By Benjamin Cares

DIGESTION

Digestion consists of two types of digestion: chemical and physical. Chemical digestion involves complex molecular reactions and processes that help to run body systems and provide nutrients and energy in the body. Physical digestion moves and separates food so that it can be better broken down and absorbed by the body.



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Human Digestive System
PHYSICAL DIGESTION
Digestion begins when you put a piece of food in your mouth. By aid of the tongue and teeth the mouth can then chew or masticate food and break it down into smaller pieces. Saliva mixes with the food and forms a bolus which can then be moved into the pharynx and esophagus through the process of swallowing or deglutition by the tongue. When the bolus enters the esophagus, a process driven the external muscularis known as peristalsis forces food down through the digestive tract. The food reaches the cardioesophageal sphincter which prevents food from backing up the esophagus and causing indigestion. Once the food has enters the stomach peristalsis churns the food and assists in breaking it down into chyme. This chyme is shot out of the pyloric sphincter into the duodenum where further chemical processes break down chyme and peristalsis pushes it through the small intestine. After the duodenum the chyme enters the long and winding jejunum where microvilli help to move food along and absorb nutrients. After the jejunum the food enters the ileum where it then must pass the ileocecal valve and enters into the cecum. An important portion of the cecum is the appendix which can become infected when food allows bacteria to grow and causes an immune response which may cause the flesh like sac to burst and cause the organs to become septic, this is fixed through a procedure known as an appendectomy. After the chyme has passed the cecum it begins to transform as the intestines absorb water and will eventually become feces.The chyme travels up the ascending colon past the hepatic flexure across the transverse colon, past the splenic flexure, down the descending colon, into the sigmoid colon, and passes the anal canal and rectum before being defecated through peristalsis and the passage of the external anal sphincter.


CHEMICAL DIGESTION
To understand chemical digestion, we have to understand the molecular basis of the food we eat. Generally the food we eat can be separated into three categories: carbohydrates, protein, and fats.

CARBOHYDRATES: These molecules are the body's primary energy source because they can be broken down easily in the body. These molecules are made up of monomers of sugars. Monosacharide, disaccharide, and polysaccharides are carbohydrate molecules. These molecules consist of different kinds of sugars:
  • Monosaccharides
    • glucose and fructose
      • fruits
  • Disaccharides
    • sucrose, maltose, and lactose (milk sugar)
      • milk
  • Polysaccharides
    • starches
      • rice
PROTEINS: Protein molecules are chains of amino acids joined together by peptide bonds. When the amino acids are joined together in a large group as in proteins, they are known as polymers. Proteins are an interesting category in regard to nutrition because the food that we eat may not always contain all the types of amino acids our body needs. Proteins that do have all types are known as complete proteins and those that do not are incomplete proteins. A few examples of incomplete and complete proteins sources are listed below:
  • Complete
    • Steak
    • Chicken
    • Eggs
  • Incomplete
    • Beans
    • Peas
    • Nuts
FATS (Lipids): The fats that we consume are primarily triglycerides. There are two types of fats as well: unsaturated and saturated fats. The difference between these two fats involves how two carbon molecules are linked to one another in the triglyceride molecule. Though this may seem like a minor change in the structure of the triglyceride, it directly affects how the body will break it down.
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A few examples of fats include:
  • Olive oils
  • Fat on meat
  • Cashews


BREAKDOWN OF CARBOHYDRATES, PROTEINS, and FATS
Carbohydrates:
Carbohydrates are broken down firstly in the mouth by salivary amylase. Salivary amylase is able to break down simple carbohydrates into usable energy, these include galactose, glucose, and fructose. It also breaks down more complex carbohydrates, such as starch into simpler disaccharides and oligosaccharides. Carbohydrates continue to be broken down in the small intestine by pancreatic amylase and brush border enzymes such as dextrinase, gluccoamylase, lactase, maltase, and sucrase.

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Proteins:
Proteins are broken down in the stomach by pepsin which is converted from pepsinogen due to the prescense of HCl. Protein is first broken down into large polypeptides, followed by small polypeptides and peptides, and finally into amino acids. Proteins are broken down in the small intesetine by pancreatic enzymes and brush border enzymes.

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Fats:
Fats are broken down only in the small intestine. Fats must first be emulsified by bile salts from the liver. Once the fat has been emulsified it can be broken down by pancreatic lipase into monoglycerides, glycerol, and fatty acids.

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METABOLISM
Metabolism is defined as a totality of the bodies chemical reactions that are necessary to maintain life. Metabolism allows our body to utilize fats, proteins, and carbohydrates in a way that provides energy our organs need in order to work and keep us growing and in a homeostatic state. Metabolism can be separated into catabolism, which is when substances are broken down to simpler substances, and anabolism, in which larger molecules or structures are built from smaller ones. Each piece of food we eat enters different pathways, which allow us to utilize food in a different ways and allows a greater diversification of energy utilization that the body requires to run its complex systems.
The Krebs Cycle is responsible for providing ATP (adenosinetriphosphate). ATP is a basic unit of energy which drives the processes of our body by providing a form of energy for cellular processes. Glucose, or blood sugar, is absorbed into the body from foods and is then broken down into pyruvic acid in a process known as glycolosis. An electron transport chain is used as an area in which electrons can help to energize ADP moleucles and provide more ATP which runs The Krebs Cycle as well.
The liver is extremely important in regards to metabolism in the body. It not only detoxifies the blood but also stores glycogen which can later be used to provide energy in an process known as glycogenolysis. This is not to be confused with glycogenesis (genesis meaning generation), which is characterized by its ability to store glycogen from sugars in foods, this glycogen is stored in the liver as previously stated.
Some other aspects of the digestive system and metabolism include energy intake and output, the basal metabolic rate, which is the amount of heat produced by the body per unit of time when it is under basal conditions. The thyroid gland is also very important in monitoring metabolic rates by producing thyroxine.



The Endocrine System

The endocrine system is an extremely complex system of the body. It is responsible for the activation and functionality of our organs and maintains our bodies homeostasis and growth.The product of the endocrine organs is known as a hormone, a chemical substance that is released into the blood to evoke a specific response.
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CHEMISTRY OF HORMONES
Hormones can be defined as either amino acid-based molecules, steroids, and prostaglandins. Amino acid-based molecules includes proteins, peptides, and amines. Steroids include the sex hormones which are produced by the ovaries and testes (gonads). Hormones are also specific in their molecular structure which helps in the regulation where and when a hormone can produce a specific effects on the body.

MECHANISMS OF HORMONE ACTION
Hormones have specific target cells and target organs. Steroid hormones can are able to fit into a receptor protein in a lock and key method that allows only that steroid hormone to effect a specific cell. Non steroid hormones have a similar effect but take a nonsteroid first messenger and incorporate it into a receptor protein. The receptor protein then activates an enzyme that causes ATP to transfer to cAMP, which allows for further effects on cellular function and glycogen breakdown.

Steroid hormone action: steract_1.gif








Nonsteroid hormone action:first_4.gif

CONTROL OF HORMONE RELEASE:
The negative feedback mehcanism is the most important mechanism in the body for controlling homeostasis. The negative feedback system works simply by reacting to a decrease or increase in a specific substance that is above or below the norm and either activates or inhibits a specific production of a hormone. There are three different endocrine grand stimuli as well. Hormonal, humoral, and neural. Hormonal stimuli works by secreting hormones that activate other endocrine organs which causes them to release specific hormones. Humoral works by a negative feedback mechanism and works when specific levels of hormones or substances in the body trigger and endocrine gland sitmuli as needed. Neural stimuli works through a series of synapses which stimulate an endocrine organ to secrete specific hormones.

THE ENDOCRINE ORGANS:

Hypothalamus:
The Hypothalamus is the master endocrine organ and hormones released by the posterior pituitary and anterior pituitary are regulated by the hypothalamus.

Pituitary Gland:
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Approximately the size of a grape and is located within the brain.
The hormones of the anterior and posterior pituitary gland and general pituitary are as follows:
  • Oxytocin
    • Stimulates contraction of uterus and the milk reflex
  • Antidiuretic hormone (ADH)
    • Promotes retention of water by kidneys
  • Growth Hormone (GH)
    • general metabolic hormone that has its major effects in growth of skeletal and muscle tissues. Acromelagy and pituitary dwarfism are effects of the hypersecretion and hyposecretion of this hormone
  • Prolactin (PRL)
    • protein hormone structurally similar to growth hormone what stimulates milk flow and breast growth
  • Adrenocorticotropic hormone (ACTH)
    • regulates endocrine activity of the thyroid gland
  • Thyroid-stimulating hormone (TSH)
    • Stimulates thyroid gland
  • Follicle-stimulating hormone (FSH)
    • Stimulates production of ova and sperm
  • Luteinizing hormone (LH)
    • Stimulates ovaries and testes
  • Adrenocorticotropic hormone (ACTH)
    • Stimulates adrenal cortex to secrete glucocorticoids

Thyroid Gland:
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The thyroid gland is a hormone-producing gland that regulates body metabolism.
The hormones of the thyroid gland are as follows:
  • Thyroxine and Triiodthyronine
    • Stimulates metabolism
  • Calcitonin
    • Reduces blood calcium levels

Parathyroid Gland:
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Tiny masses of glandular tissue, known as the parathyroid glands, are found on the posterior layer of the thyroid gland. It is responsible in regulating the calcium blood levels.
  • Parathyroid hormone (PTH)
    • Raises blood calcium levels
Thymus Gland:
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This gland is located within the upper portion of the thorax and is located below the sternum. It is important in producing white blood cells and as an incubator for said blood cells in childhood development.
  • Thymosin
    • "Programs" T lymphocytes (white blood cell)
Adrenal Glands:
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The adrenal glands are located above the kidneys and are responsible for a variety of hormonal actions that result in the control and activation of the flight or fight response cycle and other internal mechanisms.
  • Epinephrine and norepinephrine
    • Raises blood glucose level; increase rate of metabolism; constrict certain blood vessels
  • Gluccocorticoids
    • Increase blood glucose
  • Mineralocorticoids
    • Promote re absorption of sodium and excretion of potassium in kidneys
  • Angiostensin II
    • potent stimulator of aldosterone release
  • Cortisol
    • cortisol increases fluidity in joins and promote skeletal health
Pancreas:
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The pancreas is located behind the stomach and is responsible for glucose and insulin levels in the body. Beta cells secrete insulin which helps to control glucose levels.
  • Insulin
    • Reduces blood glucose levels and is secreted by the beta cells
  • Glucagon
    • Raises blood glucose levels by converting stored sugars into glucose
The Gonads:
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The gonads consist of the ovaries and the testes. The ovaries are paired and produce two type of steroid hormones, estrogens and progesterone. The testes secrete androgens which aid in developing secondary male characteristics.
Testes:
  • Androgens
    • Support sperm formation; development and maintenance of male secondary sex characteristics
Ovaries
  • Estrogens
    • Stimulate uterine lining growth; development and maintenance of female secondary sex characteristics
  • Progesterone
    • Promotes growth of uterine lining

The endocrine system is one of the most important and vital systems in the body that controls our growth development and homeostatic nature.


THE SKELETAL SYSTEM


Functions of Bones
Bones contribute a variety of functions to the body. Support comes from the steel girders of bones that act as pillars and support the trunk and extremities of the body. Protection to the organs by the rib cage and the vertebral column of the spine provides a means of encasing our most important organs and protecting them from damage. Movement is allowed by the skeletal muscles and ligaments that attach to the bones and muscles of the bodyk, allowing movement. Storage of the bones allows fat and white blood cells in bone marrow to be stored in the hard casing of calcium.

Classification of Bones
There are six types of bones.
  • Compact bone
  • Spongy bone
  • Long bone
  • Short bones
  • Flat bones
  • Irregular bones

Axial Skeleton

The Skull
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The cranium and facial bones of the skull help to encase the brain and provide a bases for ligaments and muscles that aid in the movement of the eyes and the mouth. The most important cranial bones are listed below.

Frontal Bone
Forms the forehead and bony projections under the eyebrows.
Parietal Bones
Form the most of the superior and lateral walls of the cranium. It contains the sagittal suture and the coronal suture.
Temporal Bones
The temporal bones lie inferior to parietal bones; they join them at the squamous sutures. The parts of the temporal bones include extrenal acoustic meatus, styloid process, zygomatic process, mastoid process, jugular foramen, internal acoustic meatus, and the carotid canal.
Occipital Bone
The occipital bone is the most posterior bone of the cranium and it contains the lambdoidal suture and the foramen magnum and the occipital condyles.
Sphenoid Bone
This bone is the butterfly-shaped sphenoid bone and spans the width of the skull, it is the keystone bone of the skull. It contains the sella turcica and the foramen ovale as well as the optic canal, superior orbital fissure, and sphenoid sinuses.

The bones of the face are listed below:
Maxillae
These bones fuse to form the upper jaw. The maxillary bones,alveolar margin, palatine processes, sinuses, and paranasal sinuses are part of the maxillae.
Palatine Bones
They form the posterior part of the hard palate, failure of these bones to fuse causes a cleft palate.
Zygomatic Bones
Commonly reffered to as the cheekbones. Form a good-sized portion of the lateral walls of the orbits, or eye sockets.
Lacrimal Bones
Fingernail-size bones forming medial walls of each orbit. Passage way for tears.
Nasal Bones
Small rectangular bones forming the bridge of the nose are the nasal bones.
Vomer Bone
The single bone in the median line of the nasal cavity is the vomer.
Inferior Nasal Conchae
Thin curved bones projecting from the lateral walls of the nasal cavity.

The mandible, or lower jaw, is the largest and strongest bone of the face. It contains the alveolar margins.
The Hyoid Bone
Closely related to the mandible and temporal bones. \

Vertebral Column (Spine)

The spine is responsible for housing our spinal cord. It consists of the cervical, thoracic, lumbar, sacrum, and coccyx bones.

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The vertebral column is separated into five different sections.
  1. Cervical curvature
    1. These are composed of the C1 to C7 vertebra and consists of the atlas and axis
  2. Thoracic curvature
    1. These are composed of the T1 to T12 vertebra and consists of the tansverse process and spinous process
  3. Lumbar curvature
    1. The lumbar curvature consists of the L1 to L5
  4. Sacrum
    1. This bone consists of five fused vertebrae
  5. Coccyx
    1. This bone consists of four fused vertebrae

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The bony thorax is comprised of the sternum and ribs.

Ribs:
These consist of twelve pairs of long bones, they are comprised of the true ribs, the false ribs and the floating ribs.
Sternum:
The sternum is a typical flat bone and the result of the fusion of three bones, these bones consist the manubrium, body, and xiphoid process.

Appendicular Skeleton

The appendicular skeleton is composed of 126 bones of the appendages, the pectoral girdle, the pelvic girdle, and the limbs to the axial skeleton.

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Bones of the shoulder girdle:
  • clavicle
  • scapulae
  • acromion
  • coracoid process
  • acromioclavicular joint
  • suprascapular notch

Bones of the upper limbs

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  • Arm
    • humerus
    • greater and lesser tubercles
    • deltoid tuberosit
    • radial groove
    • trochlea
    • capitulum
    • coranoid fossa
    • olecranon fossa
    • medial and lateral epicondyles
  • Forearm
    • radius
    • radioulnar joints
    • interosseous membrane
    • styloid process
    • radial tuberosity
    • ulna
    • coranoid process
    • olecranon process
    • trochlear notch
  • Hand
    • carpal bones
    • carpus
    • metacarpals
    • phalanges
Bones of the Pelvic Girdle:

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  • Pelvic girdle
  • ossa coxae
  • hip bones
  • ilium
  • sacrioiliac joint
  • iliac crest
  • anterior superior liliac spine
  • ischium
  • pubis or pubic bone
  • false pelvis
  • true pelvis
Bones of the Lower Limbs
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  • Thigh
    • femur
    • trochanters
    • gluteal tuberosity
    • lateral and medial condyles
    • intercondylar fossa
  • Leg
    • tibia fibula
    • lateral malleolus
  • Foot
    • tarsus
    • calcaneus
    • talus
    • metatarsals
    • phalanges

Joints

There are three different kinds of joints
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  • Fibrous joints
    • bones are united by fibrous tissue, the best example is the joint in the sutures of the skull
  • Cartilaginous joints
    • bones ends are conected to cartilage, examples include the slihglty moval pubic symphsis and intervetebral joints
  • synovial joints
    • those in which the articulating synovial fluid account for all joints of the limbs
There are different types of synovial joints based on shape
  • plane joints
    • the articular surfaces are essentially flat, and only short slipping or gliding movements are allowed
  • hing joints
    • the cylindrical end of one bone fits into a trough-shaped surface on another bone
  • pivot joints
    • the rounded end of one bone fits into a sleeve or ring of bone

Joints can develop arthritis:
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  • Osteoarthritis (OA)
    • most common form of arthritis is a chrnoic degenerative condition that typically affects the aged, it is also called the wear-and-tear arthritis
  • Rheumatoid arthritis (RA)
    • chronic inflammatory disorder, its onset is insidious and usually occurs between the ages of 40 and 50 but it may occur at any age
  • Gouty arthritis
    • a disease which uric acid accumulates int he blood and may be deposited as needle-shaped crystals in the soft tissues


MUSCULAR SYSTEM

There are three types of muscle tissue:

  1. Skeletal muscle
    1. These are comprised of skeletal muscle fibers and are used to connect to the body's skeleton as insertion and origin points, striated muscle and voluntary muscle are used in the skeletal muscle structure. The skeletal muscle is comprised of the endomysium, perimysium, fascicle, epimysium, tendons, and aponeuroses
  2. Smooth muscle
    1. This type of muscle fiber has no striations and is involuntary. Involuntary muscle fibers are those that cannot be controlled by the brain at a persons will. These types of muscle tissues are used in the organs of the body and an important function is peristalsis.
  3. Cardiac muscle
    1. This type of muscle fiber is found in only one place in the body, the heart. It is characterized with striated muscle fibers and must be very strong to be able to maintain the strength and contractions of the heart
Muscles are important for a variety of reasons:
Producing Movement:
Muscles control almost every single movement in the human body and can do this through contraction and elonngation
Maintaining Posture:
Muscles in the rectus abdomnalis and the latissimus dorsi muscles are very important in helping maintain posture.
Stablizing Joints:
WIthout muscles we would not be able to move our limbs and maintain stances such as standing,sitting, and a variety of other positions.
Generating Heat:
Muscles generate heat by using ATP to power their processes and giving off heat as a byproduct of metabolic cycles.

THE SLIDING FILAMENT MODEL:
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The sliding filament model is comprised of the following:
  • sacrolemma
    • muscle cells
  • myofibrils
    • fill the cytoplasm
  • I bands
  • A bands
  • Sarcomeres
    • aligned end to end like boxcars in a train along the length of the myofibrils
  • Myofilaments
    • comprised of thick filaments known as myosin filaments
  • Myosin
    • protein that aids in contraction
  • Thin filaments
  • Actin
    • contractile protein
THE NEUROMUSCULAR JUNCTION
The neuromuscular junction is important in the stimulation of muscles to contract and the overall movement of the human body.
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Action potentials occur at the neuromuscular junction and are controlled by the release of Na and the absorption of K to produce Acetylcyholine and cause an electrochemical signal that allows the muscle to contract and utilizes ATP generated by the body.

TYPES OF BODY MOVEMENTS
  • Flexion
    • Decresases the angle of the joint and brings tow bones closer together
  • Extension
    • Opposite of flexion, so it is a movement that increases the angle
  • Rotation
    • movement of a bone around its longitudinal axis
  • Abduction
    • moving a limb away from the midline
  • Adduction
    • opposite of abduction, the movement of a limb toward the body midline
  • Circumduction
    • combination of flexion, extension, abduction, and adduction commonly seen in ball-and-socket joints such as the shoulder

GROSS ANATOMY OF SKELETAL MUSCLES

Head and Neck Muscles
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  • Frontalis
    • covers the frontal bone as it runs form the cranial aponeurosis to the skin of the eyebrows
  • Orbicularis Oculi
    • fibers that run in circles around the eyes
  • Buccinator
    • fleshy muscle that runs horizontally across the cheek and inserts into the orbicularis oris
  • Zygomaticus
    • extends from the corner of the mouth to the cheekbone
  • Masseter
    • covers the angle of the lower jaw as it runs from the zygomatic process of the temporal bone to the mandible
  • Temporalis
    • Fan-shaped muscle overlying the temporal bone
  • Platysma
    • single sheetlike muscle that covers the anterolateral neck
  • Sternocleidomastoid
    • two headed muscles one found on each side of the neck, flex the neck
TRUNK MUSCLES
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  • Pectoralis Major
    • large fan-shaped muscle covering upper part of the chest, origin is from sternum,inserts at proximal end of the humerus
  • Intercostal Muscles
    • deep muscles found between the ribs
  • Muscles of the Abdominal Girdle
    • anterior abdominal muscles
      • Rectus abdominis
        • superficial muscles of abdomen
      • External oblique
        • lateral walls of the abdomen
      • Internal oblique
        • paired muscles deep to the external obliques
      • Transversus abdominis
        • deepest muscle of the abdominal wall
  • Trapezius
    • most superficial muscles of the posterior neck and upper trunk
  • Latissimus Dorsi
    • large, flat muscle pair that covers the lweor back
  • Erector Spinae
    • prime mover of back extension
  • Deltoid
    • fleshy, triangle-shaped muscles that form the rounded shape of shoulder
MUSCLES OF THE UPPER LIMB
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  • Biceps Brachii
    • the most familiar muscle of the forearm because it bulges when the elbow is flexed
  • Brachialis
    • lies deep to the biceps muscle and is important in flexion
  • Brachioradilais
    • weak muscle that arises on the humerus and inserts in the distal forearm
  • Triceps Brachii
    • three heads, boxer muscle
MUSCLES OF THE LOWER LIMB
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  • Gluteus Maximus
    • powerufl hip extensor
  • Gluteus Medius
    • hip abductor and is important in steadying the pelvis during walking
  • Iliposoas
    • prime over of hip flexion
  • Adductor Muscles
    • form the muscle mass of the medial side of each thigh
  • Hamstring Group
    • biceps femoris, semimembranosus, semiteninosus
  • Sartorius
    • thin straplike sartorius, weak thigh flexor
  • Quadriceps Group
    • rectus femoris, vastus muscles
  • Tibilais Anterior
    • superficial muscle acts to dorsiflex and invert the foot
  • Extensor DIgitorum Longus
    • lateral to the tibialis anterior, this muscle arises from the lateral tibial condyle, prime mover of toe extension and dorsiflexor of the foot\
  • Fibularis Muscles
    • longus, brevis, tertius
  • Gastrocnemius
    • two bellied muscle that forms the curved calf of the posterior leg
  • Soleus
    • strong plantar flexor of the foot
Developmental Aspects of the Muscular System
  • Duchenne's muscular dystrophy
    • expressed almost exclusively in males, disease of sacrolemma


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THE REPRODUCTIVE SYSTEM

The reproductive system is one of the only systems that does not come to full maturity in childhood. The system remains dormant until puberty, in which the individual becomes mature enough to copulate and carry a child.
The gonads, or primary sex organs, consists of the testes and ovaries. Males have testes and females have ovaries.

ANATOMY OF THE MALE REPRODUCTIVE SYSTEM

Testes:
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The testes are olive-sized and are comprised of a fibrous connective tissue capsule, the tunica albuginea. The seminiferous tubules, are the sperm forming tubes of the testes.
The testes are comprised of a duct system which contains the epididymis, the ductus deferens, also known as the vas deferens, the spermatic cord, the ejaculatory duct, and the urethra.
The epididymis, is a highly coiled tube4 in the usperior part of the testis and runs down the posterolateral side. This is the first part of the male duct system and provides a temporary storage site for the immature sperm.
The vas deferens runs upward from the epididymis through the inguinal canal into the pelvic cavity and arches over the superior aspect. It is enclosed in the connective tissue sheath known as the spermatic cord. The ejaculatory duct, passes through the prostate gland to merge with the urethra, aids in propelling the sperm during ejaculation
The urethra extends form the base of the urinary bladder to the tip of the penis, there are three named regions of the urethra. The prostatic urethra, surrounded by the prostate gland, the membranous urethra, spanning the distance from the prostatic urethra to the penis, and the spongy urethra, running within the length of the penis.
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THE ACCESSORY GLANDS AND SEMEN
The seminal vesicles , located at the base of the bladder, produce about 60% of the fluid volume of semen. The substance secreted is rich in fructose, Vitamin C, prostaglandins, and other nutritious substances that aid in fertilizing the egg.
The prostate gland is a single gland about the size and shape of a chestnut. The prostate gland secretes a substance that helps to activate the role of sperm in fertilizaiton.
The bulbourethral Glands, are tiny, pea-sized glands inferior to the prostate gland that are supposed to cleanse the traces of acidic urine, and as a lubricant during intercourse.

EXTERNAL GENITALIA
The external genitalia consists of the following components:
  • scrotum
  • penis
  • shaft
  • glands penis
  • prepuce (foreskin)

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The primary function of the external male genitalia is to allow for the process of sexual intercourse to take place and to ensure that the sperm reaches the egg.

SPERMATOGENESIS

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  1. Spermatogonia, found on the outer edge of each tubule, goes through rapid mitotic divisions to build up the stem cell line. FSH is secreted in increasing amounts by the anterior pituitary gland and each division of the spermatogonium produces one stem cell, and another type of cell known as a type B daughte rcell.
  2. Primary spermatocyte undergoes meisosis and produces four sperm. Meisosis consist of two successive divisions of the nucleus.
  3. Spermatids are gametes that have only half as much genetic material as other body cells. As meisosis occurs, the dividing cells are pushed toward the lumen of the tubule.
  4. Spermatogenesis leads to the excess cytoplasm in the cell to be sloughed off, and what remains is copmacted into three regions of the mature sperm. These are the head, midpiecfe, and tail.
    1. The head of the sperm consist of acrosome, it is responsible in breaking down the protective barrier of the egg cell so that fertilization can occur.
TESTOSTERONE PRODUCTION
The luteinizing hormone, activates the interstitial cells which can then begin producing testosterone. Testosterone leads to the development of secondary male characteristics such as hair growth, muscle bulk, and narrower hips.

Anatomy of the Female Reproductive System

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The Ovaries:
the ovaries are a pair of almond sized shaped organs that are responsible for ousing the ovarian follices and the oocyte. As the devleoping egg within a follicle begins to ripen or mature, the follicle enlarges and develops a fluid-filled central region called an antrum. The follicle, now known as a Graafian follicle, is mature and ovulation can begin.
The Duct System:
The duct system consists of the fallopian tubes, the uterus, and the vagina.
Fallopian tubes: the initial part of the duct system, they recieve the ovulated oocyte and provide a site where fertilization can occur. The fallopian tube also consists of finger-like projectiosn called the fimbriae.
The Uterus: Also konwn as the womb, it is located inthe pelivs betweene the urinary bladder and rectum. It is a hollow organ that functions to receive, retain, and nourish a fertilized egg. The uterus is suspended in the pelivs by the proad ligament and anchored anteirorly and posteiroly by the round and uterosacral ligaments.
The major portion of the uterus is reffered to as the body. The entrance of the uterine tubes is the fundus, and the narrow outlet, which protrudes into the vagina below, is the cervix.
The wall of the uterus is thick and composed of three layers, the endometrium, the myometrium, and the perimetrium.
The Vagina: is a thin walled tube 8 to 10 cm long. It lies between the bladder and rectum and extends from the cervix to the body exterior.
Hymen: this is a very vascular and tends to bleed when it is ruptured during the first sexual intercourse.

EXTERNAL GENITALIA
The external genitalia consists of the following:
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  • mons pubis
  • labia majora
  • labia minora
  • vestibule
  • greater vestiublar glands
  • clitoris
  • perinium
The primary function of the external genitalia is to protect the vagina cavity and stimulate lubrication during sexual intercourse. The outlet of the bladder is also located in the external genitalia.

OOGENSIS