Human Phys Homeostasis Lab 3

Claude Bernard

Regulation of the internal environment was first described by French physiologist ____ in 1865

Homeostasis

Any self-regulating process by which biological systems tend to maintain stability while adjusting to conditions that are optimal for survival

Walter Cannon

The term homeostasis was coined by Harvard Neurophysiologist _____ in 1926.

Fight or flight and voodoo death

These terms were also coined by Walter Cannon

Dynamic constancy

Homeostasis is maintained by

Brain and hypothalamus

What makes up the control center for homeostatic regulation in the body.

Control center

Information from several systems must be integrated by the _____ in order to maintain values within the set-point range

Thermoregulation

Depends on dynamic constancy

Static constancy

Inanimate objects exhibit

Physical characteristic of the object

When a parameter, such as temp. of the object changes in response to changing the environmental temp., the return to the original temp. is dependent on the _______ and not a physiological response

Thermal conductivity

A property of a material that indicates its ability to conduct heat

0.138 W.m K

What is the thermal conductivity of pine wood

255 W.m K

What is the thermal conductivity of aluminum

0.49 W.m K

What is the thermal conductivity of muscle tissues

Set point

The normal range of values. Information from receptors and effectors are integrated by the control center to maintain values within the set point

Fever

What characterizes a change in hypothalmic set point, involves cytokines diurnal variation +, rarely exceeds 41 C, and complications are rare

Hyperthermia

What characterizes a failure thermoregulation, can exceed 41 C, can be detrimental, absence of diurnal variation

Negative feedback

All homeostatic mechanisms use ____ to maintain a constant value

Corrective mechanism

Negative feedback means that whenever a change occurs in a system, the change automatically causes a ____ to start, which reverses the original change and brings the system back to normal

Body temp., external environment, heart rate, blood pressure and volume

Examples of factors that influence a change in the homeostatic system include

Hemodynamics

Study of factors that effect blood flow through circulatory system

Postural changes

When standing still 60% blood volume pools in the veins of legs when standing still

Peripheral and central baroreceptors

Changes in pressure stimulate which receptors

Changes in heart rate and vascular resistance

Examples of changes in pressure

Peripheral baroreceptors

Specialized mechanoreceptors located in the carotid sinuses and aortic arch that detect blood pressure changes by sensing vessel wall stretch

Central baroreceptors

Specialized mechanoreceptors located in the carotid sinuses and aortic arch that detect changes in blood pressure, sending rapid, high-frequency action potentials to the medullary cardiovascular centers in the brain to regulate blood pressure and heart rate

Bradycardia

Slow heart rate

Vasodilation

Increase vessel diameter

Tachycardia

Fast heart rate

Vasoconstriction

Decrease vessel diameter

Cardiac ouput

Volume of blood leaving the heart in one minute

Posture and activity

Cardiac output changes with

CO=Heart Rate * Stroke Volume

What is the cardiac output formula?

Body mass, sex, fitness-level and health

Heart rate and stroke volume depend on what

Volume of blood leaving the heart

The volume of blood returning to the heart must equal

Hagen-Poiseuille statement

Flow is proportional to pressure difference and inversely proportional to resistance

Hagen-Poiseuille equation

Q=P1-P2/R

R=8nl(3.14)r4

For laminar flow in a tube, Poiseuilles law for resistance is defined as