College BiologyHuman Body SystemsChapters 35-40

Organization in Multi-cellular Organisms

1. Cell

2. Tissue – group of similar cells that perform a particular function

3. Organ – group of tissues that work together

4. Organ System – group of organs that work together

5. Organism

11 Organ Systems

Feedback Control Feedback systems - control

& regulate body processes. Organ systems work together,

use feedback to maintain homeostasis

Homeostasis = stable internal conditions

Uses the consequences of the process (too much or too little produced) to control the rate at which the process occurs

Consists of a sensor, a control center, and an effector

Feedback Control Example:

Body Temperature

Digestive System

Structures: mouth, pharynx, esophagus, stomach, small intestine, large intestine

Accessory Structures: salivary glands, pancreas, liver, gallbladder

Functions: Acquiring nutrients: Breaks down

large food molecules into simpler molecules that can be used by the cells of the body

Absorbs nutrients and eliminates waste

Pathway of Food

Mouth: Chewing mechanically (physically) breaks down foodSalivary Glands: Saliva contains enzymes that break down starch

(carbohydrate)Pharynx: Beginning of throat Connects mouth to esophagus

Esophagus: Muscle contractions

(peristalsis) push food down toward the stomach

Stomach: Churns food (mechanical

digestion) Enzymes break down

proteins Does NOT absorb any

nutrients Secretes acid

Small Intestine: Chemical digestion of carbs, proteins, and lipids

finishes Carbs, proteins, and lipids are absorbed into the blood Liver, gallbladder, and pancreas secrete enzymes into

it for chemical digestion Very long and lined with villi, “wrinkles” that increase

surface area for more absorption

Accessory OrgansFood never enters these organs!Pancreas: Secretes enzymes into small intestine to break down

nutrientsLiver: Stores extra glucose as the polysaccharide glycogen Makes bile (which breaks down fats) Filters out toxins (alcohol, drugs, bacteria, old cells) from

bloodGallbladder: Stores bile made by the liver

Large Intestine (including rectum and anus):

Absorbs water from waste and then eliminates waste as feces

Close-up of the Digestive System

Summary of Food Breakdown

Respiratory System

Structures: nose, pharynx, larynx, trachea, bronchi, bronchioles, lungs

Functions: Gas exchange

Provides oxygen needed for cellular respiration

Removes excess carbon dioxide from the bloodstream

Breathing

Inhalation: “breathing in.” Exhalation: “breathing out.”

Accomplished by expanding/contracting diaphragm muscle

Pathway of air: nose, pharynx, larynx, trachea, bronchi (lungs), bronchioles (lungs).

Tiny air sacs, alveoli, are at the end of each bronchiole, surrounded by blood capillaries.

Alveoli = site of gas exchange. Oxygen diffuses from alveoli to blood, carbon dioxide diffuses from blood to alveoli

Gas Exchange in the Lungs

Circulatory System

Structures: heart, blood vessels, blood

Functions: Transport: Brings oxygen,

nutrients, and hormones to cells

Helps fight infection Regulates body temperature

Blood Contents Plasma – fluid part of blood

that carries nutrients, enzymes, hormones, and wastes

Red blood cells – contain the iron-based protein hemoglobin, which carries oxygen Made in bone marrow

White blood cells – attack foreign substances

Platelets –help blood clot

Circulatory System: Structures

Heart - Made of muscle, pumps blood through body

Arteries – carry blood away from heart to capillaries Capillaries – tiny vessels that allow diffusion of

materials between blood and cells; where arteries and veins meet

Veins – carry blood back to heart from capillaries

Blood Flow De-oxygenated blood is

pumped from the heart to the lungs where it picks up oxygen.

Oxygenated blood flows back to the heart.

Oxygenated blood pumped out to body cells to deliver oxygen and pick up carbon dioxide.

De-oxygenated blood flows back to the heart and the cycle restarts.

Nervous System

Structures: brain, spinal cord, peripheral nerves (sensory and motor)

Function: Controls and coordinates

functions throughout the body in response to internal and external stimuli

Neurons A message called an action potential is transmitted by

nervous cells (neurons). Action potentials are electrical signals. Neurons have 3 parts:

• Dendrites – receive message (action potential) • Cell body – contains the nucleus and other normal

organelles• Axon – sends action potential message to another cell

Synapse = the space between the end of one neuron and the start of the next

Neurons transmit messages by sending chemicals (neurotransmitters) across the synapse.

Muscular System

Structures: Skeletal muscle, smooth muscle, cardiac muscle

Functions: Movement

Works with skeletal system to produce voluntary movement

Helps circulate blood and move food through the digestive system

Three Types of Muscle: Skeletal: attached to bones by tendons;

voluntary Smooth: controls digestion, breathing,

circulation; involuntary Cardiac: heart muscle; involuntary

Muscles cause movement by contracting (getting shorter) or relaxing (getting longer)

Example: When the bicep muscle (a flexor) contracts and the tricep muscle relaxes, the arm bends.

When the tricep muscle (an extensor) contracts and the bicep muscle relaxes, the arm straightens.

Voluntary Muscle Contractions

Skeletal SystemInternal body framework = skeletonStructures: bones, cartilage, ligaments, tendons

Functions: Supports the bodyProtects internal organsEnables movementStores calciumMakes blood cells

Bone Structure

Bones – cells and protein fibers supported by hard calcium

Cavities within bones contain soft bone marrow, which produces blood cells.

Joints

Joints – where bones are joined together

Tendons – connect muscle to bone

Ligaments – connect bone to bone

Cartilage – a protective cushion or covering

Integumentary System

Structures: skin and its structures (hair, nails, sweat glands, oil glands)

Functions: Serves as a barrier against infection,

injury, and UV radiation from the sun Helps to regulate body temperature

(by sweating or expanding blood vessels)

Removes waste (sweat)

Close-up of Integumentary System

Excretory System

Structures: kidneys, ureters, urinary bladder, urethra (other: skin, lungs)

Functions: Eliminates waste, especially

byproducts of metabolism Regulates (controls) the amount of

water in blood, which determines blood volume and pH

Blood enters kidneys, full of excess water and nitrogenous wastes.

Excess water & wastes filtered out by the kidneys, collected as urine.

Urine travels down the ureters, gets stored in the bladder, and is expelled from the body through the urethra.

Remember: liver also filtered blood, but it removed toxins, whereas the kidneys remove wastes & water

How do the kidneys work?

Lymphatic System

Structures: white blood cells, thymus, spleen, lymph nodes, lymph vessels

Functions: Helps protect the body from disease

Maintains fluid balance in blood

Spleen – filters old blood cells from blood, stores extra blood

Immune System: Non-specific Defenses

Function: fights off invading pathogens and prevents growth and spread of cancer

Non-specific Defenses: protect body from all pathogens. Skin: physical barrier Mucous membranes: protect

interior surfaces Cilia: line bronchi to “sweep”

mucus and pathogens out of lungs

Immune System: Specific Responses

Specific Responses: defend against one certain invader (pathogen) White blood cells recognize an

invader

Create antibodies, proteins which bind to pathogens & mark them for destruction

Endocrine System

Structures: ovaries (females), testes (males), pancreas, hypothalamus, glands (pituitary, pineal, thyroid, parathyroid, thymus, adrenal)

Function: Chemical communication &

control Hormones - chemicals that are

released into the blood and signal cells to take action Actions include growth,

development, metabolism, and reproduction

Reproductive System

Male Structures: testes, epididymis, vas deferens, urethra, penis

Female Structures: ovaries, fallopian tubes, uterus, vagina

Functions: Produces reproductive cells Males: produce and deliver

gametes (sperm) to females Females: produce gametes

(eggs), maintain an environment which can support a developing embryo