Urinary bladder

Question 1

what is teh bladder and where is it

Answer 1

The bladder is an organ of the urinary system, situated anteriorly in the pelvic cavity. It is hollow, highly distensible, and rounded in shape.

Question 2

main function of the bloaddr

Answer 2

The main function of the bladder is the collection, temporary storage, and expulsion of urine. It has a unique muscular structure, and a complex neurological control, which shall be considered in detail.

Question 3

embryological derivite of the bladder

Answer 3

hind gut

Question 4

fundtins of the bladder

Answer 4

The bladder largely serves two functions:

Temporary store of urine – The bladder is a hollow organ. The walls are very distensible, with a folded internal lining (known as rugae), this allows it to hold up to 600ml.
Assists in the expulsion of urine – During voiding, the musculature of the bladder contracts, and the sphincters relax.

Question 5

shape of teh urinary bladder

Answer 5

The morphological appearance of the bladder varies with filling. When full, it exhibits an oval shape, and when empty it is flattened by the overlying intestines.

The important external features are the apex, body, fundus and neck:

The external anatomical features of the bladder
Apex – This is located superiorly, pointing towards the pubic symphysis. It is connected to the umbilicus by the median umbilical ligament (a remnant of the urachus).

Body – The main part of the bladder, located between the apex and the fundus
Fundus (or base) – Located posteriorly. It is triangular-shaped, with the tip of the triangle pointing backwards.
Neck – Formed by the convergence of the fundus and the two inferolateral surfaces. This structure joins the bladder to the urethra.
Urine enters the bladder by the left and right ureters, and exits via the urethra. Internally, these orifices are marked by the e trigone – a triangular area located within the fundus. In contrast to the rest of the internal bladder, the trigone has smooth walls.

There are two sphincters controlling the outflow of urine; the internal and external urethral sphincters.

Question 6

desribe the bladder stretch reflex

Answer 6

The bladder stretch reflex is a primitive spinal reflex, in which micturition is stimulated in response to stretch. It is analogous to a muscle spinal reflex, such as the patella reflex.

During toilet training in infants, this spinal reflex is overridden by the higher centers of the brain, to give voluntary control over micturition.

The reflex arc:

Bladder fills with urine, and the bladder walls stretch. Sensory nerves detect stretch and transmit this information to the spinal cord.
Interneurons within the spinal cord relay the signal to the parasympathetic efferents (the pelvic nerve).
The pelvic nerve acts to contract the detrusor muscle, and stimulate micturition.
Although it is non-functional post childhood, the bladder stretch reflex needs to be considered in spinal injuries (where the descending inhibition cannot reach the bladder), and in neurodegenerative diseases (where the brain is unable to generate inhibition).