Chapter 4

Priorities: An Organization Chart of the Body

Organization

• Cells

• Tissues

• Organs

• Organ Systems

• The Body

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

Change Requires Adjustment

• Gravity

• Food and water

• Temperature

• Danger

• etc

Expression of Priorities

Access to blood, access to resources

Sensitivity to Blood Flow

• Brain: acutely sensitive

• Heart: also acutely sensitive

• Kidney

• Digestive system

• Skin

• Liver and digestive system

Controlling Priorities

Barriers of the Body

• The interfaces with the outside world

• Exchange of atoms, molecules and heat

• Lungs

• Skin

• Digestive System

Barriers of the Body

• Constant replacement

• Damage repair

• Immune protection

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

A “Captured” water Environment

Compartmentalized

Esophagus

Stomach

Small intestine

Large intestine

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+

Kidney

Ion, water and blood pressure balance

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

Fat Cells

. OIL AND WATER DON’T MIX!

Control of Fat Cells

• Insulin: Uptake of nutrients- converts sugar to fat

• Adrenaline: release fat into circulation

• Many Drugs mobilize fat

Fat also produces hormones

• Adiponectin, Leptin, cytokines

• Obesity

• Diabetes

• Athrosclerosis

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

Drugs influence Priorities

• Coffee

• Nicotine and cocaine

• Alcohol

• Antihistamines

• Birth control pills

• Etc.