Physiology I & II Flashcards
(183 cards)
________ refers to the maintenance of nearly constant conditions in the internal environment and is the condition in which the body’s internal environment remains relatively constant within limits
Homeostasis
What are the 3 primary characteristics of the internal environment of an organism in homeostasis?
Contains optimum concentration of gases, nutrients, ions, water
Has optimal temperature
Has optimal pressure for health of cells
_______ is any stimulus that creates an imbalance in the internal environment
Stress
What type of feedback loop is defined by a response that reverses the direction of the initial condition?
Negative feedback loop
What are the 2 primary characteristics of negative feedback loops?
- Diminishes original change
- Stabilizing
What are the 2 primary characteristics of positive feedback loops?
Enhances original change
Destabilizing (can lead to runaway effects)
The stretch of the cervix during delivery sends signals that increase the force of uterine contractions which then increase the stretch on the cervix. This is an example of what type of feedback loop?
Positive
Baroreceptors are stretch receptors associated with the carotid system. When these sense an increase in arterial pressure, they send inhibitory signals to vasomotor receptors in the medulla. Heart pumping capacity is reduced and blood vessels dilate, leading to a decrease in arterial pressure. This is an example of what type of feedback loop?
Negative
An increase in the production of TSH releasing factor results in an increase in the release of TSH, which results in the release of more thyroxine, which results in a decrease in the production of TSH releasing factor. This is an example of what type of feedback loop?
Negative
______ is the degree of effectiveness with which a control system maintains constant conditions
Gain
How is gain calculated?
Correction/error
Adding 2 L of blood to an uncontrolled system and to a controlled system:
Uncontrolled system: Pressure rises from 100 to 175
Controlled system: Pressure rises from 100 to 125
Calculate the gain in this case.
Gain = Correction/Error = -50/25
Answer: -2
Baroreceptors (pressure receptors) in the carotid system sense changes (increases) in the arterial pressure. These baroreceptors send signals to the brainstem where the cardiac centers are located. A feedback system then activates a number of responses that result in a lowering of arterial presure. Two dogs are used in a study to test the effects of a drug that causes hypertension as a possible side effect. In one of the dogs the baroreceptor feedback system has been inactivated. In the dog with the intact feedback system, the arterial pressure increases from 100 to 110. In the animal with the inactivated control system, the pressure increases from 100 to 150. What is the effectiveness with which the baroreceptor system controls increase in blood pressure?
A. -1
B. -2
C. -4
D. -5
C. -4
The Na+/K+ ATPase pump utilizes energy derived directly from the breakdown of ATP. What type of transport is this?
Primary active transport
The Na+-Glucose co-transporter utilizes energy derived secondarily from concentration differences of molecular ionic substances created originally by primary active transport. What type of transport is this?
Secondary active transport
What is the most common cation in the extracellular environment?
Sodium
What is the most common cation in the intracellular environment?
Potassium
How is speed of action potential transmission affected by axon diameter and myelination?
Small diameter axons transmit more slowly than large diameter
Myelinated axons transmit more rapidle than non-myelinated
What type of action potential conduction requires myelination and is characteristic of the axon but not the cell body or dendrites?
Saltatory conduction
During skeletal muscle contraction, what specific event directly follows the opening of ligand-gated sodium channels in response to Ach binding?
Influx of sodium leads to end-plate depolarization (EPP)
During skeletal muscle contraction, what specific event directly follows the opening of voltage-gated sodium channels?
Sarcolemma action potential
Which band of skeletal muscle is formed by actin filaments and becomes narrower in width during contraction?
I band
Which band of skeletal muscle is equivalent to the length of the myosin filaments and does not change width during contraction?
A band
Which band of skeletal muscle is the part of the A band that is not overlapped by actin filaments and becomes narrower during contraction?
H band