Human Body Systems

Evolution of Digestion Systems

Phagocytosis and digestion within a food vacuole

Gastrovascular cavity- two way flow!

Complete digestive system- one way flow!

Human Digestive SystemThe digestive system is responsible for breaking down and converting food into a usable form.

Mouth

• Beginning of the digestive system

• Chewing breaks food into pieces that are easier to digest

• Carbohydrates are digested by maltose into disaccharides

Pharynx• Receives food after it’s

swallowed • Passageway for food and air• Epiglottis- opens and closes

trachea• Average: 5 inches long

Esophagus

• “Channel” that food travels from the mouth to the rest of the digestive system

• Peristalsis – Muscular contractions that move food down

Stomach

• “Container” that stores food and breaks down protein with pepsin into small polypeptides. Hydrochloric acid activates pepsinogen into pepsin in a positive feedback

Small Intestine

• Duodenum – Mixes enzymes produced by the pancreas and liver to break down food

• Jejunum and Ileum - Absorb nutrients into the bloodstream with millions of villi that increase surface area for absorption.

• Average: 22 -25feet long

Large Intestine• Also called the “colon”• Average: 6 feet long • Divided into Ascending

(right) colon, Transverse (across) colon, and Descending (left) colon

• Responsible for processing waste to be removed from the body and absorbing water

• Bacteria make vitamin K for us in a mutualistic symbiotic relationship

Rectum

• Connects large intestine to the anus

• Holds stool until released• Average: 8 inches long

Anus• Final part of digestive

system• Internal and External Anal

Sphincters• Releases stool• Average: 2 inches long

Salivary Glands

• First part of chemical digestion• Produces saliva to help form the bolus (“ball” of chewed food)

and begin digestion of food

Liver

• Main function is to process nutrients absorbed by the small intestine

• Produces certain blood plasma proteins

• Detoxifies alcohol and ammonia• Breaks down drugs• Process hemoglobin and stores

iron• Produces bile which emulsifies

fats and neutralizes stomach chyme

• Regulates blood clotting

Pancreas• Produces enzymes that break down proteins,

carbohydrates, and fats• Secretes insulin and glucagon• Produces chemicals that help neutralize stomach acids• Average: 6 inches long

Pancreas

Gallbladder

• Stores and releases bile into the duodenum to emulsify fats

Sphincters

• Controls the release of food from one organ to another

• Includes: Pyloric Sphincter, Cardiac Sphincter, Urethral Sphincter, Cervix, and the Internal and External Anal Sphincters

Cardiac Sphincter

Pyloric Sphincter

Accessory Organs

Salivary Glands

Liver

Gallbladder

Pancreas

Organs Food Passes Through

Mouth

Pharynx

Esophagus

Stomach

Small Intestine

Large Intestine

Rectum

Anus

Digestion of Large Molecules

• Food must first be broken down into smaller pieces to increase surface area for enzyme action

• Large food molecules have to be broken down into building blocks to be able to be absorbed into the blood or lymph

• Food is broken down and “rearranged” into a form that humans can use – The parts we can’t use are egested as waste

• Enzymes play a crucial role in the digestion of large food molecules

• Only food small enough to be absorbed by the villi of the small intestine is used as nutrition by the human body

Chemical Digestion

• Chemical digestion of food through enzymes

• Necessary to further digest food into building blocks for absorption

• Occurs in the mouth, stomach and small intestine

Physical Digestion

• Physical, mechanical digestion of food through chewing, churning or acids and bile

• Substances stay the same, just smaller pieces

• Occurs in the mouth, stomach and small intestine

Role of Enzymes

• Enzymes dramatically increase the rate at which food is broken down. Such as…

• Amylase breaks down carbohydrates• Protease breaks down proteins• Lipase breaks down fats (lipids)

Digestion of Carbohydrates, Proteins, and Lipids

Hormones that Regulate Digestion

Ulcers

• A weakening in the lining of the stomach or small intestine.

• Pain in the abdominal region is caused by stomach acid eroding nerve endings.

• Up to 10% of Americans will develop ulcers sometime in their lives.

• Treatment is with antacids and/or antibiotics if caused by bacteria.

How Does this System Relate to others?

• Muscular – contains smooth muscle• Nervous – gets signals that control

the rate of digestion• Circulatory – broken down food

travels through blood vessels to cells• Endocrine – hormones (ex. Insulin)

control blood sugar levels

Circulatory System

• Consists of blood, the heart, and blood vessels

• The Circulatory System transports materials (including gas, nutrients, wastes, and hormones), contains cells that fight infection, stabilize ionic concentration and pH of fluids the body, and transports heat to maintain temperature.

Structure and function of blood vessels• Arteries carry blood away from the heart to the rest of the body under

enormous pressure• Capillaries allows for diffusion of nutrients and wastes between cells and

blood. Connect arteries and veins• Veins return blood back to the heart under very little pressure

Route of Blood• Left ventricle, aortic valve, aorta, peripheral arteries,

arterioles, capillaries, venules, peripheral veins, vena cava, right atrium, tricuspid valve, right ventricle, pulmonary valve, pulmonary artery, pulmonary capillaries, pulmonary veins, left atrium, mitral valve, and left ventricle.

• Blood valves ensure the flow of blood goes the intended (one-way) direction. (Ex. Of bulk flow!)

• Tricuspid valve allows flow into the Right Ventricle from the Right Atrium

• Mitral valve allows flow into the Left Ventricle from the Left Atrium

• Aortic valve allows flow into the Aorta from the Left Ventricle• Pulmonary valve allows flow into the Pulmonary Artery from

the Right Ventricle

Blood Composition Blood is a liquid tissue that is made of plasma, erythrocytes,

leukocytes, and platelets. Plasma is the straw-colored liquid that contains the cells. Erythrocytes, or red blood cells, make up ninety-nine

percent of the cells in blood. Two types of protein (A and B) are found there and different combinations make up the four blood types (A, B, AB, O)

Leukocytes, or white blood cells, are a large source of defense for blood and “clean” it by picking up dead cells. These cells can be used to diagnosis sicknesses.

Platelets are used when damage takes place on the body. They trap the open wound and clot together to form a scab to prevent dangerous loss of blood

Erythrocytes Erythrocytes are flat and

cylindrical, which allows more oxygen and carbon dioxide to be carried throughout the body. They are also very flexible and move efficiently through veins and vessels. They are made of hemoglobin which is composed of iron and proteins.

They demonstrate how structure influences function because the shape of the cell includes “indents” that allow it to carry and transport oxygen molecules

Open and closed circulatory systems

• All vertebrates, and a few invertebrates, have closed circulatory systems – Example: Humans

• Most invertebrates have open circulatory systems – Example: crabs

• Closed: Blood is closed at all times within blood vessels and pumped by the heart through vessels not filling body cavities

• Open: Blood is pumped by the heart into body cavities where tissues are surrounded by blood

Fish circulatory system• Fish have single circulation

where blood passes through the heart once in a complete circuit. Contraction of the ventricle pumps blood to the gills where there is a net diffusion of oxygen into the blood and carbon dioxide out of the blood. When blood leaves the gills, capillaries converge into a vessel that carries oxygen right blood to capillary beds through the body, then blood returns to the heart.

Amphibian circulatory system

• 3-chambered heart with two atria and one ventricle

• Blood moves from the heart to the pulmonary capillaries where gas is exchanged and then returned to the heart

• Some of the blood returned to the heart goes to the pulmonary circuit, some to the systemic circuit

• Mixes oxygen-rich and oxygen-depleted blood

Reptile circulatory system

• 3-chambered heart• One ventricle, two aortas• Some have partial separation

of systemic and pulmonary circuits, others complete separation

• Variations in blood flow allow deoxygenated blood to be returned to the body or oxygenated blood to be returned to the lungs, if needed

Mammal circulatory system

• 4-chambered heart• Two atriums, two ventricles• Separation of systemic and

pulmonary circuits• Mammalian red blood cells

lack a nucleus to maximize oxygen transport

Bird circulatory system

• 4-chambered heart• Separation of systemic and pulmonary circuits• Arranged for optimal blood transport – Birds have hearts that

are proportionally 3 times larger than mammals and beat 5 to 6 times as fast

Atherosclerosis

• Atherosclerosis is the hardening of the arterial wall due to the build up of plaque.

• Symptoms include decreased or stopped blood flow and sharp pain. Sometimes the first sign is a heart attack.

• About 11.5% of the population has some coronary artery disease

• Treatment: Statins drugs to lower cholesterol reduce build-up of plaque

Hypertension

• Commonly known as high blood pressure

• Most people show no signs, though headaches and dizziness may be a result

• High blood pressure increases the chances for heart attacks

• The incidence in US adults is about 30%

• Treatment: Exercise and a diet low in sodium and fats reduce the risk of heart disease

How Does this System Relate to others?

Connected to almost all other systems since the circulatory system carries oxygen to all cells

Respiratory System

The function of the Respiratory System is to take in oxygen by inhalation and take the oxygen to the cells throughout the body, while carbon dioxide is taken out through exhalation. Besides respiration, the respiratory system also aids in coughing and vocals.

Alveoli• Alveoli are the places where

gases are exchanged. Oxygen diffuses into the blood and carbon dioxide diffuses into the alveolar air space.

• The total surface area they provide is about 100 square meters.

• Alveolar tissue is made of elastic fibers and allows the alveoli to stretch and compress.

• Capillaries cover 70% of the area and gases readily diffuse through the thin fluid lined membranes.

Carbon Dioxide and Oxygen

• Some oxygen is carries to body cells dissolved in plasma, but most is carried by red blood cells. Red blood cells contain hemoglobin which binds to oxygen molecules.

• One red blood cell can carry four oxygen molecules at a time. • Path of oxygen: Air > mouth/nose > pharynx > larynx >

trachea > lung > bronchi > bronchioles > alveoli > pulmonary capillaries > hemoglobin< body cells

• Carbon dioxide is transported in blood by a few processes. It diffuses along the concentration gradient into the plasma through the tissues. When it is in the blood it enters the hemoglobin and becomes bicarbonate, some stays in the plasma.

Inhalation and Exhalation• Inhalation is the process of

taking air into the lungs. The diaphragm contracts to expand the thoracic cavity and increase the volume. This causes the air pressure inside the lungs to be lower than the air pressure outside, so air moves into the body.

• Exhalation is the process of expelling air from the lungs. The diaphragm relaxes and decreases the volume of the thoracic cavity. The air pressure inside the lungs is now greater than that of the outside of the lungs, and air leaves the body.

Asthma

• Bronchial airways are too narrow

• Coughing, wheezing, and difficulty breathing

• For adults, the incidence of asthma is about 16%

• Treatment: Bronchodilators relax airway passages

Disorders Asthma: inflammatory disorder of the

airways where the muscles become tight and air passages swell. Symptoms include wheezing, shortness of breath, and coughing. Approximately 1 in 15 Americans suffer from asthma. Treatment includes inhalant corticosteroids and inhibitors.

Pneumonia: is an infection in the lungs where bacteria or viruses infect. Symptoms include coughing, shaking, chills, and shortness of breath. About 4.8 million people in America have had pneumonia. This can be treated by amoxicillin, Avelox, or other antibiotics.

Tuberculosis

• Tuberculosis is an infectious disease caused by the bacteria Mycobacterium tuberculosis

• The bacteria causes lesions to form on the lymph nodes

• Prevalence in the United States is about 3.6 cases per 100,000 individuals, though the incidence rate is far higher for areas of Africa and Asia

• Treatment: Combinations of antibiotics are usually successful in curing the disease

How Does this System Relate to others?

•Circulatory – brings O2 to the cells and CO2 back to the lungs• Excretory – part of the

excretory system to get rid of toxic CO2 from the body

Muscular System

The function of the muscular system is to allow movement, maintain posture, and circulate blood throughout the body.

The Three Types of Muscle Tissue

• Skeletal muscle occurs in muscles attached to the skeleton that allow for movement

• Cardiac muscle is in the heart and under involuntary control as it pumps blood

• Smooth muscle forms the walls of hollow organs and is also under involuntary control

Skeletal Muscle Contraction

The sliding filament theory involves bind-and-release impulses that cause myosin to move along the filament and forcing thick filament to move over thin filament. After an impulse is sent from the brain, calcium channels in the muscular axon open and calcium ions move in to cause the release of acetylcholine. Acetylcholine acts as a transmitter that attaches itself to receptors in the sarcomere. This triggers an action potential that causes the release of calcium ions from the sarcoplasmic reticulum. These ions trigger actin sites and the ions begin binding to troponin. Tropomyosin is released and then blocks the binding of actin which causes the muscle to contract. The troponin that is formed prevents some of the blocking action of tropomyosin and some myosin heads attach to active actin sites. These myosin heads form cross bridges using ATP. The ATP is broken into ADP and phosphates which cause the myosin to detach from the actin sites and hydrolyze ATP. This recharges the myosin to repeat the process. This bind-and-release action causes muscle contraction.

Muscular Dystrophy

• Muscular dystrophy is a series of more than 30 genetic diseases that cause the degeneration of skeletal muscles that control movement

• Primarily affecting males, by the age of 12 victims usually cannot walk and need respirators to continue breathing

• The disease is very rare; females carrying the gene have a 50% chance of passing it to their children

• There is no treatment to stop or reverse muscular dystrophy – There is only physical and speech therapy and respiratory assistance

Myasthenia gravis

• An autoimmune neuromuscular disease, the immune system produces antibodies that block muscle cells from receiving signals from nerve cells

• Myasthenia gravis causes severe weakness of voluntary muscles and can result in trouble breathing and walking

• Incidence is about 1 in 500,000• Very little is known about the

disease. Current treatment is lifestyle changes such as rest and avoiding stress and heat.

How Does this System Relate to others?

• Works closely with the:–skeletal system–Circulatory – brings O2 to

muscles and waste products such as lactic acid away–Nervous – how muscles contract

Skeletal SystemThe skeletal system has six major functions:• Support• Protection• Aiding in Movement• Storage of Minerals• Production of Red Blood

Cells• Chemical energy storage

Human Movement

• Bones fit together at joints, which allow pivotal movement• Ligaments connect bones together and can stretch to allow

movement• Muscles move bones by extending or flexing a joint• Tendons attach muscles to bones

Hydrostatic Skeleton

• Hydrostatic skeletons consist of fluid under pressure

• This type of skeleton is common among worms and higher invertebrates such as hydras, planarians, and segmented worms

Exoskeleton

• Most aquatic animals and some terrestrial animals (insects) have rigid skeletons on the outside of their body

• Usually made from chitin• Animal must shed its

skeleton and form a new one when it outgrows its old one

• Example: Beetles

Endoskeleton

• Animal skeletons are endoskeletons

• Consists of bone and cartilage made from calcium and grows with the animal

• Vertebrates have this skeleton, but some invertebrates such as sponges, sea stars, and sea urchins have endoskeleton plates underneath their skin

Osteoporosis

• Osteoporosis is the most common skeletal disease

• Bones become weaker from a lack of calcium and break easily

• 1 in 5 women over the age of 50 develop the disease

• Treatments include medication, pain therapy, and lifestyle changes that prevent the risk of falls

Arthritis

• Arthritis is the inflammation of one or more joints – There are over 100 different types

• Symptoms include joint pain, swelling, reduced ability to move a joint, and stiffness.

• Many Americans face arthritis at some point in their lives, especially the elderly

• Treatments include pain therapy, physical therapy, pain medication, and lifestyle changes.

How Does this System Relate to others?

• Works closely with the:–Muscular system for movement

system–Circulatory – bones make blood–Nervous – Provides a storage of

calcium used for nerve impulses and muscle contractions

Senses System

The function of the senses system is to give the body the ability to detect the outside world.

Sensory Receptors

• Mechanoreceptors detect changes in pressure, position, and acceleration (nose, skin, ear)

• Thermoreceptors detect hot or cold temperatures (skin)

• Chemoreceptors detect ions and molecules (nose)

• Photoreceptors detect light (eyes)• Pain receptors detect severe heat, pressure, and

chemicals that harm the body (skin)

Reproductive System

• The function of the reproductive system is to continue the survival of the species. It is the means by which the body can transfer genes from one individual to another.

Sexual Reproduction vs. Asexual Reproduction

• Both are ways for organisms to procreate their species.

• Sexual reproduction involves two organisms while asexual involves one

• Sexual reproduction produces diversity; asexual reproduction creates “clones”

• Hydras, sponges, and planarians are animals that exhibit asexual reproduction

Spermatogenesis• Spermatogenesis occurs in the seminiferous tubules of the testes in males• Primary spermatocytes undergo meiosis to form secondary spermatocytes,

which also undergo meiosis to form 4 haploid spermatids• These spermatids undergo a stage of metamorphosis to become mature

spermatozoa

Oogenesis• Oogenesis occurs in the ovaries in females• Oogenesis begins with a immature primary oocyte that divides into a secondary oocyte

and a smaller first polar body• The secondary oocyte produces a mature ovum and a small polar body while the first

polar body creates two more smaller polar bodies• Oogenesis creates one mature egg cell and three small polar bodies that go on to die• These three polar bodies “donate” their cytoplasm and nutrients to the mature egg cell

Menstrual cycle vs. Estrous cycle

• Humans and the great apes follow the menstrual cycle, while the rest of the animal kingdom (the female half) undergoes the estrous cycle

• Animals with the estrous cycle reabsorb the endometrium if conception doesn’t occur, while animals with the menstrual cycle shed the endometrium through menstruation

• Animals with the estrous cycle are sexually active only during the estrous phase of the cycle, while animals with the menstrual cycle are sexually active at any time of the cycle

Menstrual cycle

• The menstrual cycle usually occurs over 28 days. • The cycle starts with menstruation (the uterine cycle) where the

endometrium is shed as the egg isn’t fertilized and the body prepares the way for a new egg

• The follicular phase (the ovarian cycle) comes after as a follicle stimulating hormone (FSH) stimulates the lining of the uterus to grow. These follicles also secrete estrogen and initiate the formation of a new endometrium.

• The luteal phase (part of the ovarian cycle) occurs when the ovaries form the corpus luteum and release progesterone which readies the uterus for the implantation of the blastocyst.

• If there is no fertilization, menstruation occurs again and the egg is lost.

• The menstrual cycle is a feedback mechanism that is regulated by the presence of fertilization and the quantity of certain hormones.

Feedback Mechanisms• Positive feedback mechanisms in the menstrual cycle

occurs during the follicular phase when estrogen released from the follicle stimulates the release of LH from the anterior pituitary. The increase in LH stimulates the follicle to release even more estrogen. The hormone level continues to rise until the follicle matures and ovulation occurs.

• Negative feedback mechanisms in the menstrual cycle occur during the luteal phase when LH stimulates the corpus luteum to secrete estrogen and progesterone. Once the levels of estrogen and progesterone reach sufficiently high levels, they trigger the hypothalamus and pituitary to shut off, thereby inhibiting the secretion of LH and FSH

Development

• The fertilized ovum forms a “ball of cells” called a morula through the process of cleavage, where the zygote undergoes rapid cell division

• This ball eventually expands and becomes hollow, called a blastula

• Gastrulation comes after and divides the body into three layers as outside ectoderm cells move inward to form the endoderm. This final three-layer ball is called the gastrula.

• Organogenesis is the final stage in early development as cells in each layer differentiate and form the organs of the human body

Germ Layers

• Ectoderm is the outermost layer and forms the skin, nails, hair, sweat glands, facial muscles, and the brain and the spinal cord.

• The mesoderm is the middle layer and forms the heart, kidneys, bones, muscles, and blood vessels.

• Endoderm is the innermost layer and gives rise to the respiratory and digestive systems.

Factors That Influence Embryonic Development

• When an eight ball sea urchin embryo is separated into 2 halves, the future development of the 2 halves depends on the plane in which they are cut. If the dissection is longitudinal, producing embryos containing both animal and vegetal cells, the subsequent development id normal. But if the plane of the dissection is horizontal, the result is abnormal development. This demonstrates that the cytoplasm surrounding the nucleus has profound effects on embryonic development. The importance of the cytoplasm in the development of the embryo is known as cytoplasmic determinants.

2 normal adultsAbnormal

development

Factors That Influence Embryonic Development

• The Gray Crescent- Hans Spemann demonstrated the importance of the cytoplasm associated with the gray crescent in the normal development of an animal. He dissected embryos at the 2 cell stage and only the cell containing the gray crescent developed normally.

Factors That Influence Embryonic Development• Spemann also proved that the

dorsal lip of a the blastopore which normally initiates a chain of inductions that result in the formation of a neural tube, could be transplanted and induce any tissue to become neural tissue. Spemann called the dorsal lip the primary embryonic organizer. Scientists have now identified the protein ß-catenin as the likely candidate for the transcription factor that triggers which cells become the “organizers”

Gonorrhea

• Gonorrhea is a sexually transmitted disease that causes severe pain and infertility

• Symptoms include swollen reproductive tracts, pain when urinating, and fevers

• Gonorrhea is the most common STD, but the incidence is less than 1% of the general population

• Treatments include antibiotics and pain medications

Syphilis

• Syphilis is a sexually transmitted disease that can cause infertility and death

• Symptoms include sores where syphilis entered the body, rashes, mucous discharge, fatigue, and finally damage to the heart, eyes, nerves, and brain.

• The incidence rate in the US among males 5.7 percent

• Treatments include antibiotics

How Does this System Relate to others?

The reproductive system works most closely with the endocrine system (hormones)