Chapter 1 Objectives

what is physiology?

Physiology is study of how living organisms’ work. The dynamic study of life through the vital functions of living organism and their organs, cells, and molecules.

What are the four fundamental properties of physiology

1.     only living organisms exchange matter and energy with the environment to continue their existence

2.     living organisms can receive signals from their environment and react accordingly

3.     what distinguishes a living organism is the life cycles of growth and reproduction

4.     the living organism can adapt to changing circumstances

general physiology

Focuses on cellular and molecular principles common to all organs and tissues.

medical physiology

Specifically deals with how the human body functions.

physiological genomics (functional genomics)

A branch that seeks to understand the roles genes play in physiology, linking molecular biology directly to organ function.

what is the master organizer

the genome ,controls molecules, cells, organs, and the way they interact

the reductionists road

To understand a gene product's function, a physiologist must retrace the "reductionistic road" to achieve an integrated understanding of how that gene functions at the level of the cell, the organ, and the whole body

cumulative effects

Physiological parameters, such as blood pressure, are under the control of many genes

polymorphisms (gene variant)

several genes can have a cumulative effect, such as producing high blood pressure

comparative physiology

Examines the differences and similarities between different species.

what were Claude Bernard discover

the conditions of the constancy of life: milieu extérieur and milieu intérieu

Milieu extérieur:

physically surrounds the whole organism

Milieu intérieu:

the tissues and the cells of the organism live

what is Milieu intérieu known as today

extracellular fluid

types of communication throughout the cell

1.     Takes places at the level of atoms or molecules

2.     Cell-to-cell messengers or intracellular messengers: H+, K+, and Ca+

3.     Complex chemicals

homeostasis

is the control of vital parameters (e.g., blood pressure, body temperature, plasma levels) to maintain a stable state.

what are tightly controlled parameters

arterial pressure and blood pressure

what are interior parameters

body temperature and plasma levels

List the disciplines that were given birth to by Physiology

biochemistry, biophysics, pharmacology, neuroscience, endocrinology, immunology, cell biology, and molecular biology.

what are the different branches of physiology

exercise physiology, general physiology, comparative physiology, medical physiology, Physiological genomics (functional genomics)

what are the mechanisms that make homeostasis possible

negative-feedback, positive feedback, and feed-forward

what is negative-feedback

reverses a change

The body's response opposes the initial disturbance, bringing the variable back toward its normal range.

What are the elements of negative feedback

a)     Sensor: system senses the vital parameter

b)    Comparator: system compares the input signal to an internal setpoint

c)     Controller: system multiplies the "error signal" to create an output signal

d)    Effector: An effector mechanism that opposes the original input to bring the parameter back toward the setpoint

example of negative feedback

↑ Body temperature → brain detects increase → sweating + vasodilation → ↓ body temperature

what is positive feedback

reinforces a change

The body's response amplifies the initial stimulus, causing the process to continue or become stronger until a specific endpoint is reached.

example of positive feedback

Cervix stretches → oxytocin released → stronger uterine contractions → more cervical stretching → more oxytocin

what is feed-forward

anticipates a change

The body responds before the variable changes significantly, based on an anticipated need.

what is an example of feed-forward

You are about to start running → your brain anticipates increased oxygen demand → heart rate and breathing rate begin to increase before your muscles develop a major oxygen deficit.

what is redundancy

The more vital a parameter is, the more systems the body has to regulate it. If one system fails, another maintains homeostasis

what is acclimatization

The short-term process of an organism adjusting to environmental changes.

An individual's ability to respond to environmental stress is also influenced by genetic factors

example of acclimatization

living in higher altitudes and sweating

what communication sources is cellular signaling (local)

intercellular, intracellular, and genomic

what are the communication cells for integrative signaling (long distance)

negative and positive feedback, feed forward, adaption, typically endocrine or neural

who created homeostasis

Walter Cannon

who created negative feedback

Sherrington

what are examples that cause homeostatic disruption

disease and stress

definition of a homeostatic control system

a system of interconnected cells which strive to maintain physiologic variables at a steady-state

what are examples of adaption with homeostasis

acclimatization, GAS, and Disease States

what is the inherently unstable mechanism of homeostasis

positive feedback, sometimes results in death…shock

What is GAS

general adaption syndrome (Hans Selye)

describes the body's general physiological response to prolonged stress.

alarm response, stage of resistance, and stage of exhaustion

what is alarm response

homeostasis lost

what is stage of resistance

returns toward homeostasis

what is stage of exhaustion

homeostasis impossible, damage/death

What is Disease States

occur when the body's normal physiological regulatory mechanisms are disrupted, overwhelmed, or unable to maintain homeostasis.

what is an example of disease states

heart failure

If the heart cannot pump enough blood:

·      ↓ cardiac output

·      → body senses ↓ blood pressure/perfusion

·      → activates sympathetic nervous system + RAAS

·      → ↑ heart rate + vasoconstriction + Na⁺/water retention

·      → attempts to maintain blood pressure and tissue perfusion.

equilibrium

A state that does not involve energy consumption

steady state

A state where a parameter value is constant because the body matches actions that lower the value with actions that raise it. Maintaining a steady state requires energy

Syncratistic vs. Antagonistic:

Mechanisms can work together (syncratistically) or in opposition (antagonistically)

what is an example of Syncratistic vs. Antagonistic:

insulin lowers blood glucose, while epinephrine and cortisol increase it

What is the difference between "General Physiology" and "Medical Physiology"?

General physiology (also called cellular and molecular physiology) focuses on principles common to the function of all organs and tissues at a cellular level

Medical physiology focuses specifically on how the human body functions as a whole and through its individual organ systems

According to Claude Bernard, why are the gastrointestinal tract and sweat ducts considered "outside" the body?

They are considered outside because they are not part of the "milieu intérieur" (the internal liquid environment of lymph and plasma that bathes the cells)

Describe the four components of a negative-feedback loop.

The loop requires a sensor to detect a parameter, a comparator to check that detection against a setpoint, a controller to generate an output signal based on the error, and an effector to take action that opposes the initial change

Is a well-regulated homeostatic parameter in a state of equilibrium?

No. A well-regulated parameter is in a steady state, which requires the constant consumption of energy to maintain constancy. Equilibrium involves no energy consumption

What is "redundancy" in the context of homeostasis?

Redundancy means that the body employs multiple regulatory systems for its most vital parameters. This ensures that if one system fails, others are available to maintain homeostasis

Why is the genome considered the "master organizer" in physiology?

The genome is the master organizer because it controls molecules, cells, and organs, as well as the ways they interact with one another

Describe how a hierarchy works in feedback loops using the endocrine system as an example.

In a hierarchy, one system controls another in a chain

For example, the hypothalamus (higher level) controls the anterior pituitary, which then controls the adrenal cortex (lower level) to release cortisol, which ultimately affects blood glucose levels