Homeostasis

“Keeping things in balance”K.Seefloth

Definition

Homeostasis is: According to your Biology book: a

process by which organisms keep internal conditions relatively constant despite changes in external environments. Maintained by feedback loops.

Feedback Loop

Our body utilizes negative feedback loops the most.

This is when the amount of product of a reaction controls how fast (or slow) the reaction goes.

In negative feedback, change in the controlled value (body temperature, for example) initiates responses that bring the function of the organ back to within the normal range (shivering or sweating).

In other words…. Negative feedback loops are like a

thermostat in your house. If the temperature inside the house

drops below the point at which the thermostat is set and the thermostat turns on the furnace.

As the temperature within the house rises, the thermostat again senses this change and turns off the furnace when the programmed temperature is reached.

What we need to keep the same in our body:

Temperature (98.6 F) Blood pH (7.4) almost neutral Blood pressure (average 120/80) Heart rate (80 beats per minute) Blood sugar level Hydration/amount of water Amount of salts Amount of blood (2 pints per every

25 lbs)

What it really means (in English!)

The human body needs to maintain things like body temperature (98.6 F). If you get too hot or cold then your body will not thrive. Too hot and your brain will overheat and

“cook” Too cold and your body’s systems will

shut down

Each system of the body contributes some aspect to maintaining homeostasis (stable internal balance)

It is more than “the brain controls everything”!

Nervous System

Nervous System Central Nervous System

Brain and spinal cord: The brain is like your body’s central computer and the spinal cord is the network that the nervous system uses to send messages to and from the body.

Peripheral Nervous System All the nerves and neurons throughout

the body: Sensory neurons (cells) send signals to the brain and then the brain instructs motor neurons to move/react.

Autonomic Nervous System subdivided into the: Sympathetic – responds to stress and

danger. “Fight or Flight” response…release of adrenaline

Parasympathetic – dominant during sleep. Controls all functions that just “happen” like heart beating, breathing, and digestion.

Nervous System

Hypothalamus - controls body temperature with the following feedback loop: If too low, causes shivering of muscles

and reduced blood flow (blue skin) to create heat

If too hot, causes sweating and increased blood flow (red skin) to get rid of heat

Brain Stem - Controls heart rate with the following feedback loop: If too low, increases nerve impulses to

make heart beat faster If too high, decreases nerve impulses to

keep the heart rate at 80 beats per minute

Diseases/afflictions of the nervous system

Stroke Aneurism Brain Cancer Depression Bipolar disorder headaches

Activity

Lab: Fight or Flight ???

Doesn’t just break down food so you can eat!

Digestive System

Digestive System

The digestive system is made up of the digestive tract—a series of hollow organs joined in a long, twisting tube from the mouth to the anus—and other organs that help the body break down and absorb food

Organs that make up the digestive tract are the mouth, esophagus, stomach, small intestine, large intestine—also called the colon—rectum, and anus.

Inside these hollow organs is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to begin the process of digestion.

The digestive tract also contains a layer of smooth muscle that helps break down food and move it along the tract.

Two “solid” digestive organs, the liver and the pancreas, produce digestive juices that reach the intestine through small tubes called ducts.

The gallbladder stores the liver’s digestive juices until they are needed in the intestine.

The small intestine allows the broken down food (in the form of glucose and other molecules of life) to be absorbed by the bloodstream and transported to all parts of the body.

The large intestine allows water to be reabsorbed by the body. All leftover wastes are left over to be excreted out of the body.

Parts of the nervous and circulatory systems also play major roles in the digestive system.

Digestive System

Liver – Controls blood sugar level with the following feedback loop: If too low, converts stored glycogen

(glucose) into sugar If too high, removes sugar from the

blood and stores as glycogen

Diseases/afflictions of the digestive system

Diabetes Ulcers Acid reflux/heartburn Stomach or liver cancer Cavities/gum disease/root canal Tonsillitis Gall stones/gall bladder removal

Besides getting rid of wastes and filtering toxins out of the

blood, it also…..

Urinary/Excretory System

Urinary/Excretory System Works closely with the digestive,

circulatory and nervous systems. As the heart pumps blood around the

body, the blood carries fresh oxygen to various cells and organs, then picks up waste products like carbon dioxide, salt and urea.

There is an artery and a vein that runs into and out of each kidney to take the blood there and back.

As the waste products arrive, the kidneys perform a filtration process that removes hazardous toxins and products that the body can not use from water and nutrients that can be reclaimed and recycled.

The kidneys return the reclaimed water back to the body, but mix the waste products into a liquid waste compound known as urine.

The kidneys direct the urine to the bladder, where it is collected and held until it is either manually expelled or forced out by involuntary muscle contractions.

The excretory system takes advantage of sweating by providing waste liquids to accomplish the cooling effect.

Sweat is not pure water; instead, it is a solution of approximately 94 percent water and six percent waste products.

By excreting weak urine through the skin's pores, the excretory system can perform the dual functions of ridding the body of waste products while also keeping it cool.

Urinary/Excretory System

Kidneys - Controls amount of water and salt in body with the following feedback loop: If too low, retains water/salt and keeps

them from going to the bladder If too high, pushes more water and salt

into the bladder

Diseases/afflictions of the urinary/excretory system

Diarrhea UTI infection Colon Cancer Constipation Kidney stone Flatulence incontinence

Activity

Data Lab: Urinalysis

Besides controlling blood pressure and moving blood throughout the body it……

Circulatory/Cardiovascular System

Circulatory/Cardiovascular System

The main function of the circulatory system is to provide nutrients and oxygen to the various parts of the body, via the blood, which is circulated through the veins and arteries, like a giant transportation system.

Arteries carry the oxygenated blood from the heart to the cells and tissues, whereas veins return the oxygen-depleted blood from the cells to the heart.

The Two forms of Circulation

In systemic circulation, arteries collect the oxygen-rich blood from the heart and is transported to the body tissues. In the process, oxygen from the blood is diffused into the body cells; whereas carbon dioxide from the cells is diffused in the blood. This exchange of gases takes place with the help of capillaries that surround the body cells

The pulmonary circulation is a loop from the heart to the lungs. It is that portion, where deoxygenated blood from the heart is carried to the lungs and in turn, returns oxygenated blood to the heart.

The circulatory system works with the respiratory system and digestive system to supply oxygen and nutrients to the body.

Blood carries the messenger chemicals - hormones, secreted by the organs of the endocrine system. Thus, the circulatory system is also responsible for circulating hormones for proper communication between the body organs.

Circulatory/Cardiovascular System

Capillaries (smallest of blood vessels) - Controls flow of oxygen to cells and carbon dioxide from cells using the following feedback loop: If oxygen too low, gases flow from areas

of high concentration (capillaries)to low concentration (cells) to maintain levels

If too high, the opposite happens, gases flow from areas of high concentration (cells) to low concentration (capillaries).

Diseases/affliction of the cardiovascular/circulatory system

Heart attack High blood pressure Hemophilia Stroke Sepsis (infection) Bruises/contusions (hickey)

More than just breathing…

Respiratory System

Respiratory System

Air first enters your body through your nose or mouth, which wets and warms the air. (Cold, dry air can irritate your lungs.) The air then travels through your voice box and down your windpipe. The windpipe splits into two bronchial tubes that enter your lungs.

A thin flap of tissue called the epiglottis covers your windpipe when you swallow. This prevents food or drink from entering the air passages that lead to your lungs.

Except for the mouth and some parts of the nose, all of the airways have special hairs called cilia that are coated with sticky mucus. The cilia trap germs and other foreign particles that enter your airways when you breathe in air.

These fine hairs then sweep the particles up to the nose or mouth. From there, they're swallowed, coughed, or sneezed out of the body. Nose hairs and mouth saliva also trap particles and germs.

Within the lungs, your bronchi branch into thousands of smaller, thinner tubes called bronchioles. These tubes end in bunches of tiny round air sacs called alveoli.

Each of these air sacs is covered in a mesh of tiny blood vessels called capillaries. The capillaries connect to a network of arteries and veins that move blood through your body.

The muscle that helps the lungs breath is called the diaphragm. Breathing is something that happens passively, something that we don't even think about...that is unless it is something that becomes difficult to do.

Respiratory System

Lungs - Controls blood pH, amount of carbon dioxide in blood using the following feedback loop: If gets too low (acidic, pH below 7.4),

gets rid of excess CO2 (which caused the acid)

If gets too high (basic, pH above 7.4), retains more CO2

Diseases/afflictions of the respiratory system

Cold/flu Pneumonia Asthma Lung cancer Sinus infection allergies

Activity

Taking your pulse Lab: Measuring Lung Capacity

Besides keeping you upright….

Skeletal System

Skeletal System

The skeletal system offers protection, support, blood cell formation, stores minerals and energy and aids movement.

Calcium and phosphorus are stored within your bones.

Bones are considered to be living organs because they are made up of nerve, muscle and epithelial tissue, as well the connective tissue that binds everything together.

If you were to look at the cross section of a long bone, such as your femur, you would see a shaft that contains either red or yellow marrow. Red is newly produced marrow. As bones age, the red marrow converts into yellow. This special, yellow marrow is an energy source.

Within the bones, red and white blood cells are produced, along with platelets.

There is a fibrous sheath called a periosteum that contains blood vessels which supply oxygen and nutrients to the bone tissues.

Blood vessels get in and out of the bones by little openings called nutrient canals.

Skeletal System Bone Marrow - Controls blood levels

using the following feedback loop: 2 pints for every 25 pounds If too low (2 pints for every 25 pounds),

bone marrow produces necessary white and red blood cells.

Diseases/afflictions of the skeletal system

Broken/fractured bones Anemia (low RBC and/or iron) Osteo arthritis Torn ligament(s) Torn cartilage sprains

Yes, it helps us move, but it also….

Muscular System

Muscular System The muscles in our body are divided

into three classes: cardiac, smooth, and skeletal.

Muscles often work in pairs so that they can pull in different or opposite directions.

The cells that make up muscles contract & then relax back to their original size.

Tiny microscopic fibers in these cells compress by sliding past each other like a sliding door being opened & shut again.

At every joint, tendons and ligaments also help out. Muscles wouldn't be very useful alone because they don't directly connect to the bone, so even if they contract, they wouldn't be moving anything.

Muscles are connected to tendons, which are connected to the bones. When the muscles contract, they pull on the tendons, which in turn pull on the bones, and that causes movement.

But without ligaments, that movement wouldn't be too useful because it would not be directed movement.

Without ligaments, instead of bones bending or rotating about each other when muscles contract, they would slide by each other. Ligaments are what hold the bones together. They connect at the ends of muscles and keep them from slipping and sliding, and force them to bend.

The muscular system interacts with other systems of the body.

During inhalation, the muscles between the ribs relax, allowing the lungs to draw in air.

When you digest food, muscles in your esophagus interact with the digestive system.

Your nervous system tells your muscles when to move.

Even your skeletal system needs your muscular system because your muscles keep your bone structure intact

Muscular System

All muscles - Control body position using the following feedback loop: If muscle strength too low: Systems that

rely on the muscles to do the work necessary for homeostasis (heart, lungs, brain, digestive organs….) could not function

Diseases/afflictions of the muscular system

Muscular dystophy Multiple schlerosis (MS) Muscle cramps

Activity

Lab: Reaction Rates

This one is super important…

Lymph (Endocrine/Immune)

System

Lymph (Endocrine/Immune) System

The immune system is made up of many different cells, organs, tissues and substances within your body.

Each aid in eliminating foreign organisms from your body and protecting you from various diseases and illnesses.

These foreign organisms come in the form of viruses, bacteria, parasites and fungi. They are known as “microbes.”

First Line of Defense – The Skin The skin is thick and very hard to

penetrate and produces a variety of substances that are harmful to invaders.

The eyes, nose, and mouth are protected by fluids or sticky mucus that capture harmful attackers.

The respiratory tract has cilia, tiny hairs that remove particles.

Intruders that get as far as the stomach are up against a sea of stomach acid that kills most of them.

Second Line of Defense – White Blood Cells

There are several types of immune cells, each possessing specific duties and characteristics. Several travel through the body killing foreign substances as they find them.

Others patrol the gastrointestinal tract lining and blood vessels, safeguarding particular organs.

The lymphatic system, which includes the lymph nodes, the spleen, bone marrow and thymus gland, produces these cells and transports them throughout the body.

Lymph nodes and the spleen serve as filters designed to keep harmful organisms out of the blood stream. Most immune cells are produced in the bone marrow, the thymus or the spleen.

Lymph (Endocrine/Immune) System

Lymph Nodes - Controls against invaders such as bacteria and viruses Maintains/produces white bloods cells (B

cells, T cells) to battle against foreign cells in the body. Prevents major illnesses from taking over the body

Diseases/afflictions of the lymphatic system

Lymphoma (cancer) Leukemia (abnormal WBC) Any other infections acne

Activity

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