Specialized Functions
• Digestive System: food in / solid waste out• Liver• Respiratory System: gas exchange, O2 in /
CO2 out• Excretory System: Nitrogen and other
soluble waste out, water, ion, and blood pressure balance
• Immune System: protection from invaders
Specialized Functions Cont.
• Circulatory System: Delivering things around the body
• Storage: Liver, muscle, fat and bone
• Reproductive System: A priority of the species
• Nervous System: Controls the endocrine system and expresses its priority
Priorities
• One individual (function) is more important than another
• Discrimination
• Priorities are necessary because resources are limited and circumstances change
Sensitivity to Blood Flow
• Brain: acutely sensitive
• Heart: also acutely sensitive
• Kidney
• Digestive system
• Skin
• Liver and digestive system
Barriers of the Body
• The interfaces with the outside world
• Exchange of atoms, molecules and heat
• Lungs
• Skin
• Digestive System
The Lungs
A passive bag with a large blood supply
When skeletal muscles expand the chest, air is sucked into the lungs
Gas Exchange
Diffusion
• A corollary of “Mother Nature’s Chaos” rule
• Everything goes downhill• From a high concentration to a low
concentration• Concentration is the number of
molecules (or ions) of a certain type per volume of water
Control of Breathing
• The brain controls how often the chest is expanded and how much the chest is expanded
• Information in: H+ concentration, also acute stress override
• Information out: Motor nerves to the diaphragm and intercostal muscles
• The brain must tell you to breath every time
Airways
• The autonomic nervous system (part of the brain) controls the opening and closing of the airways and the flow of blood to the lungs
• Parasympathetic (calm times): closes airways and reduces blood flow
• Sympathetic (acute stress): opens airways and increases blood flow
• Immune protection
Skin
• The surface of the body• Constant replacement and damage repair• Heat exchange, large variations in blood
flow• Molecules can also pass into the blood
through the skin eg. drugs, toxic molecules
• Immune protection
Skin
Heat Exchange and water conservation also effects blood pressure
Parasympathetic: more blood
Sympathetic: less blood
Digestive System
• Digestion: Big molecules into little molecules
• Absorption: Taking the little molecules and ions into the body.
• Inside the digestive system is outside the body
• Immune protection
Control of Digestion
• Parasympathetic: Increase movement, secretions, and blood flow
• Sympathetic: Decrease movement, secretions and blood flow
• The changes in blood flow are very large
• Priority of digestion is very low
The Liver and Kidney
Liver:Adjusting the molecular composition of the blood
Kidney: Water and ion balance
The Liver
Blood containing nutrients taken into the blood at the small intestine goes directly to the liver through the hepatic portal vein
Capillary bed Capillary bed
Small intestine (in) Liver (out)
Liver
• Nutrients that enter the blood at the small intestine must get out of circulation in the liver before entering general circulation
• The liver has the first opportunity to store • The liver also has the first exposure to drugs
and toxic compounds• More immune protection
Control of Liver
• Parasympathetic: promotes storage and increased flow of blood from the small intestine to the liver
• Sympathetic: Removes from storage and reduces blood flow from the small intestine to the liver
• Almost all hormones
Liver: Storage and Molecular Processing
• Blood also enters the liver from general circulation
• Nutrients enter the general circulation in the liver
• Molecules in general circulation are removed for reprocessing
• Many serum proteins and fats are made in the liver and released into circulation (eg. steroid binding proteins and cholesterol)
Balance:Ions and water
Ion concentration Blood Pressure
The ion concentrations of the blood must be “just right”
The more water in the body, the higher the blood pressure
The kidney controls the loss of water and ions from the body
Pressure and Volume
• When blood volume increases, blood pressure increases
• If you put in or remove ions from the body you must save or lose water to maintain concentrations “just right”
• The most important ion in this game is Na+
• H20 mover faster and easier than Na+
Control of the Kidney
• Parasympathetic: Increases blood flow to the kidney and increases urine volume
• Sympathetic: Reduces blood flow to the kidney and decreases urine volume
• Hormones– Antidiuretic Hormone (ADH) from the pituitary:
increases water recovery
– Mineralocorticoids from the adrenal: increases ion recovery
Storage
• We live in a world of feast and famine
• We store when nutrients are available and remove from storage when not available
• All tissues except for the brain store to some extent
• The liver stores sugar for the brain
Storage Tissues for the General Body
• Muscle: amino acid storage
• Fat: Fat
• Bone: Calcium (Ca++)
In addition to the liver
Skeletal Muscle
Movement of the skeleton is the only way that the brain can act on the world
Generation of heat is a by-product of movement: makes you warm-blooded
Skeletal Muscles
• Composed of thousands of individual fibers that shorten when sent a signal by a nerve
• Each fiber is controlled by a single motor nerve• One motor nerve can control many fibers• There are two types of fibers
– Tonic: deals with gravity
– Phasic: Deals with movement
Skeletal Muscle continued
• Most muscles are composed of a mixture of both types of fibers.
• Most muscles carry out both functions: movement and posture (gravity)
• Tonic fibers work more because gravity is always present
• The two types of fibers respond to some signals differently
Control of muscle
• Both respond to signals from their motor nerve by shortening
• Sympathetic nervous system and adrenalin – Phasic more efficient
– Tonic less efficient
If you are in danger you don’t want posture
getting in the way!!!
Hormonal Control
• Glucocorticoids: Shifts muscle into net degradation of proteins to provide amino acid carbon for making sugar in the liver and kidney- Phasic fibers more sensitive than tonic because they work less
• Insulin: Allows the fibers to take up sugar and amino acids- Tonic fibers more sensitive because they work more
Other Hormones
• Thyroid hormone: increases production and use of energy
• Growth hormone: Builds up muscle
• Testosterone: Makes exercise more useful in building up muscle
Control of Fat Cells
• Insulin: Uptake of nutrients- converts sugar to fat
• Adrenaline: release fat into circulation
• Many Drugs mobilize fat
Distribution of Fat in the Body
Are you a good fat or a bad fat?
HDLLDL
Oil and water don’t mix so fat must be packaged in a charged protein coat to move in the blood
High Density Lipoprotein Low Density Lipoprotein
Bone
Rigid structure against gravity – what muscles move
All blood cells are born in the marrow of bones
Storage of Calcium (Ca++)
Control of Bone
• Glucocorticoids: Demineralizes bone-More use less sensitive, less use more sensitive
• Calcitonin: From thyroid gland Ca++ out of bone
• Parathyroid hormone: From parathyroid gland Ca++ into bone storage
Control of Blood Cells
• Red Blood Cells: Erythropoietin controls how fast they are made in bone marrow
• White Blood Cells: – Insulin controls the uptake of nutrients – Glucocorticoids suppress – Cytokines: the chemical messages of the
immune system (many effects)
A priority of the species
Very expensive, especially to the female
“Mother Nature” built the compulsion to do it into the brain
We couple trading genetic material with reproduction
Change is Stress
• Stress requires adjustments
• Priorities are expressed in response to stress– Gravity– Starvation– Cold– Danger/anger