Exam 1: Homeostasis

Question 1

What is homeostasis?

Answer 1

Conditions in the body that are maintained at near-constant conditions

Question 2

Who coined the term “homeostasis” in 1929?

Answer 2

Walter Cannon

Question 3

Schmidt says when we give anesthesia we do what to the body?

Answer 3

Anesthesia takes a lot of control systems offline; us as CRNAs need to take over the work that the nervous system normally does

Question 4

What goes ___ must come ___?

Answer 4

In; Out

Question 5

What is input?

Answer 5

Food

Question 6

What is output?

Answer 6

Output energy and “waste products”
Energy = work, heat, and potential energy
Waste products = CO2, H+, H2O, Urea, solid waste

Question 7

What is the internal environment?

Answer 7

Everything under the skin

Question 8

How many cells does the body have?

Answer 8

35 trillion

Question 9

How does anatomy relate to physiology?

Answer 9

Form fits function

Question 10

What is the main homeostasis example? Explain what occurs.

Answer 10

Peripheral circulatory beds
Blood flows into the artery –> arteriole; fluid comes in from the vascular system and delivers nutrients; byproducts are removed through the veins and venules.

Question 11

T/F. The amount of blood flow depends on the metabolic demands of tissues.

Answer 11

True

Question 12

T/F If the blood flow picks up in the arteriole end, it will slow down in the venule end.

Answer 12

False. When blood picks up in the artery, it is also picked up in the vein because the metabolic demands have increased and byproducts need to be removed faster d/t the metabolic demands

Question 13

What are 4 other examples of homeostasis?

Answer 13

Kidneys - maintaining blood pressure, ensuring pH is normal
GI - replacing nutrients in the blood
Lungs - blood gas regulation
2 heart pumps - sharing a wall and making sure we have gas exchange in the lungs and at the peripheral part of the cardiovascular system

Question 14

What are negative feedback loops?

Answer 14

A major control system in the body that “senses” a positive or negative change in the system and the body reacts and has the opposite effect.

Question 15

What is an example of a negative feedback loop with inc. CO2?

Answer 15

Inc. CO2 causes increased ventilation which leads to a decrease in CO2

Question 16

What are 4 examples of a negative feedback loop with dec. MAP?

Answer 16

1. Increased sympathetic output
2. Decreased parasympathetic output
3. Increased AVP/ADH released from pituitary gland
4. Decreased ANP

Question 17

What are positive feedback loops?

Answer 17

A major control system in the body “senses” a change and the body responds by AMPLIFYING this change; can be good or bad and detrimental

Question 18

What are 2 examples of positive feedback loops?

Answer 18

1. When a woman is in labor, the uterus contracts and pushes the baby towards the cervix causing the fetus to stretch the cervix. Oxytocin is released from the brain and causes the smooth muscle to relax and cause more contractions which lead to more stretching of the cervix until the baby is born.
2. When a blood vessel gets injured there is going to bleeding. Endothelial cells will expose coagulation factors and promote plt plug formation and activation of the coagulation cascade. This leads to increased coagulation and normally the body would stop this when the bleeding stops. If bleeding doesn’t stop, we can have blocked vessels

Question 19

If positive feedback loops don’t stop, what can they lead to?

Answer 19

Vicious cycles

Question 20

Name and explain 4 main examples of vicious positive feedback cycles:

Answer 20

1. Sepsis/Necrosis
   - widespread infection
   -cells dying and things in cells are released and killing other cells
2. Severe acidosis
   - CNS is affected so much that our respiratory drive gets worse and we become more acidotic
3. Severe hemorrhage
   - Dec. in MAP leads to decreased coronary blood flow and decreased CO and even further decrease in MAP
4. Renal Inflammation/Hyperfiltration
   - nephrons die and create a larger workload on the remaining nephrons leading to more death

Question 21

What is compensated shock?

Answer 21

When negative feedback is working well

Question 22

What is decompensated shock?

Answer 22

When positive feedback leads back to death and negative feedback is insufficient

Question 23

How much blood can someone lose and still recover?

Answer 23

20%