Lecture 1: Human organism, homeostasis, feedback control

what is physiology?

Study and scientific investigation of the processes and function of living things

goals of physiology and why important

1. Understand normal values of function in the body and how these values are maintained within an appropriate narrow range (homeostasis) even in a changing environment

2. Be able to predict the body’s response to stimuli

Physiology is the foundation of clinical practice

sub-divisons of physiology

1. Pathophysiology: studies causes of abnormal conditions and the structural and functional changes that occur from diseases (ex: long covid)

2. Exercise physiology: studies the changes in structure and function from exercise (acute or chronic)

3. Cell physiology: studies the processes in cells

4. Systemic/s physiology: studies the function of organ systems

structural and functional organization

1. Chemical level: interaction of atoms (C, H, N, O, etc.) that form molecules (CO2, amino acids, DNA, proteins, etc.)

2. Cell level: smallest living unit

3. Tissue level: group of similar cells and the materials surrounding them (Epithelial, connective, muscle, nervous)

4. organ level: one or more tissues functioning together (etc: heart, lungs, liver, etc.)

5. Organ system level: group of organs functioning together

6. Organism level: any living thing (single cell bacterium to trillion of cells human)

*All levels are essential for the survival or organisms

Integumentary system

-Provides protection regulated temperature, prevents water loss, and helps produce vitamin D

-Consists of skin, hair, nails, and sweat glands

skeletal system

-Provides protection and support, allows movement, produces blood cells, and stores minerals (Ca and P) and fat

-Consists of bones, associated cartilages, ligaments, and joints

muscular system

-Produces movement, maintains posture, and produces body heat

-Consists of muscles attached to the skeleton by tendons

lymphatic system

-Removes foreign substances from blood and lymph, combats disease, maintains fluid balance, and absorbs fats from the digestive tract

-Consists of the lymphatic vessels, lymph nodes, and other lymphatic organs

respiratory system

-Exchanges O2 and CO2 between the blood and air and regulated blood pH

-Consists of the lungs and respiratory passages

digestive system

-Performs the mechanical and chemical processes of digestion, absorption of nutrients, and elimination of wastes

-Consists of the mouth esophagus stomach, intestines, and accessory organs

nervous system

-A major regulatory system that detects sensations and controls movements, physiological processes, and intellectual functions

-Consists of the brain, spinal cord, nerves, and sensory receptors

endocrine system

-A major regulatory system that influences metabolism, growth, reproduction, and many other functions

-Consists of glands, such as the pituitary that secrete hormones

cardiovascular system

-Transports nutrients, waste products, gases, and hormones throughout the body; plays a role in the immune response and the regulation of body temperature

-Consists of the heart, blood vessels, and blood

urinary system

-Removes waste products from the blood and regulated blood pH, ion balance, and water balance

-Consists of the kidneys, urinary bladder, and ducts that carry urine

female reproductive system

-Produces oocytes and is the site of fertilization and fetal development; produces milk for the newborn; produces hormones that influence sexual function and behaviors

-Consists of the ovaries, vagina, uterus, mammary glands, and associated structures

male reproductive system

-Produces and transfers sperm cells to the female and produces hormones that influence sexual functions and behaviors

-Consists of the testes, accessory structures, ducts, and penis

homeostasis

-maintenance of relatively constant conditions in the internal environment of the body

-Regulated variables (temperature, plasma K+, blood pressure) fluctuate around a set point to establish a normal range of values

set point

the ideal normal value of a variable

*Ex: normal BP at rest, increases for a still normal BP during exercise, decreases again for a still normal BP after exercise

negative feedback mechanism and components

regulates most systems in the body by resisting or counteracting a deviation from the set point (ex: if regulated variable increases, systems respond by making it decrease)

Major Components…

-Receptor: monitors the value of some variable

-Control center: establishes the set point (regions of brain)

-Effector: can change the value of variable (sweat glands)

stimulus

when a variable deviates from the set point and is detected by a receptor

positive feedback mechanism

-When a response to the original stimulus results in the deviation becoming even greater

-Unusual in most healthy physiology systems, except for a few instances like blood clotting, and several processes involved in the reproductive system

-Harmful positive feedback example: after sever blood loss, blood pressure decreases further impairing the heart’s ability to pump blood