Unit 4 – Anatomy & Physiology4.1 Digestive System

There are four major functions of the digestive systemo Breaks down food into smaller, more usable portions through

mechanical and chemical digestion Absorbs nutrients from digested material Absorbs water from digested material

o Separates the waste from the digested material and excretes it from the body

Digestion of food begins in the moutho Mouth – breaks down food through mechanical and chemical

digestion Mechanical digestion – physically breaking apart food

molecules Chemical digestion – using chemical compounds to break

bonds in food moleculeso Salivary Glands – secrete saliva, containing salivary amylase, to break

down carbohydrates and makes it easier to swallow food. After the stomach, food travels to the small intestine, and the pancreas and

liver also help in digestion.o Small intestine – long narrow tube attached to stomach that absorbs

nutrients through villi (fingerlike structures in the small intestine)o Pancreas – secretes insulin and enzymes to aid in fat digestiono Liver – Makes and secretes bile, a substance that also breaks down

fats Food then goes through the large intestine and begins to exit the body

o Large Intestine – absorbs any excess liquid in the digested materialo Rectum – tube connecting large intestine to anus that stores feceso Anus – where waste exits the body

1.2Circulatory/Excretory System There are six major functions of the circulatory system

1. Transport gases throughout body – oxygen is transported from the lungs to the cells and carbon dioxide waste is transported from the cells to the lungs

2. Transport nutrients to cells – for example, glucose, amino acids, fats, etc.

3. Remove waste – blood travels through the kidneys, creating liquid waste, which is then excreted through urination

4. Transport hormones – chemical signals used for many various bodily processes

5. Contains white blood cells that fight infection

6. Help maintain homeostasis – stabilizing pH of blood and bodily fluids and transporting heat

There are three main blood vessels of the circulatory system Arteries – the largest blood vessels, they carry blood AWAY from the heart

to the rest of the blood Veins – the second largest blood vessels, they carry blood from the rest of the

body BACK to the heart Capillaries – the smallest blood vessels, they carry blood to and from the

body’s cells. They are so thin that nutrients and gases can diffuse right through them.

The heart powers the whole circulatory system Heart – Muscle in the chest that pumps blood, keeping it moving to

every part of the body.

There are four main components of bloodo White Blood Cells – fight infectiono Red Blood Cells – Carries oxygen to cells and carbon dioxide away

from cellso Platelets – Clot blood to stop bleedingo Plasma – Clear, pale yellow fluid part

The Excretory System rids the body of liquid wastes and maintains an even balance of electrolytes in the body• System of the body that excretes• Accumulated wastes can cause damage to the body• Various parts of the body are responsible for this, including the

sweat glands, lungs, kidneys, and liver

a. Sweat Glands – Primarily a means of thermoregulation, but also excretes water, salt, and other wastesb. Lungs – Excrete carbon dioxidec. Liver – detoxifies drugs and alcohol and destroys some bacteria in the bloodThe main organs of the excretory system are the kidneys • Kidneys cleanse the blood and turn the waste into urine• The main structure located in the kidneys is called the nephron

oThere are millions in each kidneyoResponsible for forming urine

o The other parts of the excretory system include the ureters, bladder, and urethra

• Ureters – force the urine down away from the kidneys• Bladder – stores the urine to be released• Urethra – tube that allows urine to pass out of the body

4.3 Respiratory SystemThe main function of the respiratory system is to exchange gases into and out of the body• Provides us with the oxygen our body needs• Gets rid of carbon dioxide waste.• Works closely with circulatory system to exchange gases from our blood. Air enters the body through the nose or mouth

o Pharynx – the throat, food and air passes through hereo Larynx – the voicebox or vocal cordso Trachea – the tube, or windpipe, the leads to the lungs. A small flap of

skin, called the epiglottis, blocks food from entering the lungso Bronchi – two large tubes splitting off of the trachea that lead to the lungs

Air enters the lungs and then travels down the bronchioles into the alveoli• Lungs – organ that absorbs oxygen gas from the air• Bronchioles – tiny branches that split off from the end of the bronchi• Alveoli – clusters of tiny air sacs where gas exchange takes place

between the alveoli and capillaries• Diaphragm – a dome-shaped muscle at the bottom of the rib cage• These muscles contract and relax, allowing air to flow into or out of your lungs as you inhale or exhale

The respiratory system works with the circulatory system in order to maintain homeostasis.

4.4 Nervous System The Nervous System is the control system of the body

• Provides a way for the organ systems to communicate• Your body’s response system to internal and external changes in the

environment• Stimulus – change in the environment

The Nervous System is further split into the central and peripheral nervous systems

o Central Nervous System (CNS) – coordinates body functions. Includes the brain and the spinal cord.

o Peripheral Nervous System (PNS) – transmits information to and from the CNS. Includes networks of nerves that extend all around the body.

Neurons are specialized cells at are the main functional unit of the nervous system

o Transmit nerve impulses throughout the bodyo The cell body contains the cell’s nucleus and organelle’so Dendrites – branches of the cell that extend out to receive messages from

other cellso Axons – a long branch that transmits messages to other cellso Synapse – A tiny gap between neurons that the message travels betweeno Sensory Neurons – receive information from internal or external

environment through a receptor and carry signal to CNSo Motor Neurons – transmit impulses from brain or spinal cord to an

effector (muscle or gland) which then initiates a response.1.5 Musculoskeletal System

There are five main functions of the Skeletal System1. Provide our body with structure2. Provide protection for our organs3. Create blood cells in our bone marrow4. Store nutrients that our body needs5. Attachment to muscles for movement

2. Our bones are responsible for making new blood cells and providing us with nutrients

• Hematopoesis – the process of making new blood cells• Hematopoesis occurs in the bone marrow (the soft inner

tissue of the bone)• Bones undergo continuous remodeling and a variety of

nutrients are needed for this.

3. The Muscular System is attached to our skeleton and provide our body with movement

o Tendons – attach muscle to boneo Ligaments – attach bone to boneo Cartilage – dense, fibrous connective tissue that is

found between bonesThere are three main types of muscle found in our body

•Skeletal Muscle – Voluntary muscle attached to bones and provide the force needed to move the bones. •Smooth Muscle – Involuntary muscle that control many types of movement within the body (such as digestion)•Cardiac Muscle – Involuntary muscles that form the heart

4.7 Endocrine Systemo The Endocrine System consists of specialized glands that secrete

hormones• Glands -- specialized tissues that secrete hormones directly into the bloodstream• Hormone – chemical messengers that travel through bloodstream• Target Cells -receive the hormone and initiate a specific response

o The nervous and endocrine systems work closely together to provide cell communication

o The hypothalamus and pituitary glands are located in the brain (CNS) and secrete hormones

o Some chemicals function as both neurotransmitters and hormoneso Both systems are involved in the sympathetic nervous system

“fight or flight” responseo Many feedback loops incorporate both systems

1.7 HomeostasisHomeostasis is the regulation and maintenance of the internal environment.

• Internal stability and balance!• Conditions within the body must remain in a narrow range

o Temperatureo Blood glucoseo Heart rate

o Negative Feedback is when the brain sends instructions to counteract the change.

o Low blood pressure increasingo Secreting insulin when sugar is too higho Exhaling carbon dioxideo Sweating when body temperature is high

o Positive Feedback is when, for a short time, the brain brings the body away from ideal conditions

o Vomiting when illo Giving birth to a childo Creating extra platelets when getting a cut