Respiratory System

The respiratory system helps to breathe – which is inhaling oxygen so that it can be distributed to each cell in the body and collect the waste product carbon dioxide from the cells and expel it back to the atmosphere.

The human respiratory system consists of:

The nasal passages

Pharynx

Larynx

Windpipe

Lungs

The exchange of the gases – replenishing the blood with oxygen and removing carbon dioxide from it – happens in the lungs. We breathe about 6 liters of air every minute. The adult lungs have the capacity to hold about 3 liters of air.

When we breathe, the air first enters the body through the nose or the mouth and enters the trachea. The trachea splits into two bronchi – one going to each lung. Each bronchus continues to divide into narrower and narrower bronchi ending up as microscopic alveoli. The walls of alveoli are single celled through which the blood can exchanges the carbon dioxide with oxygen from the fresh air in the lungs.

What makes us breathe?

The breathing action is as a matter of fact is not initiated by the lungs. They are like bags which get compressed and expanded due to a dome shaped muscle that attaches to both the lungs. This muscle is called the diaphragm. The diaphragm is an involuntary muscle that keeps contracting and flattening. When the diaphragm contracts, it pushes the ribs upward and out. This makes the lungs expand. When the lungs expand, the pressure in the lungs in less than the atmospheric pressure, due to which the air from the outside rushes in. This action of pulling in the outside air into the lungs through the nose and or mouth is called the inhaling.

When the diaphragm returns to its normal shape, the ribs move downward and in thereby squeezing the lungs which therefore force the air out of the body. This is called exhaling.

What are the diseases of the respiratory system found in humans?

The common diseases that affect the respiratory system are:

Bronchitis

Pneumonia

Asthma

Lung Cancer

Emphysema

As obvious, any infection or disease associated with the respiratory system makes breathing difficult. When the body is not able to get sufficient oxygen, the heart tries to work faster to circulate more blood so that enough oxygen can be supplied to the parts of the body. The lack of oxygen due to difficulty in breathing can make the body feel tired. A severe lack of oxygen can also prove to be fatal.

How can we keep the respiratory system healthy?

The respiratory system can keep healthy if we breathe fresh air. Inflammation of the bronchi or the lungs may not be easy to prevent but trying to keep away from infections or infected people can help you stay healthy. The tumors in the may not be preventable.

However, smoking is one major activity that is extremely harmful and that many adults and youth indulge in.

Skeletal System

Skeletal System

Skeletal system is the biological system providing support in living organisms.

Skin, muscle and bones allow movement. Skin - pliable covering. Muscles do actual moving. Bones give anchor to move against.

The skeleton functions not only as the support for the body but also in haematopoiesis, the manufacture of blood cells that takes place in bone marrow. This is why people who have cancer of the bone marrow almost always die. It is also necessary for protection of vital organs and is needed by the muscles for movement.

Introduction To Skeletal System

Bones

A. Functions of Bones

1. Support. Provide a hard framework.

2. Protection of many vital organs.

3. Movement. Act as levers with skeletal muscles moving them. Joints control possible movements.

4. Mineral storage. Especially calcium and phosphate, critical minerals for cellular function. Continuous deposition and withdrawal. Exquisite control of Ca++ (calcium ions) levels necessary for function of nerves, muscles, blood coagulation and other functions. Most of Ca++ in body in bones. Osteoclasts & osteoblasts controlled by hormones which regulate blood levels of Ca++.

5. Blood cell formation. Certain bones have active marrow.

B. Structure

1. Compact-Dense outer layer, looks smooth and solid. Contains cylinder of concentric layers with central canals.
a. Haversian system = circles of bone (lamella) with central canal (Haversian canal)
b. Central canal contain blood vessels & nerves. Connected at right angles to network.
c. Perforating small canals - blood vessels & nerves go through lamellar bone to supply osteocytes. Connect to periosteum.
d. Osteocytes live in bone, maintain it. Live in holes called lacunae. Connect to each other and central canal via canaliculi, little canals. Pass nutrients, waste products

2. Spongy- honeycombed, open spaces. Same structure as compact but less regular.

Withstand maximum stress with least weight. In bone interiors & weird weight bearing bones like head of femur. Not organized in lamella. Trabeculae are arranged along lines of stress. Osteocytes interconnected by canaliculi. Nutrients reach osteocytes by diffusing through the canaliculi from capillaries. Osteoporosis - More bone resorption than deposition, very weak bone.

Skeletal System

A. Axial skeleton

Principal supportive structure of the body includes skull, vertebrae, sternum & ribs. Central column of the skeleton from which arms and legs & bones that help them hang.

B. Appendicular skeleton

Provides fairly freely movable frame for upper & lower limbs. Includes pectoral (shoulder) & pelvic (hip) girdles, arms, forearms, wrists, hands, thighs, legs & feet.

Joints

Bones -> framework; muscles -> power; joints provide mechanism that allows body to move

A joint is where 2 adjacent bones or cartilages or combination thereof meet.

Most joints movable, some not.

General Structure

1. Articular cartilage

2. Joint (synovial) cavity

3. Articular capsule - external layer = fibrous capsule, inner layer is a synovial membrane

4. Synovial fluid-occupies all free spaces within the joint capsule, fluid derived by filtration from blood flowing thorough the capillaries in the synovial membrane

5. Reinforcing ligaments

Divisions of the sceletal system

The skeleton is divided into the axial skeleton and the appendicular skeleton. The axial skeleton includes the bones of the skull, the hyoid bone, the bones of the middle ear, the vertebral column, and the bony thorax.
The appendicular skeleton includes the bones of the extremities and the bones of the hip and shoulder girdles.
• Axial skeleton •
• Facial bones •
• Vertebral column •
• Curvatures •

RESPIRATORY SYSTEM

The respiratory system main task is to supply oxygen to the blood and getting rid of waste gases. Carbon dioxide is the primary gas that the blood gets rid of. The upper structures of the respiratory system are combined with the sensory organs of smell and taste and the digestive system. When you inhale (breathing in) your skeletal muscle and the diaphragm contract, which then enlarge the chest cavity and cause the lungs to draw in air. This creates a partial vacuum in the thoracic cavity, air passes through the nose, pharynx, larynx, trachea, and then into the two bronchi to the lungs. Oxygen and carbon dioxide pass between the blood and the air in the alveoli, which are at the end of the smallest bronchi. Oxygen diffuses from the inhaled air through the alveoli walls into the capillaries. The lungs contain more than 300 million alveoli. When you exhale or breathe out, your skeletal muscles and diaphragm return to the relax position which decrease the size of the chest cavity and therefore pushes the air out of the lungs. The rib cage serves as a structural support for the whole thoracic arrangement, and peural membranes help provide lubrication for the respiratory organs so that they are not chaffed during respiration. The air we exhale contains 100 times more carbon dioxide than inhaled air. In a resting position a healthy individual will inhale and exhale approximately 16 time per minute.

LUNGS

LUNGS


The lungs are a pair of organs located in the chest that performs respiration. Humans have 


two lungs; the left lung is divided into two lobes and the right lung is divided into three. The 


lungs are located in the chest cavity inside the rib cage. They are made of elastic, spongy 


tissue as they stretch out and constricts while you breathe.

The trachea and the bronchi are the airways that bring the air to the lungs. They are made of


 smooth muscleand cartilage, which allows the airways to constrict and expand. The duty of


 the lungs and the airways is to bring in fresh air, rich in oxygen and as well as to get rid of


 carbon dioxide waste made by the cells. They also regulate the concentration of hydrogen


 ions in the blood.


The diaphragm and the intercostal muscles, which are the muscles located between the ribs,


contract and expand the chest cavity as you inhale. The pressure in the chest cavity below 


the outside pressure is lowered because of the expansion. Air flows into the airways and


 inflates the lungs. On the other hand, the diaphragm and intercostal muscles relax and the 


chest cavity gets smaller when you exhale. The decrease in the volume of the cavity increases


 the pressure in the chest cavity, air from the lungs then travels out of the airways. This cycle


 is repeated every time you breathe.


The air you breathe goes into the trachea and travels down to the vocal cords in the larynx up


 to the bronchi. From the bronchi, the air then passes through each lung until it reaches the


 alveoli. The oxygen concentration in each air sac is high; this causes the oxygen to pass across


 the alveolar membrane into the pulmonary capillary. The oxygen then binds to the


 haemoglobin at the beginning of the pulmonary capillary and carbon dioxide is released. 


Carbon dioxide concentration is high in the pulmonary capillary so carbon dioxide leaves the


 blood by passing through the alveolar membrane into the air sac. These processes happen in


 fractions of a second. When the carbon dioxide leaves the alveolus, the oxygen enriched-


blood goes back to the heart.


There are a number of health conditions that affect the lungs. These conditions may be


 divided into two categories: conditions that make it hard to breathe and conditions that


 damage the ability of the lungs to exchange carbon dioxide for oxygen. Some of the most


 common health conditions that make it hard to breathe are: Asthma, Bronchitis,


 Emphysema, Apnea and Pneumothorax.


The most common health conditions that minimize and prevent gas exchange are: Pulmonary


 Edema, carbon monoxide poisoning and smoke inhalation.


The peak of your lung function is in the late teens and early twenties. In your late twenties,


 lung function can decline up to about 1 percent every year. If you are a regular smoker, it can


 decline up to 2 percent every year. People who have been smoking since their teens should 


consider stopping at around their late twenties or early thirties at the risk of getting lung 


cancer. Though not all people who smoke acquire lung cancer, they are still the most at risk.

Lungs

Ear Anatomy

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BRAIN

The anatomy of the brain is complex due its intricate structure and function. This amazing organ acts as a control center by receiving, interpreting, and directing sensory information throughout the body. There are three major divisions of the brain. They are the forebrain, the midbrain, and the hindbrain.

Anatomy of the Brain: Brain Divisions

The forebrain is responsible for a variety of functions including receiving and processing sensory information, thinking, perceiving, producing and understanding language, and controlling motor function. There are two major divisions of forebrain: the diencephalon and the telencephalon. The diencephalon contains structures such as the thalamus and hypothalamus which are responsible for such functions as motor control, relaying sensory information, and controlling autonomic functions. The telencephalon contains the largest part of the brain, the cerebrum. Most of the actual information processing in the brain takes place in the cerebral cortex.

The midbrain and the hindbrain together make up the brainstem. The midbrain is the portion of the brainstem that connects the hindbrain and the forebrain. This region of the brain is involved in auditory and visual responses as well as motor function.

The hindbrain extends from the spinal cord and is composed of the metencephalon andmyelencephalon. The metencephalon contains structures such as the pons and cerebellum. These regions assists in maintaining balance and equilibrium, movement coordination, and the conduction of sensory information. The myelencephalon is composed of the medulla oblongata which is responsible for controlling such autonomic functions as breathing, heart rate, and digestion. 

• Prosencephalon - Forebrain 
  • Diencephalon 
  • Telencephalon
• Mesencephalon - Midbrain
  
• Rhombencephalon - Hindbrain
  • Metencephalon 
  • Myelencephalon 

Anatomy of the Brain: Structures

The brain contains various structures that have a multitude of functions. Below is a list of major structures of the brain and some of their functions.

Basal Ganglia

• Involved in cognition and voluntary movement
• Diseases related to damages of this area are Parkinson's and Huntington's

Brainstem

• Relays information between the peripheral nerves and spinal cord to the upper parts of the brain
• Consists of the midbrain, medulla oblongata, and the pons

Broca's Area

• Speech production
• Understanding language

Central Sulcus (Fissure of Rolando)

• Deep grove that separates the parietal and frontal lobes

Cerebellum

• Controls movement coordination
• Maintains balance and equilibrium

Cerebral Cortex

• Outer portion (1.5mm to 5mm) of the cerebrum
• Receives and processes sensory information
• Divided into cerebral cortex lobes

Cerebral Cortex Lobes

• Frontal Lobes -involved with decision-making, problem solving, and planning
  
• Occipital Lobes-involved with vision and color recognition
  
• Parietal Lobes - receives and processes sensory information
  
• Temporal Lobes - involved with emotional responses, memory, and speech

Cerebrum

• Largest portion of the brain
• Consists of folded bulges called gyri that create deep furrows

Corpus Callosum

• Thick band of fibers that connects the left and right brain hemispheres

Cranial Nerves

• Twelve pairs of nerves that originate in the brain, exit the skull, and lead to the head, neck and torso

Fissure of Sylvius (Lateral Sulcus)

• Deep grove that separates the parietal and temporal lobes

Limbic System Structures

• Amygdala - involved in emotional responses, hormonal secretions, and memory
  
• Cingulate Gyrus - a fold in the brain involved with sensory input concerning emotions and the regulation of aggressive behavior
  
• Fornix - an arching, fibrous band of nerve fibers that connect the hippocampus to the hypothalamus
  
• Hippocampus - sends memories out to the appropriate part of the cerebral hemisphere for long-term storage and retrievs them when necessary
  
• Hypothalamus - directs a multitude of important functions such as body temperature, hunger, and homeostasis
  
• Olfactory Cortex - receives sensory information from the olfactory bulb and is involved in the identification of odors
  
• Thalamus - mass of grey matter cells that relay sensory signals to and from the spinal cord and the cerebrum

Medulla Oblongata

• Lower part of the brainstem that helps to control autonomic functions

Meninges

• Membranes that cover and protect the brain and spinal cord

Olfactory Bulb

• Bulb-shaped end of the olfactory lobe
• Involved in the sense of smell

Pineal Gland

• Endocrine gland involved in biological rhythms
• Secretes the hormone melatonin

Pituitary Gland

• Endocrine gland involved in homeostasis
• Regulates other endocrine glands

Pons

• Relays sensory information between the cerebrum and cerebellum

Reticular Formation

• Nerve fibers located inside the brainstem
• Regulates awareness and sleep

Substantia Nigra

• Helps to control voluntary movement and regualtes mood

Tectum

• The dorsal region of the mesencephalon (mid brain)

Tegmentum

• The ventral region of the mesencephalon (mid brain).

Ventricular System - connecting system of internal brain cavities filled with cerebrospinal fluid

• Aqueduct of Sylvius - canal that is located between the third ventricle and the fourth ventricle
  
• Choroid Plexus - produces cerebrospinal fluid
  
• Fourth Ventricle - canal that runs between the pons, medulla oblongata, and the cerebellum
  
• Lateral Ventricle - largest of the ventricles and located in both brain hemispheres
  
• Third Ventricle - provides a pathway for cerebrospinal fluid to flow

Wernicke's Area

• Region of the brain where spoken language is understood

EYE AND EYE CONDITION

The eye is a slightly asymmetrical globe, about an inch in diameter. The front part of the eye (the part you see in the mirror) includes:

• The iris (the pigmented part)
• The cornea (a clear dome over the iris)
• The pupil (the black circular opening in the iris, which lets light in)
• The sclera (the white part)
• The conjunctiva (an invisible, clear layer of tissue covering the front of the eye, except the cornea)

Just behind the iris and pupil lies the lens, which helps to focus light on the back of the eye. Most of the eye is filled with a clear gel, called the vitreous. Light projects through the pupil and the lens to the back of the eye. The inside lining of the eye is covered by special light-sensing cells, together called the retina. The retina converts light into electrical impulses. Behind the eye, the optic nerve carries these impulses to the brain. The macula is a small sensitive area within the retina that gives central vision. It is located in the center of the retina and contains the fovea.

Eye color is created by the amount and type of pigment in the iris. Multiple genes inherited from each parent determine a person’s eye color.

Eye Conditions

• Age-related macular degeneration: A loss of central vision in both eyes.
• Myopia (nearsightedness): Inability to see clearly at a distance. The eye is “too long” for the lens, so light isn’t focused properly on the retina.
• Hyperopia (farsightedness): Inability to see near objects clearly. The eye is “too short” for the lens, or certain eye muscles have weakened with age.
• Strabismus: The eyes do not point in the same direction. The brain may then favor one eye, causing decreased vision (amblyopia) in the other eye.
• Pterygium: A thickened conjunctival mass usually on the inner part of the eyeball. It may cover a part of the cornea, causing vision problems.
• Scotoma: A blind or dark spot in the visual field.
• Amblyopia (lazy eye): One eye sees better than the other, a problem of childhood development. The weaker eye may or may not “wander.” The weaker eye is called the "lazy eye."
• Astigmatism: A defect that causes an inability to properly focus light onto the retina. Astigmatism causes blurry vision that can be corrected with glasses or contact lenses.
• Cataract: A clouding of the lens, which hinders the passage of light through the lens.
• Conjunctivitis: Also known as "pinkeye,” conjunctivitis is an infection or inflammation of the conjunctiva. It is usually caused by allergies, a virus, or a bacterial infection.
• Glaucoma: Increased pressure inside the eye slowly reduces vision. Peripheral vision is lost first, often going undetected for years.
• Diplopia (double vision): Seeing double can be caused by many serious conditions. Diplopia requires immediate medical attention.
• Retinal detachment: The retina comes loose from the back of the eye. Trauma and diabetes are common causes of this medical emergency.
• Diabetic retinopathy: High blood sugar damages blood vessels in the eye. Eventually, weakened blood vessels may overgrow the retina or bleed, threatening vision.
• Stye: Bacteria infect the skin on the edge of the eyelid, creating a tender red bump.
• Chalazion: An oil-making gland gets blocked and swells into a bump. Often confused with styes, chalazions are not caused by infections.
• Hyphema: Bleeding into the front of the eye, behind the cornea. Hyphema is usually caused by trauma.
• Blepharitis: Inflammation of the eyelids near the eyelashes. Blepharitis is a common cause of itching or a feeling of grit in the eyes.
• Corneal abrasion: A scratch on the clear part of the front of the eye. Pain, light sensitivity, or a feeling of grit in the eye are the usual symptoms.
• Keratitis: Inflammation or infection of the cornea. Keratitis typically occurs after germs enter a corneal abrasion.
• Retinitis: Inflammation or infection of the retina. Retinitis may be a long-term genetic condition or result from a viral infection.
• Uveitis (iritis): The colored part of the eye becomes inflamed or infected. An overactive immune system, bacteria, or viruses can be responsible.
• Dry eye: Either the eyes don’t produce enough tears, or the tears are of poor quality. Dry eye can be caused by medical problems such as lupus, scleroderma, and Sjogren's syndrome.
• Optic neuritis: The optic nerve becomes inflamed, usually from an overactive immune system. Painful vision loss in one eye typically results.
• Black eye: Swelling and discoloration around the eye as a result of injury to the face.

KIDNEY

KIDNEY


The kidneys are dark-red, bean-shaped organs. One side of the kidney bulges outward (convex) and the other side is indented (concave). There is a cavity attached to the indented side of the kidney, called theRenal Pelvis... which extends into the ureter.

Each Kidney is enclosed in a transparent membrane called the renal capsule... which helps to protect them against infections and trauma.  The kidney is divided into two main areas... a light outer area called the renal cortex, and a darker inner area called therenal medulla. Within the medulla there are 8 or more cone-shaped sections known as renal pyramids. The areas between the pyramids are called renal columns.

Kidney Anatomy and Excretion

The most basic structures of the kidneys, are nephrons.  Inside each kidney there are about one million of these microscopic structures.  They are responsible for filtering the blood... removing waste products.

The renal artery delivers blood to the kidneys each day. Over 180 liters (50 gallons) of blood pass through the kidneys every day. When this blood enters the kidneys it is filtered and returned to the heart via therenal vein.

The process of separating wastes from the body's fluids and eliminating them, is known as excretion.  The body has four organ systems that are responsible for excretion.  The urinary system is one of the main organ systems responsible for excretion.  It excretes a broad variety of metabolic wastes, toxins, drugs, hormones, salts, hydrogen irons and water.  The kidneys are the main organs of the urinary system.

Kidney Anatomy and Blood Vessels

The kidneys are full of blood vessels.  Blood vessels are integral to efficient kidney function.  Every function of the kidney involves blood, therefore, it requires a lot of blood vessels to facilitate these functions. Together, the two kidneys contain about 160 km of blood vessels.








KIDNEY LOCATION
The normal kidney location is towards the back of the abdominal cavity, just above the waist. If you put your hands on your hips, your kidneys are located just about where your thumbs are. One kidney is normally located just below the liver, on the right side of the abdomen and the other is just below the spleen on the left side.
In rare cases, however, one or both kidneys may be located much lower in the abdomen. This is not necessarily a problem except probably in the case of pregnancy. As the fetus begins to develop in the womb this could sometimes place pressure on the kidney which is located in the lower abdomen. 










NORMAL KIDNEY SIZE


The normal kidney size of an adult human is about 10 to 13 cm (4 to 5 inches) long and about 5 to 7.5 cm (2 to 3 inches) wide. It is approximately the size of a conventional computer mouse.
A kidney weighs approximately 150 grams. Kidneys weigh about 0.5 percent of total body weight.




The human kidney anatomy, though relatively simple, enables it to perform extremely complex but essential functions. If any area of the kidney is damaged or becomes diseased, this could significantly affect its ability to perform these functions.

Heart

HEART

The heart is the organ that helps supply blood and oxygen to all parts of the body. 

It is divided by a partition or septum into two halves, and the halves are in turn 

divided into four chambers. The heart is situated within the chest cavity and 

surrounded by a fluid filled sac called the pericardium. This amazing muscle 

produces electrical impulses that cause the heart to contract, pumping blood 

throughout the body. The heart and the circulatory system together form the 

cardiovascular system.

• Heart Anatomy: Chambers

• Atria - upper two chambers of the heart.
• 
  
• Ventricles - lower two chambers of the heart.

Heart Anatomy: Heart Wall

• Epicardium - the outer layer of the wall of the heart.
• 
  
• Myocardium - the muscular middle layer of the wall of the heart.
• 
  
• Endocardium - the inner layer of the heart.

Heart Anatomy: Cardiac Conduction

Cardiac Conduction is the rate at which the heart conducts electrical impulses. The 

following structures play an important role in causing the heart to contract:

• Atrioventricular Bundle - bundle of fibers that carry cardiac impulses.
• 
  
• Atrioventricular Node - a section of nodal tissue that delays and relays cardiac 
• 
  
• impulses.
• 
  
• Purkinje Fibers - fiber branches that extend from the atrioventricular bundle.
• 
  
• Sinoatrial Node - a section of nodal tissue that sets the rate of contraction for 
• 
  
• the heart.

Heart Anatomy: Cardiac Cycle

The Cardiac Cycle is the sequence of events that occurs when the heart beats. 

Below are the two phases of the cardiac cycle:

• Diastole Phase - the heart ventricles are relaxed and the heart fills with blood.
• 
  
• Systole Phase - the ventricles contract and pump blood to the arteries.

Heart Anatomy: Valves

Heart valves are flap-like structures that allow blood to flow in one direction. 

Below are the four valves of the heart:

• Aortic Valve - prevents the back flow of blood as it is pumped from the left 
• 
  
• ventricle to the aorta.
• 
  
• Mitral Valve - prevents the back flow of blood as it is pumped from the left
•  
• atrium to the left ventricle.
• 
  
• Pulmonary Valve - prevents the back flow of blood as it is pumped from the 
• 
  
• right ventricle to the pulmonary artery.
• 
  
• Tricuspid Valve - prevents the back flow of blood as it is pumped from the right 
• 
  
• atrium to the right ventricle.