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MCAT - Biology > Chapter 10 - Homeostasis > Flashcards

Chapter 10 - Homeostasis Flashcards

1
Q

What are the 4 key functions of the Excretory System?

A
  1. Regulation of blood pressure
  2. Blood osmolarity
  3. Acid-base balance
  4. Removal of Nitrogenous Wastes
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2
Q

What is the main function of the Kidneys? Which other structures help them accomplish this function?

A

The kidney produces urine, which flows into the ureter at the renal pelvis; urine is collected in the bladder until it is excreted through the urethra.

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3
Q

What are the structures of the Kidney?

A

The kidney contains a cortex and a medulla, Each kidney has a hilium, which contains a renal artery, renal vein and ureter.

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4
Q

How does the Kidney’s portal system work (with the two capillary beds in series)?

A
  1. Blood from the renal artery flows into afferent arterioles, which form glomeruli in Bowman’s Capsule (the first capillary bed)
  2. Blood then flows through the efferent arteriole to the vasa recta (the second capillary bed), which surround the nephron, before leaving the kidney through the renal vein.
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5
Q

Describe the structure of the Bladder

A

The bladder has a muscular lining known as the detrusor muscle, which is under parasympathetic control. It also has two muscular sphincters.

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6
Q

What are the two muscular sphincters of the Bladder?

A

The Internal Urethral Sphincter and the External Urethral Sphincter

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7
Q

What does the Internal Urethral Sphincter consist of?

A

Consists of smooth muscle and is under involuntary (parasympathetic) control.

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8
Q

What does the External Urethral Sphincter consist of?

A

Consists of skeletal muscle and is under voluntary control.

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9
Q

What are the three solute movement processes of the kidney?

A
  1. Filtration
  2. Secretion
  3. Reabsorption
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10
Q

Describe Filtration

A

Filtration is the movement if solutes from blood to filtrate Bowman’s Capsule. The direction and the rate of the Filtration is determined by Starling Forces.

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11
Q

What do Straling Forces account for?

A

The hydrostatic and oncotic pressure differentials between the glomerulus and Bowman’s space.

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12
Q

Describe Secretion

A

Secretion is the movement of solutes from blood to filtrate anywhere other than Bowman’s capsule

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13
Q

Describe Reabsorption

A

Reabsorption is the movement of solutes from filtrate to blood.

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14
Q

List the 10 structures in the Excretory Pathway, from where the filtrate enters the nephron to the excretion of urine from the body.

A
  1. Bowman’s Space
  2. Proximal Convoluted Tubule
  3. Descending limb of the loop of Henle
  4. Ascending limb of the loop of Henle
  5. Distal Convoluted Tubule
  6. Collecting Duct
  7. Renal Pelvis
  8. Ureter
  9. Bladder
  10. Urethra
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15
Q

List the 6 vessels in the Renal Vascular Pathway, starting from the renal artery and ending at the renal vein

A
  1. Renal Artery
  2. Afferent arteriole
  3. Glomerulus
  4. Efferent arteriole
  5. Vasa Recta
  6. Renal Vein
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16
Q

What arm of the Nervous System is responsible for contraction of the detrusor muscle?

A

Parasympathetic Nervous System

17
Q

What are the 6 Segments of the Nephron?

A
  1. Bowman’s Capsule
  2. Proximal convoluted tubule
  3. Descending limb of the loop of Henle
  4. Ascending limb of the loop of Henle
  5. Distal convoluted tubule
  6. Collecting duct
18
Q

What is the major function of Bowman’s Capsule?

A

It’s the site of filtration, through which water, ions, amino acids, vitamins, and glucose pass (essentially everything besides cells and proteins).

19
Q

What is the major function of the Proximal Convoluted Tubule?

A

It controls solute identity, reabsorbing vitamins, amino acids, and glucose, while secreting potassium and hydrogen ions, ammonia, and urea.

20
Q

What is the major function of the Descending Limb of the Loop of Henle?

A

It’s important for water reabsorption, and uses the medullary concentration gradient.

21
Q

What is the major function of the Ascending Limb of the Loop of Henle?

A

It’s important for salt reabsorption and dilution of the urine in the diluting segment.

22
Q

What is the major function of the Distal Convoluted Tubule?

A

Like the PCT, is important for solute identity by reabsorbing salts while secreting potassium and hydrogen ions, ammonia, and urea.

23
Q

What is the major function of the Collecting Duct?

A

It’s important for urine concentration; its variable permeability allows water to be reabsorbed based on the needs of the body.

24
Q

How can the kidney regulate pH?

A

By selective reabsorption or secretion of bicarbonate or hydrogen ions.

25
Q

What two hormonal systems are activated when blood pressure (and volume) are low?

A

Aldosterone and Antidiuretic Hormone (ADH or Vasopressin).

26
Q

How do ADH and Aldosterone differ in function in the context of blood pressure regulation?

A

ADH only governs water reabsorption and thus results in a lower blood osmolarity. Aldosterone causes both salt and water reabsorption and does not change blood osmolarity.

27
Q

What is the role of the Skin?

A

The skin acts as a barrier, protecting us from the elements and invasion by pathogens.

28
Q

What are the three major Skin layers?

A
  1. The Hypodermis (subcateneous layer)
  2. Dermis
  3. Epidermis
29
Q

What are the five layers of the Epidermis from deep to superficial?

A
  1. The Stratum Basale
  2. Stratum Spinosum
  3. Stratum Granulosum
  4. Stratum Lucidum
  5. Stratum Corneum
30
Q

What is the predominant cell type in the Epidermis?

A

Keratinocytes

31
Q

How are Keratinocytes formed?

A

The Stratum Basale contains stem cells that proliferate to form Keratinocytes. Keratinocyte nuclei are lost in the Stratum Granulosum, and many thin layers form in the Strartum Corneum.

32
Q

What are Melanocytes?

A

Melanocytes produce melanin, which protects the skin from DNA damage caused by ultraviolet radiation; melanin is passed to Keratinocytes.

33
Q

What are Langerhans Cells?

A

Langerhans Cells are specific macrophages that serve as antigen presenting cells in the skin.

34
Q

What are the two layers of the Dermis, from superficial to deep?

A

The Papillary Layer and the Reticular Layer

35
Q

What are 5 key sensory cells located in the dermis?

A
  1. Merkel Cells (deep pressure and texture)
  2. Free Nerve Endings (pain)
  3. Meissner’s Corpuscles (light touch)
  4. Ruffini Endings (stretch)
  5. Pacinian Corpuscles (deep pressure and vibration)
36
Q

What does the Hypodermis contain?

A

Contains fat and connective tissue and connects the skin to the rest of the body.

37
Q

Define Thermoregulation

A

The maintenance of a constant internal temperature

38
Q

What are the body’s 2 cooling mechanisms?

A
  1. Sweating; draws heat from the body through evaporation of water from sweat
  2. Vasodilation; sweat glands are innervated by postganglionic cholinergic (sympathetic neurons)/
39
Q

What are the body’s 3 warming mechanisms?

A
  1. Piloerection; arrestor pili muscles contract, causing hairs to stand on end (traps warmth)
  2. Vasoconstriction (shivering)
  3. Insulation (provided by fat)

MCAT - Biology (12 decks)

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