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Human Biology Unit 3 > Chapter 6.1 Regulation of the Composition of Body Fluids ✔ > Flashcards

Chapter 6.1 Regulation of the Composition of Body Fluids ✔ Flashcards

1
Q

What percentage of water is in infants, adult females, adult males and in old age?

A

Infants 75%
Adult females 50%
Adult males 60%
Old age 45%

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2
Q

What are the important roles fluids do in the body?

A

-Transporting substances from one area of the body to another
-Facilitating movement across membranes
-Being the site of chemical reactions

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3
Q

Which parts of the body contain water, and what is the approximate percentage of water in each?

A

-Brain (80-85%) (Most)
-Teeth (8-10%)
-Lungs (75-80%)
-Heart (75-80%)
-Liver (70-75%)
-Kidneys (80-85%) (Most)
-Muscles (70-75%)
-Blood (50%)
-Bones (20-25%)
-Skin (70-75%)

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4
Q

Define intracellular fluid

A

Fluid inside the cell (also known as the cytosol)

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5
Q

Define extracellular fluid

A

Fluid outside the cell

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6
Q

What does extracellular fluid contain?

A

-Blood plasma located within the blood vessels, which is also known as intravascular.
-Fluid between the cells, known as interstitial fluid, intercellular fluid or tissue fluid
-Fluid in specific body regions, known as transcellular fluid, which includes the fluid in the brain and spinal cord, eyes and joints and surrounding the heart

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7
Q

Can dissolved large materials t exchange through capillary walls?

A

No they are too large to move through the capillary wall; they instead tend to remain within the blood vessels

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8
Q

What separates plasma from interstitial fluid?

A

thin walls of the capillaries which allows relatively free exchnage of materials of the two

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9
Q

Define osmotic concentration

A

The concentration of solutes (also known as osmolarity)

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10
Q

Define osmotic pressure

A

The tendency of a solution to take in water

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11
Q

The greater the difference in osmotic concentrations between two solutions, the ________ the osmotic pressure

A

Greater

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12
Q

Define metabolic water

A

Water formed as a by-product of cellular respiration

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13
Q

What ways does the body lose body fluids?

A

-Via kidneys
-Through the skin
-Surface of the lung
-The alimentary canal

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14
Q

Define excretion

A

The removal of waste products of metabolism from the body

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15
Q

What several organs take part in excretion?

A

Lungs
-Involved in the secretion of carbon dioxide.
-Carbon dioxide and water are produced by all body cells during cellular respiration. The body cannot use carbon dioxide and it is carried in the blood until it reaches the lungs, where it is excreted. Some water is also lost from the lungs, in the form of water vapour, as we exhale.

Sweat glands
-Sweat glands in the skin secrete water containing by-products of metabolism such as salts, urea and lactic acid

Alimentary canal
-The alimentary canal passes out bile pigments that entered the small intestine with the bile.
-These pigments are the breakdown products of haemoglobin from red blood cells. They leave the body with faeces.
-The bulk of faeces is composed of undigested food material. These are not considered to be excretory products, as they have not been produced by the cells.

Kidneys
-The kidneys are the principle excretory organs.
-They are responsible for maintaining a constant concentration of materials in the body fluid.
-One of the most important wastes removed by the kidney is urea, which is produced in the liver during the breakdown of proteins

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16
Q

How does the kidney play a major role in regulating the composition of body fluids?

A

The kidney maintains a constant concentration of materials in body fluids by excreting waste products like urea and regulating the concentration of dissolved substances.
This allows the body to achieve homeostasis, especially for fluid and electrolyte balance

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17
Q

Define ureter

A

The tube that leaves each kidney and drains into the urinary bladder

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18
Q

Define urinary bladder

A

A hollow, muscular organ near the base of the abdominal cavity; collects urine from the two ureter

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19
Q

Define urethra

A

The tube that empties the bladder to the outside; in males, it also carries sperm

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20
Q

Define renal vein

A

Vein that takes blood away from the kidney

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21
Q

Define renal artery

A

Artery that takes blood to the kidney

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22
Q

Define nephron

A

The functional unit of the kidney; that is, it is the nephrons that carry out the kidney’s role in excretion and water regulation

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23
Q

Label the nephron diagram on page 138

A

1) Afferent arteriole
2) Efferent arteriole
3) Glomerulus
4) Glomerular capsule
5) Proximal Convoluted Tubule (PCT)
6) Loop of Henle (descending limb of Henle)
7) Distal Convoluted Tubule (DCT)
8) Collecting duct
9) Urine flows to the bladder

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24
Q

In the nephron, where does blood enter?

A

Under high pressure, blood enters the glomerulus

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25
In the nephron, where does filtration occur and what does it filter?
Occurs in the glomerulus Forces water and small dissolved molecules out of the blood and into the capsule. Large molecules and blood cells are retained in the blood
26
In the nephron, after the blood has been filtered where does it get collected?
Filtrate is collected by the glomerular capsule
27
In the nephron, where does reabsorption occur and what does it reabsorb?
- Proximal Convoluted Tubule - Distal Convoluted Tubule - Loop of Henle - Collecting duct Water and other useful substances are reabsorbed into the peritubular capillaries
28
In the nephron, where does secretion occur and what does it secrete?
- Proximal convoluted tubule - Distal convoluted tubule - Collecting duct It secretes some materials that need to be removed from the body. They are secreted into the kidney tubule from the peritubular capillaries
29
Define osmoreceptors
A receptor that is sensitive to osmotic pressure of body fluids
30
What process across a membrane allows reabsorption in the nephron?
-Reabsorption occurring at the proximal convoluted tubule and loop of Henle is by osmosis. -While reabsorption at the distal convoluted tubule and collecting duct is active reabsorption
31
Where is ADH produced and where is it released from?
Antidiuretic hormone is produced by the hypothalamus and released from the posterior lobe of the pituitary gland
32
What does antidiuretic hormone (ADH) control?
ADH controls water reabsorption in the kidneys by increasing the permeability of the distal convoluted tubule and collecting duct, helping maintain water balance in the blood.
33
What happens to the tubules permeability of water when ADH is high in blood plasma?
The tubules permeability to water increases and thus water is able to leave the tubule and enter the surrounding capillary network
34
What happens to the tubules permeability of water when ADH is low in blood plasma?
The tubules permeability to water decreases and thus water is not able to leave the tubule as much and enter the surrounding capillary network
35
Define aldosterone
A hormone that also plays a part in the regulation of water output. It is sometimes called the salt-retaining hormone.
36
What endocrine gland secretes aldosterone?
The adrenal gland, more specifically the adrenal cortex
37
What triggers the secretion of aldosterone by the adrenal cortex?
-Decrease in the concentration of sodium ions in the blood -Decrease in blood volume -Decrease in blood pressure -Increase in the concentration of potassium ions in the blood.
38
What part of the nephron does aldosterone affect and why?
The distal convoluted tubules and collecting ducts to increase the amount of sodium ions reabsorbed into the bloodstream and the amount of potassium secreted in the urine.
39
What process allows aldosterone to control sodium ad potassium movement in the kidneys?
Active transport via the sodium-potassium pump
40
What is the net movement of ions when aldosterone is active?
For every 3 sodium ions reabsorbed, 2 potassium ions are secreted
41
How does aldosterone affect water reabsoprtion?
It increases water reabsorption into the blood via osmosis due to increased sodium concentration
42
What part of the brain does osmoreceptors stimulate to stimulate the thirst response?
The thirst centre in the hypothalamus
43
How does drinking water help regulate body fluid?
Water absorbed from the alimentary canal enters the bloodstream, reducing osmotic pressure and increasing water levels.
44
Write a feedback loop on the regulation of water balance by the thirst mechanism when thirsty
Stimulus -Water concentration of blood plasma decreases -Osmotic pressure of the blood is increased. -Mouth becomes dry Receptor -Osmoreceptors in the thirst centre in the hypothalamus detect the rising osmotic concentration of the blood. Message -Osmoreceptors sends signals to the thirst centre Modulator -Stimulation of the thirst centre in the hypothalamus makes the person feel thirsty Message -Hypothalamus signals to stimulate drinking Effector -Skeletal muscles contract -Drink water Response -The fluid consumed is absorbed from the alimentary canal into the plasma in the blood. Feedback -Negative feedback -No longer thirsty -(As the blood circulates through the body, it enables the interstitial fluid and intracellular fluid to return to the normal osmotic pressure concentration.
45
Define dehydration
Excessive loss of water and accompanying salts from the body; results when the body loses more fluid than it takes
46
What are some symptoms that causes dehydration
-Sweating -Vomiting -Diarrhoea
47
What percentage of water loss shows symptoms of dehydration
2% of their normal body water
48
What are some symptoms of dehydration?
-Severe thirst -Low blood pressure -Dizziness -Headache
49
Define water intoxication
-A potentially life-threatening condition caused by drinking too much water when the amount of salt (and other electrolytes) in the body is low -Commonly caused by long bouts of intensive exercise during which electrolytes are not replenished and large amounts of water are consumed
50
What are some symptoms that causes water intoxication?
-Sweating: Lots of water and salts are lost via sweating and it is replaced with plain water
51
What are the signs of water intoxication?
Lightheadedness will first occur and then headache, vomiting and collapse may follow.
52
List three functions of water in the body
-Temperature regulation: Water helps maintain a stable body temperature through sweating and evaporative cooling -Transport medium: Water is the main component of blood plasma, enabling the transport of nutrients, hormones and waste products -Solvent for metabolic reactions: Water dissolved substances to allow chemical reactions (e.g. cellular respiration) to occur efficiently.
53
What organs has the greatest percentage of water?
The brain and kidney
54
True or false? There is more fluid in the plasma than in the cells.
FALSE!! Most fluid is inside the cells (intracellular fluid) not in the plasma
55
Describe osmosis
Osmosis is the passive movement of water molecules across a semi-permeable membrane from an area of low solute concentration to an area of high solute concentration aiming to reach equilibrium on both sides of the membrane
56
List the ways that fluid is: a) Gained b) Lost
a) Gained -Drinking liquids -Eating food (containing water) -Metabolic water (produced during cellular respiration b) Lost -Urine -Sweat -Water vapour (from lungs during breathing) -Faeces
57
Name the receptor that detect change in water content of the body, and state where are they located.
Osmoreceptors. Located in the hypothalamus
58
Is ADH secreted due to a high or low osmotic pressure?
Increase in osmotic pressure
59
What is the role of aldosterone in sodium regulation?
Aldosterone increase sodium reabsorption in the kidneys, helping maintain blood sodium levels.
60
Suggest why the proportion of water in a baby's body is larger than in their grandparent's body?
-Babies have more lean tissue and a high metabolic rate. Older adults have more fat, which holds less water
61
Explain why water toxicity can cause cells to swell
It dilutes sodium in the blood, creating a hypotonic (have a lower solute concentration and cause water to move into cells) environment, so water enters cells by osmosis and makes them swell
62
Why do homeostatic mechanisms focus on the kidneys rather than the lungs, skin or alimentary canal?
Because only the kidney can actively and precisely regulate water and solute levels in the blood
63
Draw a feedback loop on osmoregulation (Overhydration)
Stimulus -Increase in water concentration (decrease in blood osmolarity) Receptors -Osmoreceptors in hypothalamus, detect decrease in osmolarity -Baroreceptors in blood vessels, detect increase in blood pressure (blood volume increase with increase in water concentration Message -Hypothalamus sends nerve impulses to the posterior pituitary gland to control the secretion of ADH -Baroreceptors signals the adrenal cortex Modulator -The posterior pituitary gland decreases the secretion of ADH -The adrenal cortex decreases the secretion of aldosterone Message -Decrease in ADH secretion which reduced water absorption at kidneys -Decrease in aldosterone decreases the reabsorption of sodium Effector -Collecting ducts: Less permeable -Distal convoluted tubules: Excrete Na+ and water Response -More dilute urine is produced -Blood volume + pressure decreases Feedback -Negative feedback to decrease water concentration -ADH + aldosterone levels return to normal
64
Draw a feedback loop on osmoregulation (Dehydration)
Stimulus -Decrease in water concentration (increase in blood osmolarity Receptor -Osmoreceptors in hypothalamus detect increase in osmolarity -Baroreceptors in blood vessels detect decrease in blood pressure (blood volume decrease with decrease in water concentration) Message -Hypothalamus sends nerve impulses to the pituitary gland to control ADH levels -Baroreceptors sends signals to the adrenal cortex Modulator -Pituitary gland increase ADH secretion -Adrenal cortex increases the secretion of aldosterone Message -Increase in ADH = Increase water reabsorption at kidneys -Increase in aldosterone, sodium ion reabsorption increases Effector -Collecting ducts = More permeable -Distal convoluted tubules = Reduce sodium ions and water loss Response -More concentrated urine is produce -Blood volume and pressure increases Feedback -Negative feedback to increase water concentration -ADH and aldosterone levels return to normal
65
Why does Alex have a dry throat and feel thirsty after cross-country running?
He lost water through sweat and breathing, which concentrated his blood. Osmoreceptors trigger thirst, and reduced saliva (because osmoreceptors trigger water conservation, reducing water to salivary glands causing a dry throat).

Human Biology Unit 3 (17 decks)

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