SystemsChapters 35-40

Chapter 35: The Nervous System•Function: Controls and

coordinates functions throughout the body and responds to internal and external stimuli

•Structures:▫Neurons▫Brain▫Spinal Cord

Nervous System• Neurons – cells that transmit

electrical signals called impulses

• Structure of a neuron:▫Cell body—contains the nucleus and much of

the cytoplasm.▫Dendrites—short, branched extensions that

spread out from the cell body.▫Axon—long fiber that carries impulses away

from the cell body.▫Myelin sheath—insulating membrane that

surrounds the axon

Nervous System•Brain – Contains approximately 100

billion neurons and has a mass of about 1.4 kg.

• Structures: ▫ The cerebrum—responsible for the voluntary, or

conscious, activities of the body.▫ The cerebellum—located at the back of the skull and

coordinates and balances the actions of muscles.▫ The brain stem—connects the brain and spinal cord.

Two regions: pons and the medulla oblongata Controls blood pressure, heart rate, breathing and swallowing

▫ Thalamus and hypothalamus Thalamus—receives messages from all of the sensory receptors

throughout the body and then relays it to the proper region of the cerebrum.

Hypothalamus—control center for hunger, thirst, fatigue, anger and body temperature.

Nervous System•Spinal Cord•Main communications link

between the brain and the rest of the body.

•Thirty-one pairs of spinal nerves branch out from the spinal cord, connecting the brain to all the different parts of the body.

•Reflex—quick, automatic response to a stimulus.▫Allows the body to respond immediately

Nervous System• Sensory Receptors (5 types)1. Pain Receptors –respond to chemicals released

by damaged cells2. Thermoreceptors – detect variations in

temperature (skin, body core, & hypothalamus)3. Mechanoreceptors – sensitive to touch,

pressure, stretching of muscles, sound and motion

4. Chemoreceptors –sensitive to chemicals in the external environment (nose and taste buds)

5. Photoreceptors – sensitive to light (eyes)• Video

Chapter 36: Skeletal System•Function: supports the body,

protects internal organs, provides for movement, stores mineral reserves, and provides a site for blood cell formation

•Structures:▫Bones▫Ligaments

Chapter 36: Skeletal System

• Bones• A solid network of living cells and protein fibers

that are surrounded by deposits of calcium salts.• Periosteum—is a tough layer of connective tissue

surrounding the bone.• Haversion canals—network of tubes running

through compact bone containing blood vessels. • Bone marrow—red and yellow

▫Red—produces red blood cells, some kinds of white blood cells and platelets

▫Yellow—is made up primarily from fat cells

Chapter 36: Skeletal System• Ligaments – tough connective tissue that

hold bones together• Joint – place where one bone attaches to another bone• Immovable joints—allow no movement. Bone are

interlocked and held together▫ Bones in the skull

• Slightly moveable joints—small amount of restricted movement. ▫ Between adjacent vertebrae

• Freely moveable joints—movement in one or more directions▫ Ball-and-socket, hinge joints, pivot

joints and saddle joints

Chapter 36: Muscular System

•Function: Movement, however, the type of movement is dependent on the location and type of muscle present

•Structures:▫Skeletal Muscles▫Smooth Muscles▫Cardiac Muscles

Chapter 36: Muscular System•Skeletal Muscles—usually attached to

bones.•Are large, striated, have many nuclei, and

vary in length from 1 mm to about 30 cm.

•Often called muscle fibers.•Responsible for voluntary

movements.

Chapter 36: Muscular System• Smooth muscles—Usually not

under voluntary control.• Spindle-shaped, has one nucleus,

and is not striated.• Found the walls of hollow

structures such as the stomach, blood vessels, and intestines.

• Move food through your digestive tract, controls the way blood flows through your circulatory system, and decrease the size of your pupils in bright light.

• Can function without nervous stimulation.

Chapter 36: Muscular System

•Found in just one place in the body—the heart.

•Is striated like skeletal muscle—cells are smaller.

•Usually have one nucleus, but may have two.

•Not under the direct control of the CNS and are connected to their neighbors by gap junctions.

Chapter 36: Muscular System

•How muscles and bones interact•Skeletal muscles are joined to bones

by tough connective tissues called tendons.

•Most skeletal muscles work in opposing pairs.▫When one muscle contracts the other

relaxes.▫Muscles of the upper arm.

•A controlled movement requires contraction by both muscles.

Chapter 36: Integumentary System

•Function: Serves as a barrier against infection and injury, helps to regulate body temperature, removes waste products from the body, and provides protection against ultraviolet radiation from the sun.

•Structures: ▫Skin▫Hair▫Nails

Chapter 36: Integumentary System

•Skin: two layers1. Epidermis2. Dermis

•Epidermis—outer layer of the skin▫The outside of the epidermis is made up of

dead cells.▫Inner layer is made up of living cells.

•Dermis—inner layer of skin▫Interacts with other body systems to

maintain homeostasis by helping to regulate body temperature.

Chapter 36: Integumentary System

• Hair and Nails• Basic structure is keratin• Hair

▫Protects the scalp from ultraviolet light.

▫Provides insulation from the cold.▫Prevent dirt and other particles from entering the body.

• Nails ▫Grow at an average rate of 3 mm per

month.▫Grow from an area of rapidly dividing

cells. known as the nail root.

Chapter 37: Circulatory System•Functions: Transportation system of the

body and is involved in respiration, nutrition, waste removal, immunity, and thermal regulation

•Structures:▫Heart▫Vessels▫Blood

Chapter 37: Circulatory System• The Heart is a hollow organ that

is about the size of your clenched fist.

• Contracts on average 72 time a minute, pumping about 70 mL of blood with each contraction.

• Each side contains two chambers— the upper chamber, which receives blood is the atrium, and the lower chamber, which pumps blood out of the heart, is the ventricle.

• The Heart

Chapter 37: Circulatory System• Circulation through the heart• Blood enters the right atrium of the heart, from

the rest of the body, through the superior or inferior Vena Cava.

• From the right atrium it moves to the right ventricle where it is pumped to the lungs through the pulmonary arteries.

• The now oxygen-rich blood returns to the heart through the pulmonary veins and enters the left atrium.

• Lastly, the blood moves down into the left ventricle were it is pumped to the rest of the body through the aorta.

Chapter 37: Circulatory System•Vessels•3 types

▫Arteries—carry blood away from the heart Main artery leading away

from the heart is the Aorta▫Capillaries—have one layer of cells where

diffusion and exchange of materials takes place▫Veins—carry blood back to the heart

Blood reenters the heart through the inferior and superior Vena Cava

Chapter 37: Circulatory System• Blood• Red Blood Cells—transport

oxygen▫ Hemoglobin—iron-containing

protein that binds to oxygen in the lungs and transports it.

• White Blood Cells—guard against infection, fight parasites, and attack bacteria.

• Platelets—plasma proteins that make blood clotting possible▫ Hemophilia—genetic disorder in the blood clotting

pathway.

Chapter 37: Respiratory System•Function: Basic function is to bring about

the exchange of oxygen and carbon dioxide between the blood, the air, and tissues.

•Structures: There are 3 major parts of the respiratory system: ▫The airway▫Lungs▫Muscles of respiration. 

Chapter 37: Respiratory System•The airway

▫The airway includes the nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles

•Pharynx—serves as a passageway for both air and food.

•Larynx—contains two highly elastic folds of tissue known as the vocal cords.

•Trachea—windpipe •Bronchi—two large passageways that lead

from the trachea to the lungs.

Chapter 37: Respiratory System•The lungs are a pair of spongy, air-filled

organs located on either side of the chest•There are 150 million alveoli in each

healthy lung.•Oxygen dissolves in the moisture on the

inner surface of the alveoli and then diffuses across the thin-walled capillaries into the blood.

•Carbon dioxide diffuses in the opposite direction.

Chapter 37: Respiratory System• Muscles of Respiration• Diaphragm—large, flat muscle

located at the bottom of the chest cavity.

• When you breathe in, or inhale, the diaphragm contracts and the rib cage rises up.▫Creates a partial vacuum.▫Atmospheric pressure then fills the

lungs with air.• Exhaling is passive. The rib cage lowers and the

diaphragm muscle relaxes and the pressure in the chest cavity becomes greater than atmospheric pressure

Chapter 38: Digestive System

•Function: The digestive system is a group of organs working together to convert food into energy and basic nutrients to feed the entire body

•Structures: ▫Mouth, pharynx,

esophagus, stomach, liver, small intestine, and large intestine

Chapter 38: Digestive System

•Mouth▫Chewing begins the process

of mechanical digestion—the physical breakdown of large pieces into smaller pieces.

▫Saliva—contains amylase, an enzyme that breaks the chemical bonds in starches and releases sugars.

•Esophagus ▫Food tube—carries food from the mouth to

the stomach

Chapter 38: Digestive System

•Stomach—large muscular sac that continues the mechanical and chemical digestion of food.▫Chemical digestion—pepsin (an enzyme) and

hydrochloric acid begins the process of protein digestion

▫Mechanical digestion—muscles contract to churn and mix stomach fluids and food producing a mixture known as chyme.

•Liver—produces bile which assists in breaking down fats

Chapter 38: Digestive System

•Small intestine—location of most of the chemical digestion and absorption of the food you eat

•The folded surface of the small intestine is covered with fingerlike projections called villi.▫Each villi is covered by thousands of

fingerlike projections called microvilli.

▫Provide and enormous surface area for absorption.

•Large intestine—function is to remove water from the undigested material that is left.

Chapter 38: Excretory System

•Function: The excretory system maintains the homeostasis of several important internal conditions by controlling the excretion of substances out of the body. 

•Structures:▫Kidneys ▫Bladder

Chapter 38: Excretory System

• Kidneys—remove waste products from the blood; maintain blood pH; and regulate the water content of the blood, and therefore, blood volume.

• Located on either side of the spinal column near the lower back.

• Activity of kidneys is controlled by the composition of blood itself.

• Bladder—saclike organ where urine is stored before being excreted

Chapter 38: Excretory System

•If anything goes wrong with the kidneys, serious medical problems follow.

•Transplant of a healthy kidney from a compatible donor.

•Kidney dialysis—blood is removed from the body through a tube and pumped through special tubing that removes waste products.▫The purified blood is then

returned to the body.