Week 1 Homeostasis/Human Physiology

What is physiology?

The mechanisms and processes that promote how living organisms function and maintain homeostasis.

What are the levels of organization in the human body?

Chemical, Cellular, Tissue, Organ, Body system, Organism.

What is the basic unit of structure and function in the body?

The cell.

What is differentiation in the context of cells?

The process by which unspecialized cells transform into specialized cells.

What are the four primary tissue types?

Muscle, Nervous, Epithelial, Connective.

What is muscle tissue specialized for?

Contracting and generating force.

What does nervous tissue consist of?

Cells specialized for initiating and transmitting electrical impulses.

What is the function of epithelial tissue?

Exchanging materials between the cell and its environment.

What does connective tissue do?

Connects, supports, and anchors various body parts.

What defines an organ?

Two or more types of primary tissue organized to perform a particular function.

How many body systems are essential for survival?

Eleven.

What is the role of the cardiovascular system?

Transport blood, oxygen, nutrients, and waste throughout the body.

What are the two major body fluid compartments?

Intracellular fluid (~67% of body fluid) and Extracellular fluid (~33% of body fluid).

What is the composition of intracellular fluid?

Fluid located inside the cells, differing significantly from extracellular fluid.

What is extracellular fluid? It includes what and what

Fluid outside cells, including blood plasma and interstitial fluid.

What is the extracellular matrix (ECM)?

A mixture of proteins, polysaccharides, and minerals that surrounds cells.

What are the two general functions of the ECM?

Provides a scaffold for cellular attachments and transmits information via chemical messengers.

What is homeostasis?

Maintenance of critical variables within a normal healthy range despite environmental changes.

What is dynamic constancy in homeostasis?

Short-term variability of variables but long-term predictability.

How does body temperature fluctuate in homeostasis?

It fluctuates around a setpoint, such as 37°C.

What happens to blood glucose levels after eating?

They increase and then return to their set point via homeostasis.

What is the importance of maintaining fluid composition across cell membranes?

It regulates cellular activity.

What is the function of cardiac muscle?

To contract and pump blood throughout the body.

Where is nervous tissue primarily found? 3

In the brain, spinal cord, and peripheral nerves.

What is the primary function of epithelial sheets?

To protect and facilitate exchange of materials.

What types of connective tissue exist? 4

Loose connective tissue, tendons, bone, and blood.

What is the significance of the kidneys in organ systems? 2

They are composed of various tissues that function in filtering blood and regulating body fluids.

What must a control system be able to do to maintain homeostasis?

Detect deviations from normal set-point, integrate information about variables, and adjust variables to restore to set-point.

What is a negative feedback system?

A common homeostatic control system where an increase or decrease in a regulated variable produces responses that modify that variable in the opposite direction.

Give an example of a negative feedback response.

A decrease in blood pressure leads to cardiovascular responses that increase blood pressure back to the normal level.

How do negative feedback systems operate?

They exist at many levels, from molecular to organ systems.

What is a positive feedback system?

A less prevalent system that accelerates a process or increases the production of a substance, contradicting the concept of homeostasis.

What happens in an unchecked positive feedback system?

It will not stop and can lead to harmful consequences.

What is set point resetting?

Homeostatic regulation of a variable around a new set point for a physiological purpose.

What is a reflex?

A specific, involuntary, non-premeditated response to a particular stimulus.

What are the major effectors in biological control systems?

Muscles and glands.

What is a hormone?

A chemical messenger secreted into the blood by cells of the endocrine system that can act on many different cells simultaneously.

How does the body detect blood pressure changes?

Through communication between cells/tissues/organs using chemical messengers.

What are the categories of chemical messengers? 4

Hormones, neurotransmitters, paracrine, and autocrine messengers.

What are gap junctions?

Physical linkages connecting the cytosol between two cells, allowing molecules to move directly from one cell to another without entering the extracellular fluid

the chemical messenger not actually being released from the cell producing it, but rather is located in the plasma membrane of that cell. When the cell encounters another cell type capable of responding to the message, the two cells link up via the membrane-bound messenger

juxtacrrine signaling

What is adaptation in the context of homeostasis?

A characteristic that favors survival in specific environments, which can be inherited.

What does acclimatization refer to?

The improved functioning of an existing homeostatic system due to prolonged exposure to an environmental change.

What is a circadian rhythm?

Rhythmical changes in body functions that cycle approximately once every 24 hours.

How do biological rhythms relate to homeostasis?

They add an anticipatory component to homeostatic control systems, enabling immediate activation of mechanisms before challenges occur. E.g., body temperature increases prior to waking up because metabolic processes function better in certain temperature

Why is homeostasis essential for health?

It is crucial for maintaining normal physiological functions, such as blood pressure, which is essential for brain function.

How do organ systems coordinate with each other?

They work together to control physiological functions, such as blood pressure regulation by the nervous, cardiovascular, and urinary systems.

Allows for the integration of physiological processes between cells, tissues, and organs.

information flow in homeostasis?

Controlled exchange of materials occurs between ____ and across ___ ___… and why is it important

It occurs between compartments and across cellular membranes, essential for processes like oxygen diffusion.

How are physiological processes governed?

By the laws of chemistry and physics, such as blood pressure being governed by a version of Ohm's Law.

What is required for physiological processes?

The transfer and balance of matter and energy, such as nutrient metabolism for energy.

How does structure relate to function in physiology? Give an example

Structure is a determinant of function, as seen in the alveoli of the lungs, which have a large surface area for oxygen diffusion.

3 components of negative feedback system

• Sensor - monitors magnitude of a controlled variable 

• Control centre - compares sensor’s input with a set point (compares what you have to what you are trying to get) 

• Effector - makes a response to produce desired effect