Nervous System

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Kaan Yücel M.D., Ph.D. 13.
15.September. 2011 Thursday
20. September. 2011 Tuesday
 It is important for medical personnel to have a sound
knowledge and understanding of the basic anatomic terms.
 The accurate use of anatomic terms by medical personnel
enables them to communicate with their colleagues both
nationally and internationally.
 Without anatomic terms, one cannot accurately discuss or
record the abnormal functions of joints, the actions of muscles,
the alteration of position of organs, or the exact location of
swellings or tumors.
Anatomical terms are descriptive terms standardized in an
international reference guide, Terminologia Anatomica (TA).
TA- International Anatomical Terminology
Created by the Federative Committee on Anatomical Terminology and
approved by the International Federation of Associations of Anatomists,
the most recent (6th) edition was published in 1998.
Many anatomical terms have both Latin and Greek equivalents.
Thus the tongue is lingua (L.) and glossa (Gk), and these are the
basis of such terms as lingual artery and glossopharyngeal
nerve.
 Various adjectives, arranged as pairs of opposites, describe the
relationship of parts of the body or compare the position of two
structures relative to each other.
 Anatomical directional terms are based on the body in the
anatomical position
 Four anatomical planes divide the body, and sections divide the
planes into visually useful and descriptive parts.
Terms Related to Position
 All descriptions of the human body are based on th anatomic position.
 The various parts of the body are then described in relation to certain
imaginary planes.
Median Sagittal Plane
This is a vertical plane passing through the center of the body, dividing it
into equal right and left halves.
.
Coronal Planes
Imaginary vertical planes at right angles to the median plane.
Horizontal, or Transverse,or Axial Planes
At right angles to both the median and the coronal planes.
Anatomical terms are specific for comparisons made in the anatomical
position, or with reference to the anatomical planes:
• Superior refers to a structure that is nearer the vertex, the topmost
point of the cranium (Mediev. L., skull).
• Inferior refers to a structure that is situated nearer the sole of the
foot.
• Cranial relates to the cranium and is a useful directional term,
meaning toward the head or cranium.
• Caudal (L. cauda, tail) is a useful directional term that means toward
the feet or tail region, represented in humans by the coccyx (tail
bone), the small bone at the inferior (caudal) end of the vertebral
column.
• Posterior (dorsal) denotes the back surface of the body or nearer to
the back.
• Anterior (ventral) denotes the front surface of the body.
• Rostral is often used instead of anterior when describing parts of the
brain; it means toward the rostrum (L. for beak).
To describe the relationship of two structures, one is said to be anterior
or posterior to the other insofar as it is closer to the anterior or
posterior body surface.
Medial is used to indicate that a structure is nearer to the median plane
of the body. For example, the 5th digit of the hand (little finger) is
medial to the other digits.
Lateral stipulates that a structure is farther away from the median
plane. The 1st digit of the hand (thumb) is lateral to the other digits.
Dorsum usually refers to the superior aspect of any part that protrudes
anteriorly from the body, such as the dorsum of the tongue, nose, penis,
or foot
.
• Combined terms describe intermediate positional arrangements:
inferomedial means nearer to the feet and median plane—for
example, superolateral means nearer to the head and farther
from the median plane.
Other terms of relationship and comparisons are independent of the
anatomical position or the anatomical planes, relating primarily to the
body's surface or its central core:
Superficial, intermediate, and deep (Lat. Profundus, profunda) describe
the position of structures relative to the surface of the body or the
relationship of one structure to another underlying or overlying
structure.
External means outside of or farther from the center of an organ or
cavity, while internal means inside or closer to the center, independent
of direction.
Other terms of relationship and comparisons are independent of the
anatomical position or the anatomical planes, relating primarily to the
body's surface or its central core:
External means outside of or farther from the center of an organ or
cavity, while internal means inside or closer to the center, independent
of direction.
Proximal and distal are used when contrasting positions nearer to or
farther from the attachment of a limb or the central aspect of a linear
structure (origin in general), respectively. For example, the arm is
proximal to the forearm and the hand is distal to the forearm.
Terms of Laterality
 Paired structures having right and left members (e.g., the kidneys) are
bilateral, whereas those occurring on one side only (e.g., the spleen)
are unilateral.
 Something occurring on the same side of the body as another
structure is ipsilateral.
 Contralateral means occurring on the opposite side of the body
relative to another structure.
Terms of Movement
 Various terms describe movements of the limbs and other parts
of the body.
 Most movements are defined in relationship to the anatomical
position, with movements occurring within, and around axes
aligned with, specific anatomical planes.
 While most movements occur at joints where two or more bones
or cartilages articulate with one another, several non-skeletal
structures exhibit movement (e.g., tongue, lips, eyelids).
Terms of movement may also be considered in
pairs of oppositing movements:
Flexion and extension movements generally occur in
sagittal planes around a transverse axis.
Flexion indicates bending or decreasing the angle between the bones or
parts of the body. For most joints (e.g., elbow), flexion involves
movement in an anterior direction, but it is occasionally posterior, as in
the case of the knee joint.
Lateral flexion is a movement of the trunk in the coronal plane.
Extension indicates straightening or increasing the angle between the
bones or parts of the body. Extension usually occurs in a posterior
direction.
The knee joint, rotated 180° to other joints, is exceptional in that flexion
of the knee involves posterior movement and extension involves
anterior movement.
Dorsiflexion describes flexion at the ankle joint, as occurs when walking
uphill or lifting the front of the foot and toes off the ground.
Plantarflexion bends the foot and toes toward the ground, as when
standing on your toes.
Abduction and adduction movements generally occur in a frontal
plane around an anteroposterior axis.
Except for the digits, abduction means moving away from the median
plane (e.g., when moving an upper limb laterally away from the side of
the body) and adduction means moving toward it.
Circumduction is a circular movement that involves sequential flexion,
abduction, extension, and adduction in such a way that the distal end of
the part moves in a circle.
Circumduction can occur at any joint at which all the above-mentioned
movements are possible (e.g., the shoulder and hip joints).
•
•
Rotation involves turning or revolving a part of the body around its
longitudinal axis, such as turning one's head to face sideways.
Medial rotation (internal rotation) brings the anterior surface of a
limb closer to the median plane, whereas lateral rotation (external
rotation) takes the anterior surface away from the median plane.
• Pronation rotates the radius medially so that the palm of the hand
faces posteriorly and its dorsum faces anteriorly. When the elbow
joint is flexed, pronation moves the hand so that the palm faces
inferiorly (e.g., placing the palms flat on a table).
• Supination is the opposite rotational movement, rotating the radius
laterally and uncrossing it from the ulna, returning the pronated
forearm to the anatomical position. When the elbow joint is flexed,
supination moves the hand so that the palm faces superiorly.
Eversion moves the sole of the foot away from the median plane,
turning the sole laterally.
Inversion moves the sole of the foot toward the median plane (facing
the sole medially).
Opposition is the movement by which the pad of the 1st digit (thumb) is
brought to another digit pad. This movement is used to pinch, button a
shirt, and lift a teacup by the handle.
Reposition describes the movement of the 1st digit from the position of
opposition back to its anatomical position.l
Protrusion is a movement anteriorly (forward) as in protruding the
mandible (chin), lips, or tongue.
Retrusion is a movement posteriorly (backward), as in retruding the
mandible, lips, or tongue.
Elevation raises or moves a part superiorly, as in elevating the shoulders
when shrugging.
Depression lowers or moves a part inferiorly, as in depressing the
shoulders when standing at ease.
Protraction and retraction are used most commonly for anterolateral
and posteromedial movements of the scapula on the thoracic wall,
causing the shoulder region to move anteriorly and posteriorly.
http://sinoemedicalassociation.org/AP/bodyregions.pdf
Body Planes
Figure 1.9a
Trunk Cavities
• Diaphragm: divides
body cavity into
thoracic and
abdominopelvic
cavities.
• Mediastinum:
contains all structures
of the thoracic cavity
except the lungs
Ventral Body Cavity Membranes
• Parietal serosa lines internal body walls
• Visceral serosa covers the internal organs
• Serous fluid separates the serosae
Serous Membranes
• Cover the organs of trunk cavities &
line the cavity
• Fist represents an organ
• Inner balloon wall represents
visceral serous membrane
• Outer balloon wall represents
parietal serous membrane
• Cavity between two membranes
filled with lubricating serous fluid
that is produced by the membranes
• Inflammation of the serous
membranes
Serous Membranes: Named for Their
Specific Cavities and Organs
– Pericardium refers to heart.
– Pleura refers to lungs and thoracic cavity.
– Peritoneum refers to abdominopelvic cavity.
Other Body Cavities
• Oral and digestive – mouth and cavities of the
digestive organs
• Nasal –located within and posterior to the
nose
• Orbital – house the eyes
• Middle ear – contain bones (ossicles) that
transmit sound vibrations
• Synovial – joint cavities
The skin (L. integumentum, a covering) is the body's largest
organ, consists of the epidermis, a superficial cellular layer,
and the dermis, a deep connective tissue layer.
The skeleton is composed of cartilages and bones.
Os = Bone
Osteologia
The skeletal system may be divided into two functional parts:
The axial skeleton consists of the bones of the head, neck, and trunk.
The appendicular skeleton consists of the bones of the limbs,
including those forming the pectoral (shoulder) and pelvic girdles.
Joints (articulations) are unions or junctions between two
or more bones or rigid parts of the skeleton. Joints exhibit a
variety of forms and functions.
• Some joints have no movement, such as the epiphysial
plates between the epiphysis and diaphysis of a growing
long bone.
• Others allow only slight movement, such as teeth within
their sockets.
• Some are freely movable, such as the glenohumeral
(shoulder) joint.
Myologia
Mus-culus= Muscle, Lat. Little mouse
The muscular system consists of all the muscles of the body.
 Voluntary skeletal muscles constitute the great majority of the
named muscles.
 All skeletal muscles are composed of one specific type of
muscle tissue.
 However, other types of muscle tissue constitute a few named
muscles (e.g., the ciliary and detrusor muscles, and the
arrector muscles of hairs) and form important components of
the organs of other systems, including the cardiovascular,
alimentary, genitourinary, integumentary, and visual systems.
There are three types of muscles:
1) Striated muscle (skeletal muscles)-voluntarily controlled, though
exceptions exist
2) Non-striated muscle (smooth muscle) - involuntary
3) Cardiac muscle
The heart consists of two muscular pumps that dividing the
circulation into two components: the pulmonary and systemic
circulations or circuits.
The right ventricle propels low-oxygen blood returning from the
systemic circulation into the lungs. Carbon dioxide is exchanged for
oxygen in the capillaries of the lungs, and then the oxygen-rich blood is
returned to the heart's left atrium.
This circuit, from the right ventricle through the lungs to the left atrium,
is the pulmonary circulation.
The left ventricle propels the oxygen-rich blood returned to the heart
from the pulmonary circulation, exchanging oxygen and nutrients for
carbon dioxide in the remainder of the body's capillaries. Low-oxygen
blood returns to the heart's right atrium.
This circuit, from left ventricle to right atrium, is the systemic
circulation.
Blood Vessels
There are three types of blood vessels: arteries, veins, and capillaries.
Blood under high pressure leaves the heart and is distributed to the
body by a branching system of arteries.
• The final distributing vessels, arterioles, deliver oxygen-rich blood
to capillaries.
• Capillaries form a capillary bed, where the interchange of oxygen,
nutrients, waste products, and other substances with the
extracellular fluid occurs.
• Blood from the capillary bed passes into venules, which resemble
wide capillaries.
• Venules drain into small veins that open into larger veins. The
largest veins return low-oxygen blood to the heart.
Large elastic arteries (conducting arteries) have many elastic layers
(sheets of elastic fibers) in their walls. These large arteries initially
receive the cardiac output.
Examples of large elastic arteries are the aorta, the arteries that
originate from the arch of the aorta (brachiocephalic trunk, subclavian
and carotid arteries), and the pulmonary trunk and arteries.
Medium muscular arteries (distributing arteries) have walls that consist
chiefly of circularly disposed smooth muscle fibers. Their ability to
decrease their diameter (vasoconstrict) regulates the flow of blood to
different parts of the body as required by circumstance (e.g., activity,
thermoregulation).
Most of the named arteries, including those observed in the body wall
and limbs during dissection such as the brachial or femoral arteries, are
medium muscular arteries.
Small arteries and arterioles have relatively narrow lumina and thick
muscular walls. The degree of filling of the capillary beds and level of
arterial pressure within the vascular system are regulated mainly by the
degree of tonus (firmness) in the smooth muscle of the arteriolar walls.
If the tonus is above normal, hypertension (high blood pressure) results.
• Anastomoses (communications) between multiple branches of an
artery provide numerous potential detours for blood flow in case
the usual pathway is obstructed by compression due to the
position of a joint, pathology, or surgical ligation.
• If a main channel is occluded, the smaller alternate channels can
usually increase in size over a period of time, providing a collateral
circulation that ensures the blood supply to structures distal to
the blockage.
Lymphoid System
• Constitutes an “overflow” system that provides for the drainage of
surplus tissue fluid and leaked plasma proteins to the bloodstream, as
well as for the removal of debris from cellular decomposition and
infection.
• Lymph nodes, small masses of lymphatic tissue located along the
course of lymphatic vessels through which lymph is filtered on its way
to the venous system.
 The nervous system enables the body to react to continuous
changes in its internal and external environments.
 It also controls and integrates the various activities of the
body, such as circulation and respiration.
 Nervous system controls the systems in the body and
regulates its functions according to the impulses received
from the outer world (sensations)
 The nervous system controls and integrates the activities of
the different parts of the body together with the endocrine
system,
 Nervous system controls the systems in the body and
regulates its functions according to the impulses received
from the outer world (sensations)
 The nervous system controls and integrates the activities of
the different parts of the body together with the endocrine
system.
For descriptive purposes, the nervous system is
divided:
• Structurally
1. Central nervous system (CNS) (MSS in Turkish)
brain and spinal cord
2. Peripheral nervous system (PNS)
remainder of the nervous system outside of the CNS.
• Functionally
1. Somatic nervous system (SNS)
2. Autonomic nervous system (ANS)
Nervous tissue consists of two main cell types:
• Neurons (nerve cells)
• Neuroglia (glial cells), which support the neurons.
• Neurons are the structural and functional units of the nervous system
specialized for rapid communication.
• Neuroglia (glial cells or glia), approximately five times as abundant as
neurons, are non-neuronal, non-excitable cells that form a major
component of nervous tissue, supporting, insulating, and nourishing
the neurons.
A smear from a mammalian spinal cord showing an isolated neuron (large arrow) and the nuclei of the
surrounding neuroglial cells (small arrows).
The principal roles of the CNS are to integrate and coordinate
incoming and outgoing neural signals and to carry out higher mental
functions, such as thinking and learning.
The peripheral nervous system (PNS) consists of nerve
fibers and cell bodies outside the CNS that conduct
impulses to or away from the CNS. The PNS is organized
into nerves that connect the CNS with peripheral
structures.
PNS is anatomically and operationally continuous with the CNS.
 Its afferent (sensory) fibers convey neural impulses to the CNS
from the sense organs (e.g., the eyes) and from sensory
receptors in various parts of the body (e.g., in the skin).
 Its efferent (motor) fibers convey neural impulses from the CNS
to effector organs (muscles and glands).
Nerves are either cranial nerves or spinal nerves, or
derivatives of them.
Cranial nerves exit the cranial cavity through foramina
(openings) in the cranium (G. kranion, skull) and are identified
by a descriptive name (e.g., “trochlear nerve”) or a Roman
numeral (e.g., “CN IV”).
 Spinal (segmental) nerves exit the vertebral column (spine).
 Spinal nerves arise in bilateral pairs from a specific segment
of the spinal cord.
 The 31 spinal cord segments and the 31 pairs of nerves
arising from them are identified by a letter and number (e.g.,
“T4”) designating the region of the spinal cord and their
superior-to-inferior order (C, cervical; T, thoracic; L, lumbar;
S, sacral; Co, coccygeal).
Cranial Nerves
Some cranial nerves convey only sensory fibers, some only motor fibers,
and some carry a mixture of both types of fibers.
1. Cranial nerve i - olfactory (sensory)
2. Cranial nerve ii - optic (sensory)
3. cranial nerve iii - Oculomotor (sensory and
motor)
4. Cranial nerve iv - trochlear (motor)
5. Cranial nerve v - trigeminal (sensory and
motor)
6. Cranial nerve vi - abducent (motor)
7. Cranial nerve vii - facial (sensory and motor)
8. Cranial nerve viii - vestibule cochlear
(sensory)
9. Cranial nerve ix - glosspharyngeal (sensory
and motor)
10. Cranial nerve x - Vagus (sensory and
motor)
11. Cranial nerve xi accessory (motor)
12. Cranial nerve xii - hypoglossal (motor)
Somatic and Visceral Fibres
The types of fibers conveyed by cranial or spinal nerves:
Somatic fibers
General sensory fibers (general somatic afferent [GSA] fibers) transmit
sensations from the body to the CNS; they may be exteroceptive
sensations from the skin (pain, temperature, touch, and pressure) or
pain and proprioceptive sensations from muscles, tendons, and joints.
Somatic motor fibers (general somatic efferent [GSE] fibers) transmit
impulses to skeletal (voluntary) muscles.
Visceral fibers
Visceral sensory fibers (general visceral afferent [GVA] fibers) transmit
pain or subconscious visceral reflex sensations (information concerning
distension, blood gas, and blood pressure levels, for example) from
hollow organs and blood vessels to the CNS.
Visceral motor fibers (general visceral efferent [GVE] fibers) transmit
impulses to smooth (involuntary) muscle and glandular tissues.
Somatic Nervous System
The somatic nervous system (SNS), composed of somatic parts of the
CNS and PNS, provides sensory and motor innervation to all parts of the
body (G. soma), except the viscera in the body cavities, smooth muscle,
and glands.
 The somatic sensory system transmits sensations of touch, pain,
temperature, and position from sensory receptors.
 Most of these sensations reach conscious levels (i.e., we are aware
of them).
 The somatic motor system innervates only skeletal muscle,
stimulating voluntary and reflexive movement by causing the muscle
to contract, as occurs in response to touching a hot iron.
Autonomic Nervous System (Visceral Nervous System)
The autonomic nervous system (ANS), classically described as the
visceral nervous system or visceral motor system, consists of motor
fibers that stimulate smooth (involuntary) muscle, modified cardiac
muscle (the intrinsic stimulating and conducting tissue of the heart), and
glandular (secretory) cells.
The efferent nerve fibers and ganglia of the ANS are organized into
two systems or divisions:
• Sympathetic division
• Parasympathetic division
• (craniosacral) division
The respiratory apparatus consists of the nose, nasopharynx,
paranasal sinuses, larynx, trachea, bronchi, lungs, and pleuræ.
Nose
• Consists of the external nose and the nasal cavity, both of which
are divided by a septum into right and left halves.
• Opens into the nasopharynx.
• An amazing humidifier and warmer of air.
The paranasal sinuses are cavities found in the interior of the maxilla,
frontal, sphenoid, and ethmoid bones. They are filled with air; they
communicate with the nasal cavity through relatively small apertures.
Infection of the paranasal sinuses is a common complication of nasal
infections.
We still are unsure as to all the functions of these air-filled spaces.
Multiple theories of function exist.
Nasopharynx
It is located posterior to the nose and superior to the soft palate. Being
one of the three parts of the pharynx, a structure belonging to the
digestive system, nasopharynx has a respiratory function. It is the
posterior extension of the nasal cavities. The nose opens into the
nasopharynx .
Larynx
•
•
•
•
Organ of voice voice box
Located between the trachea and the root of the tongue, at the
upper and forepart of the neck, where it presents a considerable
projection in the middle line.
Placed at the upper part of the air passage
Although most commonly known for its role as the phonating
mechanism for voice production, its most vital function is to guard
the air passages, especially during swallowing when it serves as the
“sphincter” or “valve” of the lower respiratory tract, thus maintaining
a patent airway.
Composed of nine cartilages connected by membranes and ligaments
and containing the vocal folds.
Trachea
• Extending from the larynx into the thorax, terminates inferiorly as
it divides into right and left main bronchi.
• Transports air to and from the lungs.
• A fibrocartilaginous tube, supported by incomplete cartilaginous
tracheal cartilages (rings), that occupies a median position in the
neck. The tracheal cartilages keep the trachea patent.
Pleura
Each pulmonary cavity (right and left) is lined by a pleural
membrane (pleura) that also reflects onto and covers the
external surface of the lungs occupying the cavities. Each lung
is invested by and enclosed in a serous pleural sac.
Lungs
• Vital organs of respiration.
• Main function is to oxygenate the blood
• Although cadaveric lungs may be shrunken, firm or hard, and
discolored, healthy lungs in living people are normally light, soft, and
spongy, and fully occupy the pulmonary cavities.
Tracheobronchial Tree
Beginning at the larynx, the walls of the airway are supported by
horseshoe- or C-shaped rings of hyaline cartilage. The trachea
constitutes the trunk of the tree. It bifurcates into main bronchi
(right and left main bronchi), one to each lung. Within the lungs,
the bronchi branch in a constant fashion to form the branches of
the tracheobronchial tree.
 The apparatus for the digestion of the food consists of the
digestive tube and of certain accessory organs.
 The Digestive Tube (alimentary canal) is a musculomembranous
tube, about 9 metres long, extending from the mouth to the anus,
and lined throughout its entire extent by mucous membrane.
It has received different names in the various parts of its course:
 At its commencement is the mouth, where provision is made for
the mechanical division of the food (mastication), and for its
admixture with a fluid secreted by the salivary glands
(insalivation)
 Beyond this are the organs of deglutition, the pharynx and the
esophagus, which convey the food into the stomach, in which it is
stored for a time and in which also the first stages of the digestive
process take place.
 Peristalsis, a series of ring-like contraction waves, begins around the
middle of the stomach and moves slowly toward the pylorus.
 It is responsible for mixing the masticated (chewed) food mass with
gastric juices and for emptying the contents of the stomach into the
duodenum.
 The stomach is followed by the small intestine, which is divided
for purposes of description into three parts, the duodenum, the
jejunum, and ileum.
 In the small intestine the process of digestion is completed and
the resulting products are absorbed into the blood and lacteal
vessels.
 Finally the small intestine ends in the large intestine, which is
made up of cecum, colon, rectum, and anal canal, the last
terminating on the surface of the body at the anus.
The accessory organs are the teeth, for purposes of mastication; the
three pairs of salivary glands—the parotid, submaxillary, and
sublingual—the secretion from which mixes with the food in the
mouth and converts it into a bolus and acts chemically on one of its
constituents.
The liver and pancreas, two large glands in the abdomen, the
secretions of which assist in the process of digestion.
Absorption of chemical compounds occurs principally in the small
intestine, a coiled 5- to 6-m-long tube (shorter in life, when tonus is
present, than in the cadaver) consisting of the duodenum, jejunum, and
ileum.
Most reabsorption of water occurs in the ascending colon.
Feces form in the descending and sigmoid colon and accumulate in the
rectum before defecation.
Peritoneum and Periotenal Cavity
The peritoneum is a continuous, serous membrane which lines the
abdominopelvic cavity and invests the viscera.
The peritoneal cavity is within the abdominal cavity and continues
inferiorly into the pelvic cavity.
Oral region includes:
• Oral cavity
• Teeth
• Gingivae
• Tongue
• Palate
• Region of the
palatine tonsils
•
The oral cavity is where food is ingested and prepared for digestion
in the stomach and small intestine.
•
Food is chewed by the teeth, and saliva from the salivary glands
facilitates the formation of a manageable food bolus (L. lump).
Pharynx
The pharynx is the superior expanded part of the alimentary system
posterior to the nasal and oral cavities, extending inferiorly past the
larynx.
Esophagus
The esophagus is a muscular tube that conveys food from the pharynx
to the stomach.
Stomach
 The stomach is the expanded part of the digestive tract between the
esophagus and small intestine.
 It is specialized for the accumulation of ingested food, which it
chemically and mechanically prepares for digestion and passage into
the duodenum.
 The stomach acts as a food blender and reservoir; its chief function is
enzymatic digestion.
Small Intestine
The small intestine, consisting of the duodenum, jejunum, and
ileum, is the primary site for absorption of nutrients from
ingested materials.
The duodenum (L. breadth of 12 fingers), the first and shortest part of
the small intestine, is also the widest and most fixed part.
The second part of the small intestine is the jejunum, whereas third
part is, the ileum. Together, the jejunum and ileum are 6-7 m long.
Large Intestine
The large intestine consists of the cecum; appendix; ascending,
transverse, descending, and sigmoid colon; rectum; and anal canal.
The large intestine is where water is absorbed from the indigestible
residues of the liquid chyme, converting it into semi-solid stool or feces
that is stored temporarily and allowed to accumulate until defecation
occurs.
Functions
1) Collect water and filter body fluids.
2) Remove and concentrate waste products from body fluids and
return other substances to body fluids as necessary for homeostasis.
3) Eliminate excretory products from the body.
Kidneys
 The ovoid kidneys remove excess water, salts, and
wastes of protein metabolism from the blood while
returning nutrients and chemicals to the blood.
 The kidneys produce urine that is conveyed by the
ureters to the urinary bladder in the pelvis.

The superomedial aspect of each kidney normally contacts a
suprarenal gland.
 A weak fascial septum separates the glands from the kidneys so
that they are not actually attached to each other.
 The suprarenal glands function as part of the endocrine system,
completely separate in function from the kidneys.
Ureters
The ureters are muscular ducts with narrow lumina that carry
urine from the kidneys to the urinary bladder.
Urinary bladder
 The urinary bladder, a hollow viscus with strong muscular walls, is
characterized by its distensibility.
 The urinary bladder is a temporary reservoir for urine and varies in
size, shape, position, and relationships according to its content and
the state of neighboring viscera.
Urethra
 The male urethra is a muscular tube that conveys urine from the
internal urethral orifice of the urinary bladder to the external
urethral orifice, located at the tip of the glans penis in males.
 The urethra also provides an exit for semen (sperms and glandular
secretions). The female urethra passes anteroinferiorly from the
internal urethral orifice of the urinary bladder.
 The endocrine system is made up of glands that produce and
secrete hormones.
 These hormones regulate the body's growth, metabolism (the
physical and chemical processes of the body), and sexual
development and function.
 The hormones are released into the bloodstream and may
affect one or several organs throughout the body. Hormones
are chemical messengers created by the body.
 They transfer information from one set of cells to another to
coordinate the functions of different parts of the body.
The major glands of the endocrine system
 Hypothalamus
 Pituitary gland
 Thyroid
 Parathyroids
 Suprarenal glands
 Pineal body
 The reproductive organs (ovaries and testes)
The pancreas is also a part of this system; it has a role in hormone
production as well as in digestion.
 The endocrine system is regulated by feedback in much the
same way that a thermostat regulates the temperature in a
room.
 For the hormones that are regulated by the pituitary gland,
a signal is sent from the hypothalamus to the pituitary gland
in the form of a "releasing hormone," which stimulates the
pituitary to secrete a "stimulating hormone" into the
circulation.
 The stimulating hormone then signals the target gland to secrete its
hormone.
 As the level of this hormone rises in the circulation, the
hypothalamus and the pituitary gland shut down secretion of the
releasing hormone and the stimulating hormone, which in turn
slows the secretion by the target gland.
 This system results in stable blood concentrations of the hormones
that are regulated by the pituitary gland.
Male internal genital organs
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Testes
Epididymides (singular = epididymis)
Ductus deferentes (singular = ductus deferens
Seminal glands
Ejaculatory ducts
Prostate
Bulbourethral glands
Female internal genital organs
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Ovaries
Uterine tubes
Uterus
Vagina
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