Endocrine System

CHAPTER IX

ENDOCRINE GLANDS

Exocrine Glands

-          Define as having ducts or tubes by which the secretions manufactured by them are discharged upon the skin surface or into the cavities of hollow organs.

Endocrine Glands

-          Ductless glands/gland of internal secretions, are nests or clumps of cells having no ducts.

Hormone

-          A secretion manufactured by an endocrine gland and directly into blood capillaries.

Double Glands

-          Have no distinct parts, each secreting its hormones.

Mixed Glands

-          Some glands have an endocrine part to secrete on or more hormones, and an exocrine part to secrete enzymes.

Gland with multiple functions

-          Some glands secrete more than one hormone.

Metabolism

-          A term used to include the chemical changes that occur in body cells as a result of cellular activity.

1.      Pituitary Gland / Hypophysis

-          Lies with the cranial cavity, in the pituitary fossa on the sella turcica.

1.1.Posterior Lobe / Neurohypophysis

-          Derived from a pouch of the third ventricle of the brain.

·         Oxytocin / Pitocin

-          Stimulates the muscle of the uterus to contract during child birth.

·         Antidiuretic Hormone (ADH) / Vasopressin

-          Stimulates the reabsorption of water from renal tubules.

1.2.Anterior Lobe / Adenohypophysis

-          Derived from a pouch of the mouth of the fetus.

·         Thyrotrophic Hormone (TSH)

-          Stimulates the thyroid gland to grow and to produce its hormone.

·         Adenocorticotrophic Hormone (ACTH)

-          Stimulates the cortex of the suprarenal gland to secrete its hormones.

Gonadotrophic hormones in the female:

·         Follicle Stimulating Hormone (FSH) and Luteinizing Hormone (LH)

-          Stimulate the ovaries in adolescents to mature, development of Graafian follicles and ova, production of estrogens – ovarian hormones, ovulation – discharge of ova, development of the corpus luteum and secretion of progesterone.

·         Leteotrophic Hormone (LTH) / Prolactin

-          Concerned with the enlargement of breast tissue for secretion of milk.

Gonadotrophic hormones in the male:

·         Follicle Stimulating Hormone (FSH)

-          Stimulates growth of testes, production of spermatozoa by the testis.

·         Interstitial Cell Stimulating Hormone (ICSH)

-          Stimulates production of androgens by the interstitial cells of the testis.

·         Somatotrophic Hormone (STH)

-          The growth stimulating hormone is concerned with the growth of the skeleton and other structures during childhood

·         Melanocyte Stimulating Hormone

-          Stimulate the formation of pigments in human.

2.      Pineal Gland / Body

-          Lies within the cranial cavity in the midline posterior to the midbrain.

3.      Thyroid Gland

-          Consists of two lobes, a right and a left lying in the anterior neck, one on either side of the thyroid cartilage.

·         Thyroxine and Tetraiodothyronine

-          Contain iodine that is obtained from water and food consumption.

-          It functions to promote mental and physical development in the young, and to stimulate metabolism in all age group.

4.      Parathyroid Gland

-          Four small bean shaped bodies that lie in the neck posterior to the thyroid gland.

·         Parathormone / Parathyroid Hormone

-          Functions for regulation of calcium metabolism, and its concentration in blood and tissues, especially in bones.

5.      Pancreas

-          A mixed gland with exocrine and endocrine parts.

-          The endocrine part consists of minute nets of cells, the Island (Islets) of Langerhans, that have no ducts, but secretes their hormones directly into blood capillaries.

·         Insulin and Glucagon

-          Function of insulin stimulates body cells to use up glucose to produce energy, and promotes its storage in the liver, thus regulating the blood sugar concentration.

-          Glucagon is said to have an opposite effect, promoting the release of glucose from the liver thus raising the blood sugar level.

6.      Suprarenal or Adrenal Gland

-          Flat caplike structures and lie upon the upper end of the corresponding kidney

6.1.Medulla

-          Central part.

·         Adrenaline / Norepinephrine

-          Have a similar effect to stimulation of the sympathetic part of the autonomic nervous system, and affect the same structures.

-          They can cause an increase in the rate of the heart beat, and cause contraction of blood vessels thus raising the blood pressure.

6.2.Cortex

-          Outer part.

·         Glucocorticoids

-          Concerned with the metabolism of glucose, amino acids and fats.

·         Mineralocorticoids

-          Help to regulate the electrolyte (salt) balance of blood and tissues by promoting the reabsorption of water and sodium from the renal tubules of the kidneys.

·         Gonadal Hormone

-          Female and male, similar to the hormones secreted by the ovaries and testes, but in lesser amounts.

7.      Gonads

7.1.Ovaries

·         Estrogens

-          Responsible for the development of the secondary sexual characteristics that appear at puberty (teen age). This includes enlargement of the breast, uterus, and vagina, the appearance of axilla and pubic hair, the maturing of the female figure, and personality changes with awareness of the male.

·         Progesterone

-          Hormone secreted by the corps luteum and, if pregnancy occurs, by the placenta or afterbirth.

-          Promotes development of the milk secreting cells of the breasts.

7.2.Testes

·         Androgens (Testosteron, Androsterone)

-          Male sex hormone secreted by the interstitial cells within the testes, and includes testosterone and androsterone: these are responsible for the changes that occur as puberty approaches.

-          The penis and other reproductive organs enlarge, the beard begins to grow, and the voice deepens.

-          The prostate and seminal vesicles become active, and personality changes occur.

Digestive System

1.      Gastrin

-          Hormone formed in the lining membrane of the pyloric part of the stomach.

2.      Secretin

-          Hormone formed in the lining membrane of the duodenum when stimulated by the preserve of fat, protein, or acid in the duodenum.

3.      Pancreozymin

-          Hormone secreted by the lining membrane of the small intestine.

4.      Cholecystokinin

-          Hormone secreted by interstitial mucosa when fat reaches the duodenum from ingested food.

Pathological Condition Affecting the Endocrine Glands

1.      Pituitary Gland

1.1.Giantism

-          Overgrowth of a subject due to an excessive secretion of the somatotraphic (growth hormone) of the anterior lobe of the pituitary gland.

1.2.Acromegaly

-          The head, hands and feet enlarged.

1.3.Pituitary Dwarfism

-          Insufficient secretion of somatotrophic hormone during the growth period of life, the subject may be only 4 feet tall.

2.      Thyroid Gland

2.1.Simple Goiter (Goitre)

-          An enlargement of the thyroid gland resulting from an inadequate supply of iodine in the diet.

2.2.Cretinism

-          Condition caused by an absence or undevelopment of the thyroid gland in infancy.

2.3.Myxodema

-          It may result from disease of the thyroid gland.

2.4.Hyperthyroidism / Grave’s Disease / Exophthalmic Goiter

-          Due to over secretion of the hormones of the thyroid gland.

3.      Parathyroid Gland

3.1.Hypoparathyroidism

-          A condition resulting from an insufficient secretion of the parathyroid hormone.

3.2.Hyperparathyroidism

-          Due to an excessive secretion of the parathyroid hormone from a tumor, etc.

4.      Suprarenal Glands

4.1.Addison’s Disease

-          Condition resulting from a decrease in hormones secreted by the vertex of suprarenal glands.

4.2.Cortical Tumors

-          May occur in the young or in the adult.

Muscular System

MUSCULAR SYSTEM

Classification of Muscles by Location

1.       Skeletal Muscles

-          Usually attached to bones

2.       Visceral Muscles

-          Located in the walls of some organs

3.       Cardiac Muscles

-          Located in the heart (Myocardium)

Functions of Muscles

1.       Skeletal muscles contract and cause movement.

2.       They maintain position (posture) in the upright and other positions of the body.

3.       They give support to joints by maintaining a partial state of contraction.

·         Origin of a muscle is its more fixed, less movable, attachment, usually its proximal end.

·         Insertion of muscle is its more movable end, usually its distal end.

Tendon/Sinew/Cord/Leader

-          A cordlike connective structure that extends from the end of a muscle to a bony attachment.

Aponeurosis

-          A sheet of fibrous connective tissue that is often attached at one end to a muscle, often a flat ligament or other muscle.

Tendon Sheath

-          A tunnel-like channel that surrounds a tendon.

Tenosynovitis

-          Inflammation of tendon sheath.

Bursa

-          Saclike structure lying between a muscle or tendon and an adjacent bony prominence over the muscle or tendon moves.

Bursitis

-          An inflammation of a bursa and it is frequently very painful.

Calcification

-          The deposition of calcium, may occur in bursa or tendon sheath, and may be demonstrated radiographically.

Muscle Tone

-          Muscles do not completely relax when at rest, but remain partly contracted.

Contraction

-          The main function of all muscles is to contract and cause movement of the body or part of it.

1.       Prime Movers

-          Muscles that initiate and carry out some movement, such as flexion of the forearm.

2.       Antagonists

-          Muscles that perform some movement opposite to that caused by prime movers.

3.       Synergists

-          Muscles that act with the prime movers to accomplish some movement but prevent unwanted movement.

4.       Fixation Muscles

-          Those that hold the adjacent bones in a fixed position so that the prime movers may accomplish some certain movement.

Posture

-          The maintenance of the upright position of the body consits of a balanced contraction of some muscle groups and the partial relaxation of opposing groups.

Muscle Spasm

-          A contraction of muscles that may persist for a long period of time, without relaxation.

Paralysis of Muscles

-          It follows injury or destruction of the nerves supplying that muscles.

Distribution of Muscles by Location

1.       Muscles of the Head:

-          Muscles of the eyelids

-          Muscles of the eyes

-          Muscles of the nose

-          Muscles of the mouth

-          Muscles of mastication (chewing)

2.       Muscles of the Neck

-          Superficail cervical muscles

-          Lateral cervical muscles

-          Suprahyoid, and infrahyoid muscles (anterior neck)

-          Anterior vertebral muscles

-          Lateral vertebral muscles

3.       Muscles of the Trunk

-          Deep muscles of the back

-          Suboccipital muscles

-          Muscles of the thorax

-          Muscles of the abdomen

o   Anterolateral

o   Posterior

-          Muscles of the pelvis

-          Muscles of the perineum

4.       Muscles of the Upper Limb / Member

-          Connecting the limb to the vertebral column

-          Connection of the upperlimb to the chest wall

-          Muscles of the shoulder

-          Muscles of the arm – brachial muscles

-          Muscles of the forearm – antebrachial

-          Muscles of the hand

5.       Muscles of the Lowerlimb / Member

-          Muscle of the iliac region

-          Muscles of the thigh

o   Anterior femoral muscles

o   Medial femoral

o   Gluteal muscles – buttocks

o   Posterior femoral

-          Muscles of the leg, crural muscles

o   Anterior crural

o   Posterior crural (superficial)deep

-          Muscles of the foot

o   Dorsal muscles of the foot

o   Plantar muscles of the foot (1^st,2^nd,3^rd,4^th layers)

The Head

-          These are responsible for movements of the eyelids, eyes, nose, mouth, jaws, and ears.

The Neck

-          Rounded cylindrical appearance of the neck is due to the muscles located here.

The Thorax

-          Several of the muscles of the anterior and posterior chest wall pass laterally to the shoulder girdle or upper arm.

The Abdomen

-          The posterior abdominal wall on each side of the vertebrae is formed by psoas major and quadratus lumborum muscles.

The Pelvis

-          The muscles of the pelvis form a sling across the floor of the pelvic cavity, with openings fro the anla, urinary and female passages.

The Perineum

-          Space between the two schial tuberosities, the pubic arch and coccyx is filled in by the perineal muscles.

The Upper Limb

-          Muscles extending from the chest wall to the shoulder girdle have been noted.

Shoulder Muscles

-          Pass over the shoulder to the humerus and are responsible for the movements of the upper humerus.

Muscles of the Forearm

-          The antebrachial muscles control movements of the wrist and hand.

The Lower Limb

-          Muscles connect the lower limb to the trunk.

The Thigh

-          Muscles that make up the thigh control movements at the knee.

Flexor Muscles of the Leg

-          Lie on the posterior surface of femur, not the anterior.

Extensor Muscles of the Leg (Anterior Femoral Muscles)

-          Lie anterior to the femur

The Leg

-          Muscles of the leg overlying the tibia and fibula control movements of the ankle and foot.

The Anterior Crural Muscles

-          In front of the tibia and fibula, and in tendons that cross the anterior surface of the ankle to insert into the upper surface of the bones of the foot.

The Posterior Crural Muscles

-          Muscles from a superficial and a deep layer posterior to the tibia and fibula.

The Foot

-          Short muscles lie on the dorsal and plantar surfaces of the foot.

Muscles that are Important in Radiography

1.       Diaphragm / Phren

-          A dome shaped muscular partition that separates the thorax and abdomen.

Three Large Openings in the Diaphragm

1.       Aortic Hiatus – through which the aorta enters the abdomen from the thorax.

2.       Esophageal Hiatus – through which the esophagus enters the abdomen.

3.       Oprning (Foramen) of the Inferior Vena Cava – through which this vein enters the thorax.

Phrenic Arteries

-          Superior and inferior, and right and left are branches of the aorta supplying the diaphragm with blood.

2.       Pectoris Major Muscle

-          A right and left, fan-shaped muscles that covers the upper anterior chest wall.

3.       Psoas Major Muscle

-          Lies lateral to the lumbar vertebrae in the posterior wall of the abdomen.

4.       Intercostal Muscle

-          Fill in the spaces between adjacent ribs, and their costal cartilages – the intercostal spaces.

Example of Skeletal Muscle

1.       Sternomastoid Muscle

-          Strap-shaped muscle that passes obliquely down the neck from the mastoid process to the upper sternum and medial part of the clavicle.

2.       Pectoralis Minor Muscle

-          Lies behind the pectoralis major muscle and extends from the anterior chest wall to the process of the scapula.

3.       Deltoid Muscle

-          Forms the rounded curved of the shoulder. It connects the humerus to the shoulder.

4.       Brachialis Muscle

-          Lies in front of the lower humerus, but behind the biceps muscle, which hides most of it.

5.       Biceps Brachii

-          Located in front of the humerus.

6.       Triceps Brachii

-          Has three at its upper end, where it originates from the scapula and humerus.

7.       Flexor Digitorum Profundus

-          The deep flexor of the digits.

8.       Extensor Digitorum

-          Lies on the lateral margin of the forearm whereas the flexors lie on the medial and anterior margins.

9.       Trapezius Muscle

-          Triangular in shape, the two togethr form a four sided figure, diamond-shaped on the posterior surface of the neck and thorax.

10.   Latissimus Dorsi Muscle

-          Each is triangular is shape and is located on the back of the lower thorax and abdomen.

11.   Sacrospinalis Muscle

-          Extend vertically from the occipital bone to the sacrum on either side of the spinous process of the vertebrae.

12.   Psoas Minor Muscle

-          Lies in front of the psoas major muscle of the same side.

13.   Gluteus Maximus Muscle

-          Forms most of the tissue mass of the buttock on either side.

14.   Quadriceps Femoris Mscle

-          Actually four sided muscles located anterior to the femur

15.   Biceps Femoris Muscle

-          Located posterior to the femur in the thigh.

16.   Gatrocnemius Muscle

-          Forms most of the mass of the calf muscles on the back of the leg.

Ligaments and Tendons

1.       Inguinal Ligament

-          Lies obliquely in the crease between the anterior surface of the upper thigh and the lower abdomen on each side.

2.       Patellar Ligament

-          Part of the quadriceps femoris tendon that extends from the apex of the patella to the tibial tuberosity.

3.       Ligamentum Teres / Ligamentum Capitis Femoris

-          Ligament of femoral head lies within the hip joint.

4.       Calcaneal Tendon / Tendo Achilles or Achilles Tendon

-          Extends down from the calf muscles to the tuberosity of the calcaneus, posterior to the ankle and heel.

Myofibril – main unit of muscular system

Claudification – limping muscle

Rigor Mortise – rigidity muscle

Charlie Horse – muscle strain

Kymography – examination for involuntary muscle

Gluteus maximus ­– largest muscle

Brevis – shortest muscle

Strapedius – smallest muscle

Sartorius – longest muscle

Latisimus Dorsi – swimmer’s muscle

Diaphragm – the breathing muscle

Massetter – chewing muscle

Orbicularis Oris – smile muscle

Arrector Pili – hair muscle