Homeostasis

Question 1

List major Functions of the kidney.

Answer 1

Overall Function: Maintain Homeostasis

1. Regulates:
   
   1. Blood Pressure/Volume
   2. Osmolarity
   3. Acid-Base Balance (pH balance)
   4. Filtration: removal of nitrogenous (and other) waste

Question 2

What are the adrenal cortex, adrenal medulla, and hilum of the kidney?

Answer 2

1. Cortex: outer layer
2. Medulla: Inner portion
3. Hilum
   
   1. Contains Renal:
      
      1. Artery
      2. Vein
      3. Ureter

Question 4

What is the renal portal system and what does it contain?

Answer 4

Two capillary beds in series with each other that blood must travel through before returning to the heart.

1. Blood renal artery and first travels through the afferent arteriole, which forms into the glomerulus (1st capillary bed)
2. Blood secondly travels through the efferent arteriole to the peritubular capillaries

Question 5

Vasa Recta

Answer 5

Two capillary beds within the renal portal system that surround the loop of henle.

Question 6

What is the functional unit of the kidney and what are its major structures?

Answer 6

Nephron

1. Glomerulus/Bowman’s Capsule
2. Proximal Convoluted Tube
3. Loop of Henle
4. Distal Convoluted Tube
5. Collecting Duct

Question 7

Explain the “story” of blood/filtrate that passes through the kidney.

Answer 7

1. Blood Flows into the kidney via the renal artery.
2. Renal artery ► Afferent Arteriole ► Glomerulus
3. Glomerulus
   
   1. Blood, under high hydrostatic pressure from the renal artery, passes through this very leaky, fenestrated “ball” capillaries.
   2. Fenestrations allow for large particles to flow out of the bloodstream, except for larger proteins such as blood platelets or albumins.
   3. Nutrients and waste flow out of the blood into the bowman’s capsule surrounding the glomerulus.
4. Bowman’s Capsule
   
   1. “Captures” waste and nutrients that leaked out of the glomerulus.
5. Proximal Convoluted Tube (active transport)
   
   1. Reabsorption of nutrients up to a certain point via microvilli (to maintain homeostasis)
      
      1. Thus helps regulate solute concentrations within body and surplus is urinated.
   2. Becomes more/less efficient at retrieval based on levels within the body.
6. Loop of Henle
   
   1. Retrieves H2O and salt
      
      1. As you move down and get closer to the inner portion of the kidney, salt concetration increases
   2. Ascending Loop
      
      1. Permeable to H2O
   3. Descending Loop
      
      1. Permeable to Salt
7. Distal Convoluted Tube
   
   1. Retrieves more nutrients
   2. Responsive to Aldosterone for salt reapsorption
   3. Takes more nitrogenous waste from peri-capillary tubes and puts it into filtrate
8. Collecting Duct
   
   1. Last to retreive more H2O
   2. Regulated by ADH and Aldosterone for reabsorption as needed.
   3. Becomes less or more permeable to H2O, as regulated by hormones states above.
9. Urine is collected by renal pelvis and dumped into ureter.
10. Urine moves down ureter and is stored in bladder and excreted via the urethra.

Question 8

Movement of solutes from blood to filtrate at Bowman’s capsule.

Answer 8

Filtration (direction and rate is determined by starling forces)

Question 9

Movement of solutes from blood to filtrate anywhere else except Bowman’s capsule.

Answer 9

Secretion

Question 10

Movements of solutes from filtrate to blood.

Answer 10

Reabsorption

Question 11

How is micturition controlled?

Answer 11

Via internal urethral sphincter and external urethral sphincter

1. Internal Urethral Sphincter
   
   1. Smooth muscles (involuntary/parasympathetic control)
2. External Urethral Sphincter
   
   1. Skeletal Muscle (voluntary/sympathetic control)

Question 12

What is the countercurrent multiplier system and why is it important?

Answer 12

1. Flow of blood in the vasa recta and flow of filtrate in the loop of henle move in opposition to one another.
2. This is important because if they flowed in the same direction, they would reach equilibrium quicker and the kidney would not be able to absorp as much water.
   
   1. In the loop of henle, the filtrate is being exposed to hypertonic urine, which maximizes absorption of H2O (opposite occurs)

Question 13

What is reabsorped and secreted in the the PCT? What type of transport is used to secrete these molecules?

Answer 13

1. Active Transport Proteins Reabsorb:
   
   1. Glucose
   2. Proteins
   3. Other Solutes
2. Antiport system is used to secrete:
   
   1. Na+ and H+ (although they move in different directions)
   2. Driven by sodium concentration gradient
3. Alos secretes
   
   1. K+, Ammonia, and urea

Question 14

What is the diluting segment?

Answer 14

Part of the ascending loop of henle that is filled with mitochondria that dilute the urine (important during overhydration)

Question 15

What are the mean solutes the DCT reabsorp? secrete?

Answer 15

1. Reabsorb: Na+ and Ca+
2. Secrete: K+, H+, HCO3

Question 16

What is aldosterone release in response to and what structures and enzymes contributes to to the release of this hormone?

Answer 16

1. Responds to low BP
   
   1. Juxtaglomerular cells are sensitive to filtrate pressure and release Renin in reponse to low pressure
   2. Renin cleaves angiotensinogen to for A1
   3. A1 travels to the lungs and is converted to A2 via ACE (angiotensin converting enzyme)
   4. A2 travels back to the kidney to trigger the release of Aldosterone from the adrenal cortex

Question 17

How does the kidney work to maintain blood pH (in addition to respiratory system)

Answer 17

Through selective increase/decrease of secretion of

1) H+ Ions
2) HCO3

Question 18

The purpose of aldosterone is to increase absorption of ____ while promoting excretion og ____ and ____.

Answer 18

1. Na+
2. H+ ions
3. K+ Ions

Question 19

Come Let’s Get Sun Burned!

Answer 19

5 strata of the skin with Epidermis (Superficial to Deep):

1. Corneum
2. Lucidum
3. Granulosum
4. Spinosum
5. Basale

Question 20

List the functions of the skin strata in order from deepest two superificial.

Answer 20

1. Basale
   
   1. Contains stem cells responsible for proliferation of keratinocytes (produce Keratine)
2. Spinosum
   
   1. Skin cells begin connecting together
3. Granulosum
   
   1. Keratinocytes die and lose their nuclei
4. Lucidum
   
   1. Only present in thick, hairless parts of the body (soles and palms)
5. Corneum
   
   1. Several layers of flat (dead) keratinocytes
   2. Forms barrier from inner layers to prevent invasion of pathogens or loss of fluids

Question 21

______ produce melanin. What is the main purpose of melanin?

Answer 21

1. Melanocytes
2. Purpose:
   
   1. Protect skin from DNA damage caused bu UV radiation.
   2. Passed down to keratinocytes.
   3. Darker skin complexions have more active melanocytes
   4. Exposure to UV radiation increases melanocyte.

Question 22

Specialized cells that serve as antigen-presenting cells in the skin.

Answer 22

Langerghans cells

Question 23

What are the three primary layers fo the skin (not the strata)?

Answer 23

1. Hypdermis
2. Dermis
3. Epidermis

Question 24

What are the two layers of the dermis?

Answer 24

1. Papillary
2. Reticular

Question 25

Layer of the dermis which consists of connective tissue.

Answer 25

Papillary (above the reticular layer)

Question 26

Layer of the dermis with blood vessels, sweat glands, and hair follicles.

Answer 26

Reticular Layer (above the papillary)

Question 27

Most sensory receptors are located in the dermis. List the four major sensory receptors in the dermis and what stimulates these receptors.

Answer 27

1. Merkel Cells: Deep Pressure and Texture Sensation
2. Meissner’s Corpuscles: Light Touch
3. Ruffini Ending’s: Stretch
4. Pacinian Corpuscle: Deep Touch and Vibration

Question 28

Layer of connective tissue that connects the skin to the rest of the body. Fibrous and contains fat.

Answer 28

Hypodermis

Question 29

List the thermoregulation mechanisms responsible for cooling the body (skin).

Answer 29

1. Sweat
   
   1. absorbs heat from the body through evaporation of H2O from sweat
   2. Sweat glands are innervated by post-ganglionic cholinergic neurons of sympathetic NS
2. Vasoldiation (also releases heat)

Question 30

List the thermoregulation mechanisms responsible the prevention of heat loss (skin).

Answer 30

1. Piloerection (contracting of arrector pilli muscles)
2. vasoconstriction
3. Shivering
4. Insulation via body fat

(if you don’t understamd how these maintain body temp, google it!)