Urinary Tract and Water Balance

Flashcards about the lower urinary tract structure-function

What are the components of the lower urinary tract?

The lower urinary tract includes the urinary bladder and pelvic urethra.

What is the function of the detrusor muscle?

The detrusor muscle expels urine following parasympathetic activation via pelvic nerve innervation.

What are the components of the lower urinary tract?

The lower urinary tract includes the urinary bladder and pelvic urethra.

What is the function of the detrusor muscle?

The detrusor muscle expels urine following parasympathetic activation via pelvic nerve innervation.

What is the function of the smooth muscle sphincter in the urinary tract?

The smooth muscle sphincter provides involuntary tonic resistance when activated by sympathetic innervation via hypogastric nerves, also inhibiting detrusor activity.

What innervates the striated urethralis muscle, and what is its function?

The pudendal nerve innervates the striated urethralis muscle, which opposes sudden increases in bladder pressure and is employed for voluntary continence.

What are the basic layers of the organs in the lower urinary tract?

The basic layers are the urothelium, the suburothelial layer, the detrusor muscle, and the serosa.

What is the urothelium?

An innermost lining composed of transitional cell epithelium providing an elastic barrier that is impermeable to urine and has a high metabolic rate and an important role in controlling bladder function.

What is the function of the suburothelial layer?

It lies immediately beneath the urothelium, is highly active metabolically, and acts in concert with the urothelium to subserve a key afferent role.

What are umbrella cells?

Superficial cells that form a dome-shaped structure at the apical pole and can cover multiple underlying intermediate cells.

What is the glycocalyx?

A dense, gel-like meshwork that forms a physical barrier at the apical membrane of the umbrella cell layer.

What is the importance of the urothelial barrier function?

Maintaining a high-resistance barrier to the outside environment for prolonged periods, preventing the diffusion of harmful urinary products into underlying tissues, and defending against pathogens.

What are slow waves in visceral smooth muscle?

Spontaneous rhythmical undulations of the resting membrane potential around a baseline, generated by specialized smooth muscle cells (Cajal).

What is the role of stretch receptors in the bladder during filling?

Sending afferent signals along the pelvic nerve, which activate a reflex arc through the hypogastric nerve to the urethra.

What neurotransmitter is released during bladder filling, and what receptors does it activate?

Norepinephrine (NE), activating beta(3)-adrenergic receptors in the bladder wall and alpha1-adrenergic receptors in the urethra.

What neurotransmitter is released during micturition, and what receptors does it activate?

Acetylcholine (ACh), binding to Muscarinic (M3) receptors and stimulating bladder smooth muscle contraction.

What is the likely outcome of damage to the pudendal nerve in relation to urinary control?

Loss of voluntary control over the external urethral sphincter, causing urinary incontinence

What are the two main categories of urinary incontinence (UI)?

Disorders of storage and disorders of voiding.

What is the most common functional urine storage disorder in dogs?

Urethral sphincter mechanism incompetence.

What characterizes disorders of voiding?

UI with a larger postvoiding residual volume (PVRV) with or without secondary overflow UI.

What is the most common cause of urinary incontinence in dogs?

Urethral sphincter mechanism incompetence