Homeostasis

Question 1

What is homeostasis?

Answer 1

The steady-state balance in the internal environment of an animal’s body that are regulated by a variety of control systems

Question 2

What are the components of control systems?

Answer 2

1. Monitor (sensors in the body detect when an organ is out of balance)
2. Coordinating System (received information from monitor and initials signal to regulator)
3. Regulator (affect the change)

Question 3

What is negative and positive feedback?

Answer 3

Negative: when monitor detects change in variable, signal is sent to coordinating system causing regulator to counter the change

Positive: system reinforces the change, less common

Question 4

What are the 3 types of regulation in the human body?

Answer 4

Thermoregulation
Osmoregulation
pH

Question 5

What is thermoregulation? Why is it important?

Answer 5

Maintenance of body temperature within a range that allows them to function efficiently

Importance because proteins change their conformation with temperature

Question 6

What is the monitor for thermoregulation?

Answer 6

• Sensors in brain detect rise in body temperature

- Thermoreceptors in skin detect drop in external temperature

Question 7

What is the coordinating system for thermoregulation?

Answer 7

Primative brain/brain stem: the hypothalamas

Question 8

What are the regulators for thermoregulation? What do they do?

Answer 8

TOO HOT: dissipate heat
Sweat glands: evaporation cools skin
Vasodilation: increase heat loss by radiation (blood vessels)

TOO COLD: reduce heat loss/make heat
Vasoconstriction: conserve heat (blood vessels)
Piloerector muscles: causes hair to stand up to trap warm air
Brown fat: make heat by cellular respiration
Muscles: cause shivering, producing heat

Question 9

What is the role of the kidney in homeostasis?

Answer 9

• Water balance
• Maintains solute concentrations
• Eliminates N wastes (toxic by products)
• Regulates pH ([H+])

Question 10

What is the function of the kidney (how does it carry out its role)?

Answer 10

• Filter blood: movement of fluids from blood into nephron
• Reabsorb valuable solutes: active and passive transport return substances to blood
• Secrete solutes: everything left over is excreted

Question 11

Answer for the glomerulus and Bowman’s capsule:

• Substance transported?
• Method of transport?

Answer 11

Plasma minus proteins

Bulk flow

Question 12

Answer for proximal tubule:

• Substance transported?
• Method of transport?

Answer 12

Ions, water, glucose, amino acids (100% retrieved)

Active + passive transport

Question 13

Answer for descending/ascending loop of Henle:

• Substance transported?
• Method of transport?

Answer 13

H2O/NaCl

Passive transport/Passive + active transport

Question 14

Answer for the distal tubule:

• Substance transported?
• Method of transport?

Answer 14

Ions

Active + passive transport

Question 15

Answer for the collecting duct:

• Substance transported?
• Method of transport?

Answer 15

Wastes

None

Question 16

How is urine formed?

Answer 16

• Selectively permeable glomerulus and pressure forces small ions with fluid into Bowman’s capsule
• This fluid enters proximal tubule using the active and passive transport of ions to bring in the fluid, substances are reabsorbed to capillaries
• Fluid enters loop of Henle which is permeable to water on descending side and salt to the ascending
• Water diffuses in, then salt is actively transported out
• Distal tubule fine tunes concentration and in the presence of ADH (increases permeability of H2O), more water is absorbed
• Collecting tubule actively reabsorbs NaCl and alters concentration of water

Question 17

Where is urine formed? What is the components of this system and their function?

Answer 17

Nephron (functional unit of kidney)

• Cortex: outer layer of kidney (protects)
• Medulla: inner layer of kidney (has concentration gradient)
• Renal Pelvis: hollow cavity (connects kidney to ureter)
• Ureter: tube (sends urine to bladder)
• Urethra: tube exits bladder (urination)
• Afferent Arteriole: incoming (supply blood to glomerulus)
• Efferent Arteriole: outgoing arterial (supply blood to peritubular capilaries)
• Pertitubular Capillaries: capillary network (collects reabsorbed material)
• Glomerulus: leaky capillaries (filters blood)
• Bowman’s Capsule: folded structure (collects filtrate or filtered left over)
• Proximal Tubule: folded tube (reabsorb 85% of filtrate)
• Loop of Henle: U shaped tube (reabsorb H2O and NaCl)
• Distal Tubule: folded tube (reabsorb or secrete based of hormonal regulation)
• Collecting Duct: branched tube (collect urine, sent to pelvis, fine tune urine concentration)