Homeostatic regulation of gases and fluids

Question 1

Functions of body fluid

Answer 1

-transport substances from one area of body to another
-facilitating movement across membranes
-site of chemical reactions

Question 2

Distinguish between intracellular fluid and extracellular fluid
It’s components?

Answer 2

Intracellular fluid-fluid inside cell- the cytosol
Extracellular fluid: fluid outside the cells- intravascular, interstitial, transcellular

Question 3

Define intravascular fluid (part of extracellular)

Answer 3

blood plasma located within vessels

Question 4

Define interstitial fluid (part of extracellular)

Answer 4

fluid between the cells

Question 5

Define transcellular fluid (part of extracellular)

Answer 5

fluid in specific body regions i.e. in brain and spinal cord, eyes and joints and heart

Question 6

Define osmotic pressure/concentration
What is it’s function
What causes it to increase

Answer 6

the measure of the solute concentration in a solution and it’s tendency to take in pure solvent
- osmotic pressure causes water to move into the solution with the highest concentration (decrease water potent.)
-osmotic pressure increases due to decrease in water conc of blood

Question 7

How is fluid gained and lost in body

Answer 7

gained: food, metabolic water, drink
lost: lungs, skin, kidneys (urine), alimentary canals (faeces)

Question 8

Define excretion and the organs involved

Answer 8

removal of waste products of metabolism from the body
involvement: lungs, sweat glands, alimentary canal, kidneys

Question 9

How are lungs involved in excretion

Answer 9

Carbon dioxide excretion.
Blood carries CO2 to lungs to be excreted after cellular respiration.
Some water is also lost as water vapor during exhalation

Question 10

How are sweat glands involved in excretion

Answer 10

In skin. Secrete water containing by-products of metabolism such as salts, urea and lactic acid

Question 11

How are alimentary canal involved in excretion

Answer 11

passes out bile pigments that entered small intestines as a part of faeces. -not considered to be excretory products as they have not been produced by cells

Question 12

How are kidneys involved in excretion

Answer 12

the principle excretory organ, maintain constant conc of materials in body fluids via urination of body wastes (mainly urea).

Question 13

Outline the two roles of the nephron and kidney in urine production

Answer 13

function unit of kidney
produces urine in order to remove waste via excretion
filters blood

Question 14

Label the diagram of the nephron chapter 6 review questions
What does it do

Answer 14

removes waste from blood and regulate blood composition
what occurs ate the nephron
composed of:
-filtration
-reabsorption
-secretion

Question 15

Describe the role of the distal convoluted tubule and collecting duct in urine formation

Answer 15

reabsorption of water during movement of filtrate

Question 16

Relationship between diuretic and urination

Answer 16

diuretics increase urination

Question 17

Describe the feedback mechanism that operates to regulate an increase in osmotic pressure
How does ADH take part in water regulation

Answer 17

S-increase osmotic pressure/decrease in water conc
R-osmoreceptors in hypothalamus detect change in osmotic pressure
M- hypothalamus stimulates via nerve impulse release ADH from posterior pit/gland into blood stream
E- ADH work to increase permeability of DCT and CD, and increase the reabsorption of water into the blood
R-increase ADH decrease water in urine as water is reabsorbed into blood
F-increase in water conc/decrease osmotic pressure

Question 18

How does aldosterone take part in water regulation
Which part of the nephron aldosterone acts on?
What causes it’s secretion?

Answer 18

salt retaining hormone
-secreted by adrenal cortex
-acts on DCT and CD to increase Na ions reabsorbed into blood stream and K ions secreted in urine
-in response to: decrease conc of Na ions in blood, blood volume, or blood pressure
-increase in concentrations of K ions in blood

Question 19

Describe the feedback mechanism that operates to produce conscious feelings of thirst

Answer 19

S-increase in osmotic pressure/decrease in water conc
R-Osmoreceptors in thirst centre in hypothal. detect rising osmotic concentration of blood (or dry mouth)
M- thirst centre in hypothal. sends message to cerebral cortex
E-conscious feeling of thirst=drink person gets a drink
R-fluid consumed absorbed in alimentary canal into blood plasma then to tissue fluid
F-water conc increase/decrease osmotic pressure

Question 20

How is breathing controlled? in terms of muscles involved
How does message/impulse speed effect rate of breath?

Answer 20

-respiratory centre, located in medulla oblongata and pons receive info from receptors, hypothalamus, and cerebral cortex to regulate rate and depth of breath
-contraction of intercoastals stimulated by intercoastal nerves
-diaphragm contraction stimulated by phrenic nerve
-faster message impulses=faster breathing

Question 21

Define chemical equation for carbon dioxide dissolving in water

Answer 21

CO2+H2O–><—H2CO3—><—-HCO3+H

Question 22

function of chemoreceptors? where are the types of chemoreceptors located in regulation of gases? how do they function?

Answer 22

Stimulated chemoreceptors send nervous impulses to resp. centre
peripheral-within walls of aorta and carotid arteries (also known as aortic/carotid bodies) and are sensitive to changes in conc of oxygen, carbon dioxide, and hydrogen ions in blood plasma

central- located in medulla oblongata. sensitive to change in conc of carbon dioxide in blood and hydrogen ions in CSF.

Question 23

Describe the feedback mechanism for breathing that involves blood oxygen concentration
What are it’s limitations?

Answer 23

S-large decrease in O2
R-stimulates peripheral chemoreceptors in medulla oblongata=nerve impulses to resp. centre.
M-Respiratory centre. These impulses stimulate transmission of messages to
E- diaphragm + intercoastal muscles
R-breathing rate and depth increases.
F-Increase in O2
levels have to fall extremely low to take any stimulatory effect therefore its role in breath regulation is insignificant when in normal conditions.

Question 24

Describe the feedback mechanism for breathing that involves blood carbon dioxide concentration What chemoreceptors are most change sensitive?

Answer 24

Major factor role in breathing rate regulation.
Small increase in conc is enough to=marked increase in rate and depth of breathing
S-Increase in in CO2
R-stimulates peripheral chemoreceptors in walls of aorta and caroted arteries and central in medulla oblongata=nerve impulses to
M-the resp. centre. impulses stimulate transmission of messages to
E- diaphragm + intercoastal musclesvia phrenic and intercoastal nerves
R-breathing rate and depth increases.
F-decrease in CO2=decrease in H2

receptors in medulla oblongata most sensitive to this change, response however takes several minutes. the immediate response that occurs is produced by stimulation of aortic/carotid bodies stimulated by H increase

Question 25

Describe the feedback mechanism for breathing that involves blood pH How does hydrogen conc in blood plasma effect breathing? How is this response different to carbon dioxide stimulus?

Answer 25

S-Conc of Hydrogen ions increases with conc of CO2, decreasing pH
R-peripheral chemoreceptors in aortic/carotid bodies,
M-medulla oblongata
E-increase nervous stimulation to the intercoastal muscle/diaphragm (intercoastal and phrenic nerves)
R- rate and depth of breathing
F-decrease in H conc/increase in pH

the immediate response that occurs is produced by stimulation of aortic/carotid bodies stimulated by H increase faster than CO2

Question 26

Why is voluntary control of breathing possible? how does it occur?

Answer 26

protective mechanism and important in speech
cerebral cortex is able to by-pass medulla to send messages directly to intercoastal muscles and diaphragm

Question 27

What occurs when breath is held for too long?

Answer 27

CO2 builds up in blood plasma and receptors stimulate the inspiratory centre to send impulses to the inspiratory muscles

Question 28

Define hyperventilation, give its effects on the concentration of gases in the bloodstream and describe its possible consequences

Answer 28

Extremely rapid or deep breathing; may result in dizziness and even fainting, due to loss of carbon dioxide from blood and more oxygen than required
when underwater lack of CO2 causes body to assume that taking a breath is unnecessary so body will not register lack of oxygen

Question 29

Give the specific effect of ADH on the nephron

Answer 29

Controls the active reabsorption of water in the nephron by;
-increasing permeability of DCT and CD
-lowers water levels therefore decreasing urination

Question 30

What is the relationship between carbon dioxide and hydrogen in the blood?
How hydrogen concentration effecting breathing rate.

Answer 30

-CO2 dissolved in water, within blood plasma, it forms carbonic acid which dissociates to form H and bicarbonate ions in solution.
-H ions stimulate peripheral chemoreceptors which
send impulses to the respiratory centre/medulla oblongata
-stimulates diaphragm and intercostal muscles to contract more regularly
-increase in the breathing rate.