Physiology - Week 9 - Urinary & Reproductive Systems

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Questions and Answers

What is the primary function of the renal pyramids?

To collect urine (correct)

To store urine

To produce urine

To filter blood

How do nephrons contribute to urine formation?

By filtering large proteins from blood

By directly excreting urine into the renal pelvis

By recovering chemicals the body needs and removing waste (correct)

By maintaining blood pressure

What components are included in the filtrate that flows through the nephron?

Hormones and vitamins

Urea and glucose (correct)

Large proteins and red blood cells

Only water and electrolytes

What is a key characteristic of urge incontinence?

Loss of urine triggered by certain stimuli. Signup and view all the answers

What is the normal range for glomerular filtration rate (GFR)?

120-125 ml/min Signup and view all the answers

Which structure surrounds the glomerulus and plays a key role in filtration?

Bowman's capsule Signup and view all the answers

Which hormone is primarily responsible for sodium reabsorption in the kidneys?

Aldosterone Signup and view all the answers

What is the main effect of Antidiuretic Hormone (ADH) on the kidneys?

Increases water reabsorption from filtrate. Signup and view all the answers

Which hormone is released in response to elevated blood pressure and promotes sodium and water excretion?

Atrial Natriuretic Peptide (ANP) Signup and view all the answers

What best describes the function of the juxtaglomerular cells?

Release renin when blood flow to the glomerulus declines. Signup and view all the answers

Which of the following is a correct description of meiosis?

Involves nuclear division exclusively in the gonads. Signup and view all the answers

What process is characterized by the conversion of angiotensinogen to angiotensin I?

Release of renin by juxtaglomerular cells. Signup and view all the answers

Which structure produces female gametes?

Ovaries Signup and view all the answers

What is the main function of the ureters in the urinary system?

Transport urine from kidneys to bladder Signup and view all the answers

Which hormone produced by the kidneys helps in regulating blood pressure?

Renin Signup and view all the answers

Which part of the kidney is responsible for urine formation?

Renal Medulla Signup and view all the answers

What is the role of erythropoietin in the body?

To stimulate bone marrow to produce red blood cells Signup and view all the answers

The kidneys are primarily located between which vertebrae?

T12-L3 Signup and view all the answers

Which component of the urinary system is responsible for excreting urine from the bladder to the outside of the body?

Urethra Signup and view all the answers

Which function does the urinary system NOT perform?

Produces digestive enzymes Signup and view all the answers

What anatomical structure acts as an outer cover to prevent infections in the kidney?

Renal Capsule Signup and view all the answers

What is the primary purpose of crossing over during meiosis?

To exchange DNA between non-sister chromatids Signup and view all the answers

What is the primary purpose of maintaining the acid-base balance in body fluids?

To support metabolic reactions Signup and view all the answers

Which of the following statements accurately describes the sex chromosomes in humans?

The Y chromosome is present only in males Signup and view all the answers

Which of the following does NOT describe the kidneys?

They produce bile. Signup and view all the answers

How many haploid cells are produced at the end of meiosis?

4 haploid cells Signup and view all the answers

What characterizes the primary oocyte in females during meiosis?

It is arrested in prophase I before birth. Signup and view all the answers

In comparison to mitosis, meiosis involves how many nuclear divisions?

Two nuclear divisions Signup and view all the answers

Which part of the spermatozoon is responsible for propelling it forward?

Tail (flagellum) Signup and view all the answers

During what phase does the secondary oocyte undergo division if sperm is present?

Meiosis II Signup and view all the answers

What type of cells are produced by meiosis?

Haploid gametes Signup and view all the answers

What is the role of the mitochondria in sperm cells?

To produce ATP for propulsion Signup and view all the answers

What is NOT a characteristic of meiosis when compared to mitosis?

Produces genetically identical cells Signup and view all the answers

What is the main function of the proximal convoluted tubule in the nephron?

Reabsorbing water and solutes from filtrate Signup and view all the answers

Which structure of the nephron is primarily responsible for the concentration of urine?

Collecting duct Signup and view all the answers

What is the role of the juxtaglomerular apparatus in kidney function?

It regulates blood pressure and filtration rate. Signup and view all the answers

During which process is glucose primarily reabsorbed back into the blood from the nephron?

Reabsorption Signup and view all the answers

In which part of the nephron does secretion of ions and waste products primarily occur?

Distal convoluted tubule Signup and view all the answers

What are the correct order of structures that filtrate passes through after leaving the glomerulus?

Proximal convoluted tubule, nephron loop, collecting duct Signup and view all the answers

What is primarily filtered from the blood into the Bowman’s capsule?

Cell- and protein-free filtrate Signup and view all the answers

Where does urine formation start in the nephron?

Glomerulus Signup and view all the answers

Which part of the renal system collects urine from multiple nephrons?

Collecting duct Signup and view all the answers

What do we call the process of moving substances from the blood into the nephron tubule?

Secretion Signup and view all the answers

Study Notes

Urinary System: Fox Chapter 17

Objectives include listing the urinary system's components and understanding its functions. Describing the filtrate pathway in the nephron is also an objective.
The main components of the urinary system are kidneys, ureters, bladder, and urethra. The kidneys produce urine, ureters transport it, the bladder stores urine, and the urethra excretes it.
Kidneys are located between the 12th rib and L3 vertebrae. The right kidney sits slightly lower than the left kidney due to the liver's position.
Kidney functions include excretion (removing metabolic waste and toxins), maintaining acid-base balance, regulating blood pressure, red blood cell production, and blood glucose regulation.
Ureters are long, slender muscular tubes that transport urine from the kidneys to the bladder via gravity and peristalsis.

Anatomy of a Kidney

The kidney's outer layer is the renal capsule, which protects from infections. The renal cortex is the outer portion and the medulla contains tubes responsible for urine formation.
Renal pyramids are cone-shaped structures within the medulla. Renal pelvis collects urine from the pyramids' tips.
Calyces (singular: calyx) are extensions of the renal pelvis. They collect urine from the pyramids and move it to the renal pelvis.

Nephrons

Nephrons are the structural and functional units of the kidneys. There are over one million per kidney.
Nephrons create filtrate from blood, recover needed chemicals, and secrete waste into the filtrate, which becomes urine.
Nephrons' components are Bowman's capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule, and the collecting duct (multiple nephrons share a collecting duct).

Filtrate

Filtrate, flowing through the nephron, should not contain large proteins or red blood cells which is a normal condition.
It's composed of water, salts, glucose, amino acids, creatine, and other substances.

Renal Tubule

The renal tubule is the part of the nephron where filtrate moves before entering the collecting duct.
The three parts of the renal tubule are the proximal convoluted tubule, nephron loop, and distal convoluted tubule.

Juxtaglomerular Apparatus

The juxtaglomerular apparatus is where the distal convoluted tubule meets the afferent arteriole and contains specialized cells that regulate blood pressure.

Processes of Urine Formation

Urine formation has four main processes: glomerular filtration, reabsorption, secretion, and excretion
Glomerular filtration filters the blood in the Bowman's capsule. Reabsorption takes materials out of the filtrate and puts them back in the blood. The third step, secretion, transfers materials from the blood to the filtrate. Excretion removes urine from the body.

Pathway of Filtrate

The pathway if filtrate begins with the afferent arteriole. Filtrate travels through Bowman's capsule, proximal convoluted tubule, nephron loop, distal convoluted tubule, collecting duct, calyx, renal pelvis, ureter, urinary bladder, and urethra.

Counter-Current Multiplier in the Loop of Henle

The loop of Henle's descending limb is permeable to water, reabsorbing it back into the bloodstream.
The ascending limb is impermeable to water but actively transports sodium, chloride, and potassium out of the filtrate and into the blood. This process creates a concentration gradient for water reabsorption in the loop.

Overall Reabsorption and Secretion in the Nephron

The blue parts of a diagram represent reabsorption, taking substances from the filtrate and putting them back into the blood.
The green parts of a diagram represent secretion, moving substances from the blood to the filtrate.

What Urine is Composed Of

Urine is mostly water (95%).
Other components include urea, uric acid, and creatine .

The Urinary Bladder

The bladder is a temporary urine storage organ. It has multiple layers, including a mucous membrane, transitional epithelium (allows the wall to stretch), rugae (folds), and a three-layered coat of involuntary muscle tissue.

The Urethra

The urethra is a tube for excreting urine from the bladder. It consists of multiple layers. A mucous membrane helps it stretch, and rugae - or folds- provide more room to stretch. A three-layered coat helps with involuntary muscle tissue.

Excretion

Excretion: Urination (voiding) takes place as urine travels from renal tubules to the collecting duct to the renal calyx to the pelvis to the bladder (for storage) to the urethra.

Physiology of Micturition

Bladder storage happens constantly at about 400-600 ml capacity, and accommodates filling. Sensory stretch receptors first detect filling, then the guarding reflex of the external sphincter occurs as the bladder fills further.
For voiding the stretch receptors produce a strong sensation. This triggers relaxation of the PFM and internal sphincter. The detrusor muscle contracts, and urination occurs when outlet pressure is less than bladder pressure.

Normal Bladder Health

An average healthy person urinates 5-7 times in a day with 8-12 oz urine output each time.
The average time interval between voiding is 2-3 hours.
Normally, a person under 65 urinates 0 times at night and 1-2 times for people over 65.

Types of Urinary Incontinence

Incontinence is the involuntary loss of urine, which isn't normal. Common types include stress, urge, mixed, and functional incontinence, as well as neurogenic bladder.

Hormonal Regulation in the Nephrons

Parathyroid hormone (PTH) is secreted from parathyroid glands. It mainly acts in the distal convoluted tubule (DCT) to increase calcium reabsorption into the body.
Antidiuretic hormone (ADH) is produced by the hypothalamus and released by the posterior pituitary gland. It is released in response to high blood solute concentration or low blood volume.
ADH targets the kidneys to increase water reabsorption. It works by inserting aquaporins in the collecting duct cells, which increases water's permeability, so more water is reabsorbed back into the blood.

Sodium Regulation

Sodium (Na+) is the primary extracellular solute. It's crucial for osmotic pressure and excitable cell function.
Distal convoluted tubule and collecting duct principal cells regulate Na+ reabsorption, and hormones ADH and aldosterone assist in this process.
Atrial natriuretic peptide (ANP) helps reduce blood pressure and blood volume by inhibiting sodium and water retention.

Potassium Balance

Potassium balance is controlled by how much of potassium is filtered, how much is reabsorbed, and if any is secreted. Aldosterone is secreted in response to elevated potassium levels and will increase the excretion (or output) of potassium from the body.

Reproductive System: Fox Chapter 20

Objectives include listing male and female gonads, understanding meiosis, explaining genetic diversity, comparing mitosis and meiosis, and explaining sperm and ova structural differences.
The male gonads are the testes, and the female gonads are the ovaries.
Both testes and ovaries produce gametes (sperm and ova or egg cells) that have half the genetic information of the parent.

Review of General Hypothalamic and Anterior Pituitary Control

Gonadotropin-releasing hormone (GnRH) and other hormones control releases of FSH and LH in the testes and ovaries, and regulate the production and secretion of reproductive hormones and gametes.

Meiosis

Meiosis is a type of nuclear division that produces gametes.
Key differences between mitosis and meiosis include: meiosis produces four haploid cells, whereas mitosis produces two identical diploid cells; meiosis involves crossing over (exchange of genetic material between homologous chromosomes), which doesn't occur in mitosis.

Chromosomes

Humans have 46 chromosomes (23 pairs), with 2 of the pairs being sex chromosomes.
Autosomes are the 22 pairs of chromosomes that aren't sex chromosomes.

Meiosis in Females

Meiosis I occurs before ovulation, creating a primary oocyte that is arrested in prophase I until fertilization, then it becomes a secondary oocyte.
Meiosis II is completed if sperm fertilizes the secondary oocyte, otherwise it is released.

Sperm Cell

Sperm cells have a head, midpiece, and tail. The head contains the nucleus and acrosome for digesting barriers. The midpiece has mitochondria, for energy ATP generation. The tail is for movement.

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Description

This quiz covers the key components and functions of the urinary system, as outlined in Fox Chapter 17. It includes details about the nephron's filtrate pathway and the kidneys' role in excretion and regulation. Test your understanding of the anatomy and physiology involved in urine production and transport.