Question

1. The testicles are kept cooler than normal body temperature. Name the structures that are involved
with this & describe how they accomplish this.
2. What organs are considered to be secondarily retroperitoneal?

Answer 1

Question 1.

Testes are a pair of male gonads located outside the body within a pouch of skin called as scr*tum. Spermatogenesis and testosterone production are two main functions of the testes. To carry out these functions, the ideal temperature required is 4 degrees to 5 degrees celcius lower than the normal body temperature. Thus, the testes function normally at around 32-33 degrees celcius.

The structures that are involved in lowering the temperature of the testes are tunica dartos muscle layer of scr*tum, cremaster muscle of spermatic cord, pampiniform plexus of veins and sweat glands over the scr*tum

Tunica dartos is a smooth muscle layer within the scr*tum which contracts during the cold weather, wrinkling the scr*tal surface thereby decreasing the surface area and hence the heat loss is decreased thus the temperature is slightly increased inside the scr*tum than the outside cold weather making it optimum for the functions of the testes. Also, the cremaster muscle of the spermatic cord contracts bringing the testes closer to the abdominal cavity thus maintaing slightly higher temperature than the outside colder environment.

During warm and hot weather, the tunica dartos muscle layer of the scr*tum, relaxes which increases the scr*tal surface area causing more heat loss thus lowering down the temperature of the scr*tum as compared to the outside hot weather helping in maintaing the optimum temperature level for testicular functions. Also, during hot weather, the cremaster muscle of spermatic cord relaxes, which brings the testes lower down into the scr*tum away from the abdominal cavity which again helps in bringing down the scrotal temperature to optimum level.

The testes are surrounded by a network of venous plexus known as pampiniform plexus of veins which redirects the heat of the warm arterial blood into the venous system by counter-current heat exchange thereby maintaining the optimum temperature for testicular functions.

The scrotal skin is supplied by alot of large sweat glands which also helps in regulating the scrotal temperature by sweating and keeping the scrotal surface cool when required.

Question 2.

A tissue membrane which lines the abdominal cavity and supports and surrounds the abdominal organs is known as peritoneum.

Retroperitoneal organs are those organs which lie behind the peritoneum is association with the posterior abdominal wall. They are of two types :- primary retroperitoneal organs and secondary retroperitoneal organs.

Primary retroperitoneal organs are those organs which lie behind the peritoneum all along the embryonic life of an individual as well as during the adult life.

Examples of primary retroperitoneal organs are :-

- inferior cava

- aorta

- ureters

- kidneys

- adrenal glands.

Secondary retroperitoneal organs are those organs which were located inside the mesentery (part of the peritoneum which connects the intestine to the posterior abdominal cavity) during the embryonic life but later they migrated behind the peritoneum during the adult life.

Examples of secondary peritoneal organs:-

- the head, neck and body of the pancreas (tail is intraperitoneal)

- the ascending and descending colon

- the duodenum (except the first part which is intraperitoneal).