tissues and organs
Describe the composition of plasma, listing the main electrolytes and proteins
Liquid portion of blood
Water makes up approximately 90-92% of plasma volume, acts as solvent
Electrolytes - Na+, K+, Cl-, HCO3-, Ca2+, Mg2+, SO42-
Proteins;
Albumins - synthesised by the liver and maintain osmotic pressure
Globulins - various proteins involved in immune function, transport, and clotting
Fibrinogen - clotting protein synthesised by the liver
Nutrients - glucose, amino acids, lipids
Explain how plasma proteins are separated into albumin, fibrinogen and α, β and γ globulins
Electrophoresis
Exploit differences in protein size, charge, and other properties to isolate and identify specific protein fractions
