integumentary system organ...
TRANSCRIPT
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Integumentary System
• Forms the external body covering • Composed of the skin, sweat glands, oil glands,
hair, and nails • Protects deep tissues from injury and
synthesizes vitamin D
Organ Systems
• Composed of the brain, spinal column, and nerves
• Is the fast-acting control system of the body • Responds to stimuli by activating muscles
and glands
Integumentary
Nervous
Organ Systems
• Composed of bone, cartilage, and ligaments • Protects and supports body organs • Provides the framework for muscles • Site of blood cell formation • Stores minerals
Skeletal
• Composed of muscles and tendons • Allows manipulation of the environment,
locomotion, and facial expression • Maintains posture and produces heat
Muscular
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Endocrine System
• Composed of all the cells and glands that secrete hormones.
• Hormones are are transported by the blood and have effects on certain target tissues.
• They regulate a variety of functions such as growth, metabolism, reproduction, electrolyte balance,…
CardioVascular System
• Composed of the heart and blood vessels
• The heart pumps blood • The blood vessels transport blood
throughout the body • Important for transport of gases,
nutrients, waste products, defense mechanisms, ….
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Organ Systems
• Composed of red bone marrow, thymus, spleen, lymph nodes, and lymphatic vessels
• Picks up fluid leaked from blood vessels and returns it to blood
• Disposes of debris in the lymphatic stream • Houses white blood cells involved with
immunity
• Composed of the nasal cavity, pharynx, trachea, bronchi, and lungs
• Keeps blood supplied with oxygen and removes carbon dioxide
Respiratory
Lymphatic/Immune
Organ Systems
• Composed of the oral cavity, esophagus, stomach, small intestine, large intestine, rectum, anus, and liver
• Breaks down food into absorbable units that enter the blood
• Eliminates indigestible foodstuffs as feces
Digestive
• Composed of kidneys, ureters, urinary bladder, and urethra
• Eliminates nitrogenous wastes from the body • Regulates water, electrolyte, and pH balance
of the blood
Urinary
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Reproductive System
• Composed of prostate gland, penis, testes, scrotum, and ductus deferens
• Main function is the production of offspring • Testes produce sperm and male sex hormones • Ducts and glands deliver sperm to the female
reproductive tract
• Composed of mammary glands, ovaries, uterine tubes, uterus, and vagina
• Main function is the production of offspring • Ovaries produce eggs and female sex hormones • Remaining structures serve as sites for fertilization and
development of the fetus • Mammary glands produce milk to nourish the newborn
Male
Female
Maintaining Life
The organization of the body, depends on specific conditions of several environmental factors such that cells, tissues, organs can work and integrate successfully with each other:
Examples include :
! Nutrients ! Oxygen ! Water ! Temperature ! Atmospheric Pressure
And why ?
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Homeostasis
! Walter Canon, an American Physiologists, introduced the concept of Homeostasis in 1930.
! Homeostasis (stability of the internal world) is the overall process in which the body’s internal environment remains within certain physiological limits despite drastic outside changes
Because the cells that make up the body require a stable internal environment in order to function properly !
Homeostasis
So what is that internal world, environment of the body that needs to be controlled ?
It is the fluid that surrounds the cells !
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Total body water in humans ( and most animals ) is located in different ‘compartments’ . For a 70 kg person, this calculates out to
! extra-cellular fluid (ECF) o plasma (fluid in blood vessels): ~ 3 liters o interstitial fluid (in-between the cells) : ~ 11 liters
! intra-cellular fluid (ICF) : ~ 28 liters
Total water content ~ 3+11+28 =42 Liters
Where are the Body Fluids Located ?
Distribution of Body Fluids
28 L 11 L 3 L
A 70 kg person has thus about 42 kg of water…. Or 60 % of body weight is water content.
Note : females have more water content than males
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Cell membrane
Distribution of Body Fluids
Homeostasis and Cell Membranes
Barrier between plasma and Interstitial Fluid are the walls of the smallest blood vessels that supply the cells ( the capillaries) .
These capillaries are very permeable to fluids and smaller molecules but restrict passage of blood cells and proteins.
Plasma and Interstitial Fluid thus tend to have similar composition with respect to ions and smaller molecules !
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The Cell membrane however provides a selective permeable barrier between Interstitial Fluid and Intra-Cellular Fluid and thus functions as a gate keeper. It determines what goes in and out of the cell.
Optimal functioning of a cell depends on optimal conditions of the environment that surrounds the cell, e.g., the ECF
The state of the ECF ( e.g. the plasma ) determines the state of the ICF !
Homeostasis and Cell Membranes
Electrolyte Distribution is distinct
Due to the characteristics of the cell membrane, fluids inside and outside the cell have distinct different chemical composition with respect to cations and anions !
• What can you tell about the distribution between Sodium and potassium ?
• Between Chloride and proteins ?
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Electrolyte Distribution
The unequal distribution of the electrolytes between extracellular and intracellular compartments is essential for the function and well being of cell.
It should be of no surprise then to learn that the control and maintenance of these unequal distributions is one of the major homeostatic processes constantly at work in order to keep the body in a “happy” state of being !
• What organ is of major importance in this control of ‘electrolytes’ within the extracellular fluid ?
• What is the purpose of doing a blood analysis ?
Examples of Other Homeostatic values
Potassium 3.5 - 5.0 mmol/L < 1.0 or > 15
Oxygen 35 - 40 mm Hg < 10
CO2 35 - 40 mm Hg > 80
pH 7.35 - 7.45 < 6.9 or > 8.0
Body Temp. 37 C > 44
Glucose 75 - 85 mg/dl < 20
Normal Range Lethal range
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Homeostasis
What happens if homeostasis is disrupted?
! Loss of cellular organization and function ! Results in diseased state ( = sickness)
! Loss of tissue, organ organization and function ! Organ system failure …… death !
If this disruption spirals out of control?
Control Mechanisms
Disruption of Homeostasis leads to an unstable internal environment and results in disease or even death if not corrected.
The body has many Control mechanisms and regulatory systems that oppose the forces of stress and bring the internal environment back into balance.
We are constantly challenged by stress stimuli that create an imbalance in the internal environment.
Such systems are known as feedback systems.
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Elements of a Feedback system
Receptor
Integrating Center
Effector
Afferent pathway
Efferent pathway
Types of Feedback Systems
o Positive Feedback
" the response causes an increase in the action of the original stimulus
" the variable keeps moving away from its previous value
o Negative Feedback " the response reverses the action of the
original stimulus
" the variable returns to the ‘ideal’ , normal value
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Negative Feedback System
Para
met
er
(such
as B
lood
Pre
ssur
e)
Time
Stimulus normal range
Response
Stimulus
Response
Negative Feedback System
Example : Room Temperature Regulation
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Negative Feedback System
Human Example : Body Temperature Regulation
Negative Feedback System
Insulin release
Glucagon release
Example : Blood Glucose Regulation
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Positive Feedback System
Para
met
er
Time
Stimulus normal range
Response
Response Response
In Positive feedback, the system moves away from homeostasis and normal range is lost. However, it speeds up the process.
Positive Feedback System
Example : Blood clotting
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Activation of Feedback Systems
Nervous system Endocrine System
• Acts via neurons • Fast acting • Short lasting
• Acts via hormones • ‘Slow’ acting • Long lasting
Two major organ systems are constantly at work to monitor deviations from homeostasis and to control the disruptions via feedback systems.
However, all body systems come into play when it comes to homeostasis. (why for example would the skeletal system come into play to maintain daily homeostasis ?)
Activation of Feedback Systems
Keep in mind that homeostasis is a state of equilibrium where opposing forces are at work but kept in balance.
It is a Dynamic equilibrium — the body requires constant and continual adaptation.
It is the essence of Physiology : physiological systems work to restore balance and physiology tries to unravel and understand the mechanisms at work.
Failure in homeostasis results in disease or death. Failure to understand the mechanisms at work results in bad medicine.
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Bad Medicine: trepenation
In ancient times, it was believed that piercing the head would not only cure migraines and epileptic seizures, but could also be used on mentally ill people to ‘allow the bad spirits to escape’.
Bad Medicine: mercury to the rescue
For centuries people believed that Mercury could treat pretty much anything and everything. Mercury is actually extremely toxic and its use most likely helped to accelerate the ‘homeostatic imbalance’. In medieval times, it was also used to fight STDs. There was thus a ‘silver’ lining in its use : the "cure" usually resulted in one less person with syphilis in the world.