Human Body

Systems Part 1

The levels of organization in the

human body:

Connective and Epithelial Tissue

•Connective Tissue– Provides support for the body and

connects its partsExample: blood, bone, cartilage, fat

•Epithelial Tissue– Covers interior and exterior body

surfaces; protects, absorbs, filters, and secretes

Example: skin, blood vessels

Muscle and Nervous Tissue

•Muscle Tissue-provides movement with help from the skeleton (contracts) Example: heart, biceps, stomach

•Nervous Tissue–Transmits and processes information in the body

Example: brain, sciatic nerve

TissuesOrganOrgan SystemsHuman body has 11 organ systems:

– Nervous– Integumentary– Respiratory– Digestive– Excretory– Skeletal– Muscular– Endocrine– Reproductive– Lymphatic– Immune

Homeostasis

• All 11 body systems interact to maintain homeostasis.– The Nervous system coordinates the body

functions to maintain homeostasis.

• Feedback inhibition/Negative feedback: a stimulus produces a response that opposes the original stimulus.– Ex: body temperature and home heating unit

Fun Facts about… the Nervous System

• The number of neurons in our body is more than the number of stars in the Milky Way.

• The speed of message transmission to the brain can be as high as 180 miles per hour.

• The human brain alone consists of about a 100 billion neurons. If all these neurons were to be lined up, it would form a 600 mile long line.

Nervous System

• Function: controls and coordinates functions throughout the body. Responds to external and internal stimuli.

• Neurotransmitters – chemicals used by a neuron to transmit an impulse across a synapse to another cell

• Nervous cells are called neurons.– 3 types:

• Sensory (sends msgs TO brain)

• Motor (sends msgs FROM brain)

• Interneurons (connects neurons)

Typical Neuron

Explaining Nerve impulses

Two Divisions of Nervous System

1) Central Nervous System (CNS)– Relays messages,

processes and analyzes information

– Includes brain and spinal cord

• Brain: Cerebrum (voluntary activity, thinking, learning, judgement), cerebellum (coordinates muscles), brain stem (involuntary activity i.e. breathing, heart rate)

2) Peripheral Nervous System (PNS)

– Receives information from environment and relays commands from CNS to organs and glands.

– Includes nerves and associated cells not part of CNS

How is the spinal cord like a telephone line?

PNS is so BIG – It’s divided into 2 divisions

1) Sensory: transmits impulses from sense organs to the CNS**Eyes, ears,

tongue, etc..5 Senses:

Touch, Taste, Smell, Hearing, Sight

2) Motor: transmits impulses from CNS to muscles or glands•Divided into 2 divisions:

1)Somatic NS: regulates activities under conscious control

Ex: moving skeletal muscles

2)Autonomic NS: regulates activities that are automatic, or involuntary

Ex: breathing

Nervous System

Peripheral Nervous System

Central Nervous System

SensoryMotor

Somatic Autonomic

Drugs and the Nervous System

• Stimulants: Increase heart rate, blood pressure and breathing rate. Increase neurotransmitters– Ex: amphetamines, cocaine, caffeine

• Depressants: slow down heart and breathing rate, lower blood pressure, relax muscles and relieve tension– Ex: alcohol, heroin

Fun Facts about… the Integumentary System

• It contains your body’s largest organ… your skin.

• An average adult's skin spans 21 square feet, weighs nine pounds, and contains more than 11 miles of blood vessels.

• The skin releases as much as three gallons of sweat a day in hot weather

• In a lifetime, the average person sheds enough skin cells to fill an entire 2 story house. In one minute, you can lose between 30,000 and 40,000 skin cells.

Integumentary System

• “To Cover”• Includes skin, hair, nails, and glands• HAIR AND NAILS:

– Made of keratin (protein)– Hair: covers the body, gives warmth,

protects eyes and nose, develops from hair follicles

– Nails: develop at the nail root

Skin

• Function: barrier between infection and injury; regulates body temperature; protects from UV rays; removes waste

• 2 layers:– Epidermis: outer layer (keratin/melanin)

• No blood vessels• Made of flat dead cells

– Dermis: beneath epidermis• Sweat glands: reduce heat• Oil glands: keep skin flexible and waterproof

Fun facts about… the Muscular System

• The busiest muscles in your body are the eye muscles, which approximately move more than 100,000 times in a day

• Muscles cannot push, they can only pull.

• There are approximately 640 muscles in the body.– The largest is your gluteus maximus.– The smallest are in your middle ear.

Muscular System

• ALL a muscle can do is contract (get shorter)– Ex: moving forearm

(uses muscle pairs)

• 3 Types:– Skeletal– Smooth– Cardiac

Skeletal Muscle• Attached to bones• Voluntary

movements• Striated• Controlled by the

CNS

Smooth Muscle

• Involuntary• Not striated• Controlled by the

PNS• Found in walls of

stomach, blood vessels, intestines, etc;

Cardiac Muscle

• In heart• Striated (like

skeletal)• Involuntary (like

smooth)• Controlled by the

PNS

Muscular System Cont’d

** The more you use it the stronger it gets

** Tendons connect muscle to bone** Muscles work in pairs – one

contracts while the other relaxes

Fun Facts about…the Skeletal System

• A baby is born with 300 bones, but an adult only has 206.

• 54 of those bones are in your hands.

• Humans and giraffes have the same number of bones, but giraffes’ vertebras are much longer.

Skeletal System• Function: supports

the body, protects internal organs, provides for movement, stores mineral reserves, and provides a site for blood cell formation as well as a place for muscles to attach

• FACT: There are 206 bones in the human body.

Two parts of the skeletal system

1) Axial Skeleton: skull, vertebral column, rib cage**Protects organs**

2) Appendicular skeleton: bones of arms and legs, pelvis, and shoulder area**Involved in movement**

Bones

• Bones are made of living and nonliving tissue

• Red marrow- makes new red blood cells, white blood cells, and some platelets

• Early bone starts as cartilage.• Ossification – process of bone formation

– Osteoblasts: build up bone– Osteoclasts: break down bone

• Why do we need both??

Joints

• Ligaments hold bones together at joints• Joint-place where two bones meet• 3 TYPES:

– Immovable: no movement (ex: skull)

– Slightly Movable: restricted movement (ex: bones in lower leg, joints between vertebrae)

– Freely Movable: movement in one or more direction(ex: Ball-and-socket, hinge, pivot, and saddle joints)

Fun Facts about… the Digestive System

• We eat about 500kg of food per year. 1.7 liters of saliva is produced each day.

• The stomach must create a new lining of mucous every 2 weeks, otherwise it would digest itself.

• An adult stomach can hold 1.5 liters of food.

• In an average person, it takes 8 seconds for food to move through the esophagus, 1-3 hours in the stomach, 3-5 hours in the small intestine, and 3-4 days in the large intestine.

Why is it important?

The digestive system’s

function is to help convert

food into simpler molecules that

can be absorbed and used by the cells of the body.

Step 1. The Mouth

• Teeth– Chewing begins

the process of mechanical

digestion• The physical

breakdown of large pieces of food into smaller pieces called a BOLUS

• Saliva– Begins the

process of chemical digestion

• The enzyme AMYLASE breaks down carbohydrates

Step 2. The Esophagus

• Food tube that connects the mouth to the stomach

• The bolus moves through the esophagus by PERISTALIS– Muscles in the walls of

the esophagus contract in waves, which pushes the bolus until it reaches the stomach

“Help Me”! My food went down the wrong pipe!

Step 3. The Stomach

• Chemical Digestion:– The stomach contains hydrochloric

acid– This acid activates an enzyme,

PEPSIN•Pepsin is responsible for breaking down

protein

– Chemical digestion of carbohydrates stops while in the stomach

The Stomach

• Mechanical Digestion:– Stomach muscles

contract to churn and mix the stomach acid and food to create CHYME

– After about an hour of churning, the chyme begins to flow into the small intestine

Step 4. The Small Intestine

• Most of chemical digestion and absorption of food you eat occurs in the small intestine.

• As chyme enters the S.I., it mixes with enzymes and digestive juices from the pancreas and liver.

How does the Small Intestine Work?

• In the lining of the small intestine, there are folds that are covered in fingerlike projections called VILLI and microvilli

• Carbohydrates and protein products are absorbed into the capillaries in the villi.

• After the small intestine, the only things remaining are water, cellulose, and other indigestible substances

Step 5. The Large Intestine

• The large intestine’s main role is to remove water from the undigested material that is left.

• The concentrated waste material that remains after the water has been removed passes through the rectum and is eliminated from the body.

Accessory Structures:The Pancreas

• Functions:– Produces hormones

that regulate blood sugar

– Produces enzymes that break down carbohydrates, proteins, lipids, and nucleic acids

– Neutralizes stomach acid that allows the enzymes to be effective

Accessory Structures:The Liver

• Organ located just above and to the right of the stomach

• Function:– Produces BILE

• Helps dissolved droplets of fat found in the small intestine

• Extra bile is stored in the gall bladder

Digestive System