Renal system Flashcards
1
Q
Position of kidney
A
Posterior abdnomial wall
Between T12 and L3
2
Q
Functions of kidney
A
- Maintenance of homeostasis
- Formation of urine
- Excretion of waste products and toxins
- Regulation of electrolyte balance
- Regulation of fluid balance
- Regulation of acid: base balance
- Produce renin – control blood pressure
- Produce erythropoietin
- Metabolism of vitamin D (convert inactive to active)
3
Q
Whats a nephron?
A
- Functional unit of kidney (approx. 1 million)
4
Q
What are components of nephron?
A
- Glomerulus
- Bowmans capsule
- Proximal convoluted tubule
- Nephron loop/ loop of Henle (ascending and descending)
- Distal convoluted tubule
- Collecting duct
5
Q
Whats pathway of blood through nephron?
A
- Glomerulus
- Bowmans capsule
- Proximal convoluted tubule
- Nephron loop/ loop of Henle (ascending and descending)
- Distal convoluted tubule
- Collecting duct
6
Q
HWat three processes in the formation of urine?
A
- Glomerular – filtration
- Tubular – reabsorption
- Tubular – secretion
7
Q
Whats the afferent arteriole?
A
Plasma in to glomerulus starting filtration
- Grancular cells on afferent arteiole release renin
8
Q
Whats the efferebt arteriole?
A
Plasma leaves the glomerulus
9
Q
Whats the juxta-glomerular apparatus?
A
In charge of production and release of renin
- Macular denser cells in ascending limp of loop of Henle monitor sodium concentration in filtrate
- Granular cells on afferent arteriole release renin
10
Q
Whats renin?
A
Controlling blood pressure by amount of water we reabsorb and eliminate through aldosterone release
11
Q
What are the stages of the filtration membrane in the kidney?
A
-selection process – in glomerulus
- three stages in filtration
1. fenestrations endothelial cells (pores)
2. filtration membrane
3. podocytes
12
Q
What are Fenestrations endothelial cells?
A
- First stage of filtration
- Retaining large molecules and allowing smaller to proceed eg. proteins
- Pores.
13
Q
Whats the filtration membrane?
A
- 2nd stage of filtration
- Second filter
- Two characteritsics – stopping big molecules (if slip through fenestration pores) and negativily charged so reject negatively charged moelcules eg. Ions
- Allow positively charged small molecules
14
Q
What are podocytes?
A
- 3rd stage of filtration
- Filter and retain large (smaller than fenestration) molecules eg. Blood cells, proteins.
- Produces the filtrate
- After goes on to proximal convalunted tubulae
15
Q
What is filtration?
A
- Movement of water and solutes from blood into filtrate under pressure
- Rate at which kidney/nephron filters the blood is known as glomerular filtration rate
- Filtrate passes into proximal convolted tubule containing everything in the blood except red and white blod cells, platelets and large proteins like albumin
- Filtrate contains – glucose, amino acids, vitamins, electrolyes, nutrients, water
16
Q
What does filtrate contain?
A
glucose, amino acids, vitamins, electrolyes, nutrients, water
no proteins - harmful
17
Q
What is the glomerular filtration rate?
A
- Rate at which kidney/nephron filters the blood
- GFR = approx 125m/minute (180 literes of filtrate per day)
- Blood pressure and hydro-static pressure mainstains GFR as well as auto-regulation
- Reabsolption – means most of filtrate is being reabsobed
18
Q
What actions promote filtration?
A
- Arterial blood pressure
- Net filtration pressure
19
Q
What is net filtration pressure?
A
- Sum of forces
Out: - Hydro-static pressure (glomerular) in glomerular capillaries
- Efferent arteriole narrower than afferent
In: - Pressure in capsular space
- Colloid osmotic pressure in capillaries
Net outward force of 10mmHg
Outward pressure – inwards pressure
Hydro-static pressure – pressure in capulsue space – capillary pressure.
20
Q
Diameter differences in arterioles?
A
- Efferent (out) narrower than afferent (in)
21
Q
What is auto-regulation?
A
- Pressure is high – afferent arteriole constricts reducing pressure entering glomerulus
- Pressure is low – efferent artertiole constricts to increase pressure in glomerulus
- Low pressure in afferent arteriole also stimulates releasing renin (luxta glomerular apparatus)
22
Q
What are Different mechanisms involved in auto-regulation - When low blood pressure in kidney?
A
- **Myogenic mechanism of autoreulgation **-
- Tubulaglomerular mechanism of autoregulation -
- ** Hormonal (renin-anglotensin-andosterone) mechanism **
- **Neural controls **
23
Q
How is the Hormonal (renin-anglotensin-andosterone) mechanism involved in autoregulation?
A
– juxtaglomerular **release renin **
- catalysing cascade forms angiotensin
- **vasoconstricts systemic artioles **
- **increasing peripheral resistance **
- secretes aldosterone bu adrenal cortex so increased sodium absoption and water so increaisng blood volume increaisng systemic blood pressure
24
Q
How is the myogenic mechanism involved in autoregulation?
A
Afferent arterioles vasodilate (smooth muscle in walls)
25
How is the tubulagomerular mechanism involved in autoregulation?
- Reduced glomerulus filtration rate in ascending loop acts on **macula densa cells **of juxtraglomerulae complex of kidney **releasing vasoactive chemicals** causing **vasodilation** of **afferent** arterioles
26
How is the neural control involved in autoregulation?
- **inhibits barorecpetors **in blood vessels activating **sympathetic** nervous system which starts **hormonal response** and causes **vasoconstriction** of arterioles
27
What is tubular reabsoption?
- Return of useful substances and water from filtrate to blood
- Selective process starting in PCT
- Sodium actively reabsorbed from filtrate into blood
- Loop concentrated the filtrate then dilutes it
- Descending limb is permeable to water not salts – so water lost and gradient formed so high osmolality ending ascending
- Ascending limp imperable to water pumps out salt
- Water, some ions and nutrietns follor passively by osmosis, diffusion and facilitated diffusion
- Until transport maximum is reached
- Happens in PCT – effected by active, passive and hormonal processes (ADH and aldostrone)
28
What is transport maximum?
- Max amount of substance that can be reabsobed
- If glucose exceeds this it is lost in the urine – glycosuria
29
What is glycosuria?
- Level of glucose exceeds the transport maxiumum its lost in the urine
30
What hormones effect reabsorption in kidneys?
- Aldostrone – influence reabsorption in DCT
- ADH – affects permeability of collecting duct to water
- Parathyroid hromone regulating calcium absorbed
31
What is tubular secretion?
- Active removal of unwanted substances/wastes from the blood into the filtrate
- Occurs along tubule – potassium maining in PCT also sodium in DCT
- Hydrogen ions, potassium, ammonium, creatinine, drugs
- Therefroe improtant to regulate potassium and pH levels
32
WHat is urine chemical composition?
- 95% water
- Urea – frim normal breakdown of amino acids
- Sodium, potassium, phosphate, sulphate
- Creatinine – from metabolism in muscle tissue
- Uric acid – from metabolism of nucleic acids
33
How are medications effected by urine?
- They are excreted by kident so doses may be altered in renal dysfunction§
34
What is osmolaity?
- Number of solute particles in 1 kg of water
35
What is vasa recta?
- Curve/bottle point of limb of henle
- Highly permeable to water and solutes so preseved the gradient
36
Why is anti-diuretic hormones effect kidneys?
- - influenes the permeability of collecting duct and latter part of distal tubule
- The aquoporin channels allow wtaer movement
- Plasma osmolarity is detected by osmo-recetopes in hypothalamus
- ADK secretion from posterior pituitary increases or decreases response to osmolaity
- Increased ADH = greated reabsorption and less urine
- Decreased ADH = less reabsortion = more urine
37
What are renon-angiotensin-adosterone mechanisms?
- Sodium and water movement controls blood pressure
- Renin released in repsonse to low pressure
- Converts angiotensinogen (inactive proetin) into angiostein 1 (active) - converted to 2 by angiotensin converting enzyme from lungs
- Causes vasoconstriction of systemic blood vessels
- Releases aldosterone hormone from adrenal cortex causieng reabsorption of sodium and water in renal tubules
- Influences ADH release
38
What does angiotensin 2 cause?
- Causes vasoconstriction of systemic blood vessels
- Releases aldosterone hormone from adrenal cortex causieng reabsorption of sodium and water in renal tubules
- Influences ADH release
39
What does aldosterone do?
- Targets kidney tubles
- Increasing sodium reabsoption
- Increaisng potassium secretion
- Restores homeostatic plasma levels of sodium and potasssium
40
Whats the regulation of acid base balance?
- Hydrogen ions produced in metabolism need to be eliminated as more in blood means lover pH and or OH- in blood means higher pH of blood
41
What are Mechanisms to maintain acid base balance?
- **Buffers eg. Bicarbonate, proteins and phosphate –** acting as sponse to soak up excess H and OH
- Respiratory centre detects highened so inreases breathing rate to breath it out as carbon disoxdie
- If falls then secreted in the kidneys into the urine as hydrogen combines with buffer and is excreted
42
How is erythropoietin produced?
- Produced by kidneys
- Stimulates bone marrow to produce red blood cells – erythropoiesis
- Stimulated by hypoxaemia
43
How is calcium and phosphate regulated in vitamin D metabolism?
- Main hormonal control of calcium homeostasis is released by parathyroid hormone
- In kidkensy calsium is resbsobed and the metabolism of vitamin d into an active form (absorbed by skin from sunlight from modified cholesterol)
- Calcium can also be reabsobed as phosphate and excreted
44
What does vitamin D do in kidneys?
- Active vitamin D
- Stimulates absoption of calcium from the GIT
- Minatains normal blood calcium levels
45
What is calcium needed for in kidneys?
- Strong bones and teeth
- Normal transmission of the nerve impulse
- Normal muscle contraction
- Blood clotting
46
What is calcium regulation?
- Hypocalcemia – low blood calcium levels
- Increase parathroid hormone
- Increased osteoclast activity in blood so calcium and PO4 3- is released into blood
- Increased calcium reabsorption in kidney tubule
- Increased activation of vitamin D by kidney which increased calcium absoprtion from food in the small intestines
