Intro to Physio - Definitions & Questions

Anatomy

the study of structure.

Physiology

the study of function.

Homeostasis

maintenance of a stable internal environment by keeping regulated variables within an acceptable range.

Set point

the target value around which a regulated variable is maintained.

Dynamic process

a process in which physiological variables are continuously adjusted rather than held at one fixed value.

Respiration

obtaining oxygen, removing carbon dioxide, and releasing energy from foods.

Digestion

breakdown of food substances into simpler forms.

Absorption

passage of substances through membranes and into body fluids.

Assimilation

changing absorbed substances into chemically different forms.

Circulation

movement of substances in body fluids.

Excretion

removal of wastes produced by metabolic reactions.

Levels of biological organization

molecule → macromolecule → organelle → cell → tissue → organ → organ system → organism.

What is the relationship between anatomy and physiology?

Anatomy describes structure, while physiology explains function; structure and function are interdependent.

Why can dysfunction at a lower level of organization affect higher levels?

Higher levels depend on the proper structure and function of lower levels.

Is homeostasis about maintaining every variable at one exact value?

No. Homeostasis maintains regulated variables within an acceptable range around a set point.

Why is homeostasis described as dynamic?

Physiological variables are constantly changing and being adjusted rather than remaining perfectly fixed.

Negative feedback

a regulatory mechanism that reduces the initial disturbance by counteracting the deviation.

Positive feedback

a regulatory mechanism in which the response amplifies the initial stimulus.

Sensor

detects and continuously monitors a regulated variable.

Controller

compares sensory information with the set point and initiates a corrective response when a deviation occurs.

Effector

carries out the corrective action that helps restore the regulated variable toward its acceptable range.

Thermoregulation

regulation of core body temperature.

What is the primary mechanism of physiological regulation?

Negative feedback.

What does negative feedback do to the original disturbance?

It counteracts or reduces the disturbance.

What does positive feedback do to the original stimulus?

It amplifies the stimulus.

Does positive feedback maintain homeostasis?

No. It accelerates a process toward a specific endpoint.

Why does positive feedback require an external stop?

Because the response amplifies the original stimulus rather than counteracting it.

What are examples of positive feedback?

Blood clotting and childbirth.

What are the three major components of a negative-feedback system?

Sensor → controller → effector.

During thermoregulation, what detects changes in temperature?

Peripheral thermoreceptors in the skin and central thermoreceptors in the brain.

What is the controller during thermoregulation?

The hypothalamus.

What is an effector involved in cooling the body?

Sweat glands.

Why is shivering in response to a low body temperature an example of negative feedback?

Shivering generates heat to counteract the decrease in body temperature.

Rising estrogen causes increased hormone release that ultimately triggers ovulation. What type of feedback is this?

Positive feedback because the response amplifies the original hormonal stimulus.