Urogenital system

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Disposition and origin53

9.2 Urinary tract53
9.3 Reproductive tract53
Overview
The urinary and genital components of the urogenital system are derived from common embryological sources. Their functions are at first sight dissimilar: the urinary system is mainly for excretion of waste products from the blood stream, and the genital system for reproduction. In mammals, organs of both systems are confined to the lower abdomen, pelvis and perineum.
Learning Objectives
You should:

• list the main organs making up both systems
• describe the common origin and shared anatomy.

9.1. Disposition and origin

The urogenital system is confined in mammals to the abdomen, pelvis and perineum. The two components, urinary and genital, have a common embryological origin.

• The gonads and kidneys (and adrenal cortex) are from embryonic tissue on the posterior coelomic wall (the coelom is in the early embryo what will, in this region, become the abdominal cavity). This common origin is reflected, despite subsequent movements during development, in the blood supply, lymph drainage and, for the adrenal cortex and the gonads, the secretion of steroid hormones.
• Much of the duct systems of the urogenital organs originate with the terminal portion of the gut: they are either cloacal derivatives, or they open into the cloaca (Latin: sewer). These structures include:

– in both sexes, the urethra, bladder, ureters, collecting ducts of the kidney
– in the female, the vagina, uterus and Fallopian tube
– in the male, the ductus (vas) deferens and seminal vesicles.

9.2. Urinary tract (Fig. 9.1)

Urine is produced in the right and left kidneys and passes through the right and left ureters to the bladder. It is expelled from the bladder through the (midline) urethra. This is short in the female and longer in the male, traversing the penis.

9.3. Reproductive tract

Male reproductive organs (Fig. 9.2)

The paired testes develop high on the posterior body wall and before birth descend to the scrotum. Spermatozoa are produced in the testis and at ejaculation are propelled along the ductus (vas) deferens on each side to join the (midline) urethra in the substance of the prostate gland. They travel to the tip of the penis in the urethra.

Female reproductive organs (Fig. 9.3)

The ovaries also develop high on the posterior body wall but do not descend as far as the testis so that the ovaries remain in the lower abdominal cavity. The uterus and Fallopian (uterine) tubes develop from a paired tubular system that partially unites. Those parts which remain paired are the Fallopian tubes; those that unite form the uterus in which the fetus develops, and the vagina which receives the penis at copulation and through which the baby is born.

Self-assessment on Section 1 (Chapter 1, Chapter 2, Chapter 3, Chapter 4, Chapter 5, Chapter 6, Chapter 7 and Chapter 8)

True/false questions

Each lettered option is either true or false.

1. Concerning anatomical nomenclature:

a. medial means in the midline of the body.
b. inferior means smaller than superior.
c. a coronal section divides a structure into a right portion and a left portion.
d. sensory nerve impulses pass towards the central nervous system.
e. the autonomic nervous system supplies smooth muscle.
2. Concerning ribs and sternum:

a. typical ribs articulate with vertebrae at the head and at the tubercle.
b. the first costosternal joint is synovial.
c. hyaline cartilage is found between the anterior end of a typical rib and the sternum.
d. the upper part of the sternum is the manubrium.
e. the fourth rib articulates with the sternum at the sternal angle of Louis.
3. Synovial joints are present:

a. between costal cartilages and the sternum.
b. between articular processes of vertebrae.
c. between adjacent vertebral bodies.
d. between the two pubic bones.
e. between the head of a rib and the vertebral column.
4. The epiphyseal plate:

a. is at the junction of the head and the shaft of a developing long bone.
b. is the site of growth in length.
c. is present in a mature bone.
d. is composed of hyaline cartilage.
e. prevents arteries passing from the shaft to the head of the bone.
5. Concerning the meninges and meningeal spaces:

a. the pia mater is prolonged below the spinal cord as the cauda equina.
b. the dural sac ends below at vertebral level S2.
c. the spinal extradural space contains adipose tissue and a plexus of veins.
d. the pia mater is firmly adherent to the spinal cord.
e. the arachnoid mater is outside the dura mater.
6. Blood from the following veins reaches the heart in the superior vena cava:

a. subclavian veins.
b. internal jugular veins.
c. hepatic veins.
d. veins of the upper thoracic wall.
e. femoral veins.
7. Upper limb arteries include:

a. axillary.
b. brachial.
c. popliteal.
d. radial.
e. dorsalis pedis.
8. Concerning lumbar puncture and the vertebral column:

a. at lumbar puncture, a needle inserted between the laminae of adjacent vertebrae will penetrate the ligamentum flavum.
b. lumbar puncture is normally performed between vertebrae L1/2 in an adult.
c. during lumbar puncture, cerebrospinal fluid is taken from the subdural space.
d. the posterior longitudinal ligament forms part of the anterior wall of the vertebral canal.
e. venous blood from a vertebral body drains to the internal vertebral venous plexus.
9. In the spinal cord:

a. grey matter consists of collections of myelinated axons.
b. myelin is manufactured in peripheral nerves by Schwann cells.
c. disease of the ventral horn cells would result in paralysis or weakness of skeletal muscle.
d. the lateral horn of grey matter is concerned with the innervation of smooth muscle.
e. the dorsal column of white matter is concerned with sensory perception.

Single best answer questions

Questions 10–25

10. In the anatomical position, the palms of the hands face:

a. anteriorly.
b. inferiorly.
c. posteriorly.
d. superiorly.
11. Straightening the upper limb at the elbow joint is

a. abduction.
b. adduction.
c. extension.
d. flexion.
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