BPK 105 Study Guide - Final Guide: Bicarbonate Buffer System, Distal Convoluted Tubule, Ph

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browncricket987

27 Apr 2018

School

Simon Fraser University

Department

Biomedical Physio & Kines

Course

BPK 105

Professor

Ryan Dill

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Module 12 - Review Questions - Part 7

10. Describe the homeostatic control of blood pH in response to an increase in blood pH

(alkaline, H+ concentration decreases). Include all three mechanisms of control, and a

brief discussion of the time course for each type of response mechanism. [5 marks]

Blood pH refers to a measure of the concentration of of H+ ions in the blood. When blood pH

increases as a result of a decrease in H+ concentration, three factors can help to restore

homeostasis: the kidney, the lungs and buffers.

- The distal convoluted tubules, which are part of a kidney nephron, lower the amount of

HCO3- that gets reabsorbed into the blood, as well as lower the amount of Hydrogen

ions being secreted into the urine.

- The process in which HCO3- is reabsorbed into the blood and in which H+ is secreted

into the urine occurs at a quicker rate as the blood’s pH decrease below its normal

range; the rate at which these processes occur decreases as blood pH increases above

its normal range, causing blood pH to decrease to its normal range.

- This results in a lower blood pH, because there are less HCO3- in the blood that can

form bonds with Hydrogen ions and there are less Hydrogen ions that get eliminated

from the blood. Compared to the respiratory system, the kidney does not respond as fast

to pH changes.

- The respiratory system responds quickly to changes in blood pH.

- With an increase in blood pH, the brain’s respiratory control center causes the person to

respire more slowly and more shallowly, causing the rate at which carbon dioxide leaves

the body to be decreased.

- This leads to more carbon dioxide in the blood, which after reacting with water, forms

carbonic acid.

- The carbonic acid ultimately dissociates, leading to an increase H+ concentration in the

blood and a decrease in blood pH.

- Buffers resist pH changes when an acid or a base is added to a solution that contains a

buffer; buffers can be composed of a weak acid and its conjugate base or a weak base

and its conjugate acid.

- Three divisions of buffers in the fluids of the body help to resist pH changes. These

include the bicarbonate buffer system, proteins, and the phosphate buffer system.

- When blood pH is too high, buffers release Hydrogen ions, increasing the amount of

Hydrogen ions in the blood, helping to keep the blood pH within a narrow range of

values. For the bicarbonate buffer system, carbon dioxide can form carbonic acid after

combining with water; the carbonic acid, in turn, can break down to form a bicarbonate

ion and a hydrogen ion. With an increase in carbon dioxide concentration, more carbonic

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Document Summary

Module 12 - review questions - part 7: describe the homeostatic control of blood ph in response to an increase in blood ph (alkaline, h+ concentration decreases). Include all three mechanisms of control, and a brief discussion of the time course for each type of response mechanism. Blood ph refers to a measure of the concentration of of h+ ions in the blood. When blood ph increases as a result of a decrease in h+ concentration, three factors can help to restore homeostasis: the kidney, the lungs and buffers. The distal convoluted tubules, which are part of a kidney nephron, lower the amount of. Hco3- that gets reabsorbed into the blood, as well as lower the amount of hydrogen ions being secreted into the urine. This results in a lower blood ph, because there are less hco3- in the blood that can form bonds with hydrogen ions and there are less hydrogen ions that get eliminated from the blood.

Related Questions

3. The second stage of urine formation is called _________. Cells lining the proximal convoluted tubules (PCTs) have special projections called _________ which increase their surface area, thus enabling the PCTs to transport about 70% of filtrate back into blood. 4. When a person is dehydrated, their blood volume and blood pressure are too low. Two hormones reduce the loss of sodium and water from the body during dehydration by concentrating urine to prevent further water loss. The first hormone is secreted by the adrenal cortex and is called __________; this hormone stimulates sodium retention by nephrons. The second hormone is released by the posterior pituitary gland and is called _________; this hormone cause water retention by nephrons. 5. ___________is the waste product of cellular respiration (ATP synthesis). This waste product must be eliminated from the body because it becomes toxic at high levels. This waste product combines with water in blood to form carbonic acid, which is then converted into bicarbonate ions (HCO3-) and hydrogen ions (H+). Hydrogen ions lower blood pH, causing it to become too acidic. Kidneys are able to sense high H+ levels in blood and actively transport hydrogen ions (and other toxic blood borne chemicals) from blood into urine during ___________, the third stage of urine formation.

turquoisecat964

. The kidneys contain millions of _________, which are the smallest functional units of the kidneys since each one can make urine from blood.

2. There are 3 stages in urine formation. The first stage is called____________; during this stage, blood pressure pushes water and small solutes out of a ball of capillaries called the __________ into the first part of the renal tubule called the _________ _________.

3. The second stage of urine formation is called _________. Cells lining the proximal convoluted tubules (PCTs) have special projections called _________ which increase their surface area, thus enabling the PCTs to transport about 70% of filtrate back into blood.

4. When a person is dehydrated, their blood volume and blood pressure are too low. Two hormones reduce the loss of sodium and water from the body during dehydration by concentrating urine to prevent further water loss. The first hormone is secreted by the adrenal cortex and is called __________; this hormone stimulates sodium retention by nephrons. The second hormone is released by the posterior pituitary gland and is called _________; this hormone cause water retention by nephrons.

5. ___________is the waste product of cellular respiration (ATP synthesis). This waste product must be eliminated from the body because it becomes toxic at high levels. This waste product combines with water in blood to form carbonic acid, which is then converted into bicarbonate ions (HCO3-) and hydrogen ions (H+). Hydrogen ions lower blood pH, causing it to become too acidic. Kidneys are able to sense high H+ levels in blood and actively transport hydrogen ions (and other toxic blood borne chemicals) from blood into urine during ___________, the third stage of urine formation.

6. Urine and blood differ in composition. In a healthy person, blood contains _________ , __________, and _________ but urine DOES NOT these materials.

7. Urine moves from the kidneys down the ureters into the bladder due to __________, a form of motility wherein _________ muscle tissue in the ureteral walls undergoes rhythmic waves of contractions.

8. The kidneys are located in the ___________ cavity; ureters conduct urine to the urinary bladder which is located in the pelvic cavity behind the symphysis joint of the _________ bones.

9. The three major systems which participate in the excretion of cellular wastes from blood include: the __________ system which eliminates urea and excess electrolytes like sodium; the ___________ system which eliminates water and salt; and the ____________ system, which eliminates carbon dioxide.

10. When the bladder is full, the _____________ reflex is initiated. During this reflex, the bladder walls contract and the ________ ________ sphincter, a circular structure made of _______ ______tissue, relaxes. Upon sensing an urge to urinate, a person can consciously contract their _______ _______ sphincter, a circular structure made of ________ ________ tissue - this stops the flow of urine out of the bladder and into the urethra until the time is convenient to urinate.