Week 4 - Intro to Physiology

Question 1

Define Physiolgy

Answer 1

Definition of physiology - the study of how the various parts of the body work together to achieve optimal functional capacity of the body.

Question 2

Homeostasis

Answer 2

Bodys operate to keep certain things caonstant so our reactions to the outside world can be optimal. Most important concept.

Question 3

Homeostasis in cell form…

Answer 3

Materials enter and leave body (gut, kidney)

Question 4

Homeostasis definition by Walter Cannon

Answer 4

• Constancy in an open system, such as our bodies represent, requires mechanisms that act to maintain this constancy.
• “Steady State” conditions require that any tendency toward change automatically meets with factors that resist change. (i.e., An increase in blood sugar results in thirst as the body attempts to dilute the concentration of sugar in the extracellular fluid.)
• The regulating systems that determine the homeostatic state consist of a number of cooperating mechanisms acting simultaneously or successively.(i.e., Blood sugar is regulated by insulin, glucagon, and other hormones
  that control its release from the liver or its uptake by the tissues.)
• Homeostasis does not occur by chance, but is the result of organized self- government.

Question 5

Organ Systems in Review

Integumentary
Musculoskeletal
Respiratory
Digestive
Urinary
Reproductive
Circulatory
Nervous and Endocrine
Immune

Answer 5

• • Integumentary - Skin, defense, heat control, important to have constant temp
• Musculoskeletal
• Respiratory - Lungs, exchange gasses, CO2 and O2
• Digestive - Take in nutrients
• Urinary - Kidneys, salt and water balance in body
• Reproductive - survival of species
• Circulatory - mass transport of O2 and CO2
• Nervous and Endocrine - allow us to act to outside environment
• Immune - Defense against outside world

Integumentary, resperatory, and urinary control the blood.

Question 6

Integration of organ systems

Answer 6

• Surrounded by integumentary system with openings for intake and output.
• Kidneys condition blood for ion and water concentrations

Question 7

Teleological Approach to understanding physiology

vs

Mechanistic approach

Answer 7

Example: Why does glucose leave the blood and enter cells?

Tele: Glucose enters the cell to provide energy for cell activities

Mech: Glucose enters cells in response to insulin’s effect on mobilizing glucose transporters to the cell membrane.

Question 8

Homeostatcis is controlled by…

Answer 8

A control system.

Input signal (reads the body) -> Controller (compares to set point) -> Output signal (effector- makes a change)

Question 9

Controlled Variables

Set Point

Steady State

Equilibrium

Answer 9

Things that ahve to be maintained within narrow ranges to keep body in homeostasis

“Controlled Variables” (i.e., blood glucose, arterial pressure, body temperature)

Terms:

Set Point (established by body, if not at set point something happens)

steady state (variable is not changing, but things can still happen… bucket example)

equilibrium (input matches output)

Question 10

Negative Feedback System

Primary Disturbance

Compensatory Response

Answer 10

• If something acts on setpoint to make it go up or down… then there is something that happens to counteract that change. The compensating mechanisms bring it back up to the set point

Ex. if MAP (mean arteriol pressure) goes down

barroreceptors read the pressure, then the medulla reads the low pressure and sends out information through the NS to heart and vascular syst to increase blood pressure

Primary disturbance : drop in pressure

Compensatory response : Raise in pressure

Question 11

Positive Feedback System

Answer 11

It reenforces the primary disturbance - it is bad.

• Positive Feedback Systems: act to reinforce a change in a variable acceleration of the change and lead to an “explosion” and breakdown of the homeostatic system.

Question 12

Reflexes

Neural and hormonal

Answer 12

Reflexes:

1. neural
   signal :: sensory receptor :: afferent neurons :: Integrating Center ::
   efferent neurons :: effector organs (i.e., muscle, gland)
2. hormonal (same components except the neural connections are replaced
   by humoral signals that are carried by chemicals in the blood)

Question 13

Chemical Messengers:

Endocrines (hormones)

Neurocrine (neurotransmitters)

Paracrines (local chemical messengers)

Autocrines (locally secreted chemical messengers)

Answer 13

E. Chemical messengers:

• endocrines (hormones), carried in the blood to distant target cells
• neurocrine (neurotransmitters), released from nerves acting on neighboring cells
• paracrines (local chemical messengers) that acting on neighboring cells
• autocrines (locally secreted chemical messengers) that act on the secreting cell

Question 14

What is the outline of homeostasis and controls

Answer 14

Question 15

Orthostatic hypotension

Answer 15

Pts who have this do not have enough blood volume, when they stand body tries to compensate by increaseing HR but not enough blood gets to heart and they have decreased cardiac output and the pt faints.

Question 16

What happens to a pt working outside on a hot, dry day?

Answer 16