Unit 8 - Excretory System Flashcards
(119 cards)
1
Q
Define excretion
A
The removal of metabolic wastes, usually nitrogenous, from the body
2
Q
Define defecation
A
The process which rids the body of indigestes, un absorbed food remains, plus bacteria
3
Q
What is excretion of waste products important for?
A
Maintaining homeostasis in the body
4
Q
List the 4 main nitrogenous wastes
A
Ammonia
Urea
Uric acid
Creatine
5
Q
Where is ammonia formed?
A
In liver cells by deamination
6
Q
What are some qualities of ammonia?
A
Ammonia is highly toxic and soluble in water
Some ammonia is also secreted as an ammonium ion (NH4+)
7
Q
What’s the formula for ammonia?
A
NH3
8
Q
Where is urea formed?
A
In the liver by combination of CO2 and 2 ammonia molecules
9
Q
What are some qualities of urea?
A
It’s less toxic
And less soluble in water
10
Q
What are some qualities of urea?
A
It’s less toxic
And less soluble in water
11
Q
How is uric acid formed?
A
When nucleotides are broken down
12
Q
What can uric acid do?
A
Sometimes it can crystallize in joints, causing painful swelling called gout
13
Q
How does creatine form?
A
Forms from break down of creatine phosphate, a high energy phosphate reserve molecule in muscles
14
Q
What does creatine help with?
A
Helps recycling of ADP back to ATP by giving it a phosphate
15
Q
What does creatine help with?
A
Helps recycling of ADP back to ATP by giving it a phosphate
16
Q
How do fish excrete nitrogenous wastes?
A
Fish secrete ammonia directly into the water through their gills
17
Q
How do birds and reptiles excrete nitrogenous wastes?
A
They secrete uric acid when they poop
18
Q
How do humans excrete nitrogenous wastes?
A
Humans and all other mammals produce urea and excrete the waste product through urination
19
Q
What are some other waste products?
A
Water
Salt
CO2
Bile pigments
20
Q
Describe the waste product water
A
End product of metabolism (cellular respiration in the mitochondria)
Plays a major role in blood pressure
21
Q
Describe the waste product salts
A
Excreted maintaining proper concentration in blood ph, osmotic pressure and electrolyte balance
22
Q
Describe the waste product salts
A
Excreted maintaining proper concentration in blood ph, osmotic pressure and electrolyte balance
23
Q
Describe the waste product CO2
A
End product of metabolism (cellular respiration in the mitochondria)
Excreted primarily from lungs
Solvable in blood, combines with H2O to make H2CO3/HCO3-
24
Q
Describe the waste product bile pigments
A
From heme portion of Hb (blood)
Mixed into bile by liver and stored in gall bladder
25
Describe the waste product bile pigments
From heme portion of Hb (blood)
Mixed into bile by liver and stored in gall bladder
26
What organs are s’associât es with the excretion of waste products?
Lungs
Kidneys
Skin
Liver
27
What is urine composed of?
95% water
2% urea
1.63% salt ions
0.1% creatine
0.05% ammonia
0.03% uric acid
28
What are the 4 functions of the urinary system?
Filter blood and remove wastes
Osmoregulation
Maintain blood ph at 7.4
Secretes an enzyme and hormone that regulate water retention
29
Explain osmoregulation
Maintaining blood volume and pressure
The kidney can increase or decrease salt retention in the blood
Kidneys also help maintain blood levels of other ions such as potassium, bicarbonate and calcium in the blood
30
What does it mean if there is more salt in the blood?
There is a greater blood volume and pressure because salt draws water into the blood via osmosis
31
What does it mean if there is less salt in the blood?
Less blood volume and pressure because less salt draws less water into the blood via osmosis
32
What does it mean if there is less salt in the blood?
Less blood volume and pressure because less salt draws less water into the blood via osmosis
33
How is blood ph maintained?
By excreting hydrogen ions and reabsorbing the bicarbonate ions as needed
34
What is the ph of human urine?
6 or lower because food is often acidic
35
What is step one to secretion?
The kidneys release renin, an enzyme that leads to the secretion of the hormone aldosterone from the adrenal cortex, which leads to reabsorption of sodium ions and more water into the blood
36
What is step two to secretion?
The kidneys also release ADH, which causes the kidneys to reabsorb more water into the blood
37
Describe the kidneys
Paired, bean shaped reddish brown organs.
About the size of a fist
Covered by a tough fibrous connective tissue called a renal capsule
38
Where are the kidneys located?
Near the small of the lower back, some protection from rib cage
39
Where are the kidneys located?
Near the small of the lower back, some protection from rib cage
40
Where are the kidneys located?
Near the small of the lower back, some protection from rib cage
41
What does the adrenal gland do?
It sits on top of each kidney and produces hormones
42
What does the renal artery do?
Brings unfiltered blood into the kidney
43
What does the renal vein do?
Takes filtered blood away from the kidney
44
What are ureters?
Muscular tubes about 25 cm long and 5 mm in diameter
45
What do ureters do?
Move urine from kidneys to bladder via peristalsis, about 1-2 squirts per minute
46
How much urine does a human produce per day?
1-2 litres
47
What does the urinary bladder do?
Stores urine until it is expelled from the body
48
What does the bladder wall have?
Stretch receptors which make the walk expandable and notify the brain when it’s full
49
What do the two sphincters in the bladder do?
Control the exit of urine to the urethra because the internal sphincter is composed of skeletal muscle
50
What is the urethra?
A small tube that extends from the bladder to an external opening
In females 4cm long
In males 20 cm long
51
In females how is the reproductive system?
Separate
52
In males the reproductive system is merged, how does it work?
The urine use the urethra during urination and semen uses the urethra during ejacualtion
53
What is step one in the process of urination?
When the bladder fills to about 250ml with urine, stretch receptors send sensory nerve impulses to the spinal cord
54
What is step two in the process of urination?
Motor nerve impulses from the spinal cord cause the urinary bladder to contract and the sphincters to relax
55
What is step three in the urination process?
Urination occurs
56
What is step four of the urination process?
In older children and adults the brain controls this reflex, so urination is delayed until a suitable time
57
What is step four of the urination process?
In older children and adults the brain controls this reflex, so urination is delayed until a suitable time
58
What is the renal cortex?
Outer region of the kidney
Consists of about 1 million filtration units called nephrons as well as blood capillaries
Site of blood filtration
59
What is the renal medulla?
Inner region of the kidney, not including the pelvis
Consists of a few more nephrons, but mostly collecting ducts which make up the renal pyramids
Bring filtered liquid waste to the pelvis (urine)
60
What is the renal pelvis?
Collects urine and sends it down the ureter to the bladder
61
Where can kidney stones be formed?
In the pelvis. There are 4 types and they are all a combo of calcium, phosphate, oxolate, or uric acid
62
What is a nephron?
A filtration unit found in the kidney; urine formation occurs here
63
What does each nephron have?
It’s own blood supply, including 2 capillary regions
64
How much does the nephron process each day?
About 180 L of filtrate but excretes only 1.5 L of urine
65
What are the parts of the nephron?
Bowman’s capsule
Proximal convoluted tubule
Loop of Henle
Distal convoluted tubule
Collecting duct
66
What are the parts of the capillary network?
Afférent arteriole
Glomerulus
Efferent arteriole
Peritubular capillaries
Vasa recta
67
What is the overall pathway of blood in the kidney?
Renal artery, afférent arteriole, glomerulus, efferent arteriole, peritubular capillaries/vasa recta, venule, renal vein
68
What is the process of urine formation?
1. Glomerular filtration
2. Tubular reabsorption
3. Reabsorption of water
4. Tubular secretion
69
Where does urine go once formed in the nephron?
Goes down the collecting duct into the renal pelvis, ready for excretion
70
Where does glomerular filtration occur?
In the bowman’s capsule
71
Describe the bowman’s capsule
Cup like structure that surrounds a mass of blood vessels called the glomerulus
72
Does the afferent arteriole bring blood into or out of the glomerulus?
Into
73
What is the size of the afferent and efferent arterioles?
Afferent is large
Efferent is small
74
What do pores allow for?
Allows easy passage of small molecules from the blood into the bowman’s capsule
75
All small molecules move into the nephron to form what?
The filtrate where movement is passive and non specific
76
What happens to large blood components?
RBCs, WBCs, platelets and proteins do not filter across and remain in the blood
77
What does the smaller diameter of the efferent arteriole help with?
Contributes to the pressure applied at the glomerulus
78
Why is the blood leaving the glomerulus more concentrated?
Most of the water and smaller molecules have been removed
79
What is the pressure of the afferent and efferent arterioles?
Afferent - higher
Efferent - lower
80
What level of urea, glucose, and water is in the afferent and efferent arterioles?
Afferent - high
Efferent - low
81
Where does tubular reabsorption occur?
Primarily in the proximal and distal convoluted tubules
82
What does tubular reabsorption connect and what surrounds it?
It connects the bowman’s capsule to the loop of henle and is surrounded by the peritubular capillary network
83
What do the cells lining some areas of the nephron have and why? (Tubular reabsorption)
Microvilli to increase surface area and reabsorption of desired filtrate components like glucose, aa, and water back into the blood stream
84
How is movement in tubular reabsorption?
Movement is selective and active
Each cell in the pct has many mitochondria for energy for active transport of molecules
85
In tubular reabsorption how much water goes back into the blood and by what?
About 75% moves passively by osmosis
86
In tubular reabsorption are all things reabsorbed into the blood?
No, some water, excess salts, and wastes are not reabsorbed and move onto the loop of henle
87
Where does the reabsorption of water occur mainly?
In the loop of henle and the collecting ducts
88
What does the descending loop of henle allow for?
Allows water to leave the nephron where it is absorbed back into the capillaries
89
What does the ascending loop of henle have and what does it do?
It has an impermeable wall and does not allow water to leave. It transports put salt into the medulla and blood capillaries
90
What direction does blood flow in the vasa recta?
Moves in the opposite direction than the filtrate in the nephron
91
What allows for slate to move into the blood at the ascending loop of henle?
The opposite flow of blood
92
What does salt do in the descending loop of henle?
Sucks the water into the blood by osmosis
93
What happens when the loop of henle descends deep into the medulla of the kidney?
The more concentrated the interstitial fluid surrounding the nephron becomes (hypertonic). This is due to slat and urea being more concentrated in the centre of the kidney and contributes to a greater pull of water out of the nephron
94
What is the wall of the collecting ducts permeable to?
Water and urea
95
As the collecting duct moves down into the concentrated medulla what happens?
The water is sucked out and put back into the blood and medulla via osmosis
96
What happens with the loss of water in the collecting duct?
The urea in the filtrate becomes more concentrated. Because there is so much urea in the collecting duct, some of it diffusés down its concentration gradient and back into the blood and medulla
97
Where does tubular secretion occur?
Mostly in the proximal and distal consulted tubules
98
What enters into one collecting duct?
Several convoluted tubules, they then carry urine to the renal pelvis
99
When the blood is acidic what happens at the duct?
Excess H+ ions are put back into the filtrate, making urine more acidic
100
When the blood is acidic what else does the duct do?
The bicarbonate ions are actively transported back into the blood.
101
What happens to the kidneys if you are dehydrated?
The Kinsey’s can excrete a small, concentrated volume of urine and reabsorb the majority of water from the filtrate.
The urine will be very little and dark yellow
102
What happens to the kidneys if you are dehydrated?
The Kinsey’s can excrete a small, concentrated volume of urine and reabsorb the majority of water from the filtrate
103
If you have an excessive amount of fluid what happens to your kidneys?
They excrete a large, dilute volume of urine, with very little water being reabsorbed from the filtrate
You will have lots of pale urine
104
How do we maintain the proper amount of water in our bodies?
It is controlled homeostatically with two hormones
Antidiuretic hormone (ADH)
Aldosterone
105
What does antidiuretic hormone control?
This hormone controls water reabsorption with a negative feedback cycle
106
What makes ADH and where is it stored?
The hypothalamus makes ADH
It is stored and released from the posterior pituitary gland
107
What happens with ADH when you have low blood volume? (Dehydrated)
The osmoreceptor cells in the hypothalamus triggers the posterior pituitary to release ADH
108
Where does ADH move through and what does it increase?
ADH moves through the blood to the kidneys and increases the permeability of the distal convoluted tubule and collecting ducts to water, causing more water to be reabsorbed into the blood and increases blood volume
109
With ADH when water is being removed from the filtrate what happens?
The concentration of urine increases. Your urine will be less and dark
110
What is ADH mechanism controlled by?
Negative feedback. Once blood volume is back to normal and osmolarity is lower, the posterior pituitary gland stops releasing ADH
111
What does alcohol do with ADH?
It inhibits the release of ADH, causing excessive loss of water in the urine and dehydrating the body. Leads to a hangover
112
What is the juxtaglomerular apparatus?
A specialized tissue that surrounds the afférent arteriole of the kidney. It measures blood pressure
113
What happens with JGA when BP drops?
The JGA releases an enzyme celles renin, which activates angiotensin
114
What is angiotensin?
A protein made by the liver which is always circulating around the blood
115
What does angiotensin do?
Stimulates the adrenal gland on the kidneys to release the hormone aldosterone
116
What does aldosterone do?
Tells the distal convoluted tubules of the nephrons to reabsorb lots of salt back into the blood. Water then goes into the blood through osmosis which increase BP
117
What else does angiotensin do?
Causes vasoconstriction of the arterioles. BP rises
118
What happens if BP is too low?
There is not enough pressure to filter the blood properly
Kidneys can not rid the body of drugs and toxins
Not enough blood reaches the brain so you may faint
119
What happens if BP is too high?
The glomerulus may be damaged or burst
Blood cells and proteins will then pass through the nephron and into the urine
