Topic 9.9 Flashcards
The autonomic nervous system is split into parasympathetic and sympathetic
SNI
PAS
Use noradrenaline as its neurotransmitter and incr heart rate
Parasympathetic uses acetylcholine as its neurotransmitter and decre heart rate
Baroreceptors
Chemo receptors
Baroreceptors – Detect changes in pressure, found in walls of heart and major blood vessels
Chemo receptors – Detect changes in carbon dioxide concentration
The rate at which the
sympathetic and
parasympathetic neurones
send electrical impulses to
the heart is controlled by
The medulla
If blood pressure rises
If blood pressure lowers
Baroreceptors signal to medulla , parasympathetic branch releases acetylcholine, slows SAN , decreases heart rate
Baroreceptors signal to medulla , sympathetic branch releases, noradrenaline, speeds SAN , heart rate increases
Low Co2 / high pH
Chemoreceptors signal medulla , parasympathetic branch releases acetylcholine, slows san
Low pH
low pH in the
blood, is detected by chemoreceptors in the carotid artery, effects medulla oblong, sympathetic nerve stimulated , noradrenaline at san, more impulses increase heart rate
What’s ultrafiltration
Ultrafiltration occurs in the kidneys within the glomerulus of the nephron. It is the process by which small molecules are filtered from the blood into the Bowman’s capsule under high pressure.
What are the steps of ultrafiltration
the glomerulus blood pressure is high, it forces small molecules eg amino acids into the bowmans capsule
how is the high pressure in the glomerulus generated?
bc blood is under high pressure in the glomerulus as the afferent arteriole is wider than the efferent arteriole .
during ultrafiltration molecules are forced out the glomerelus and into the bowmans capsule but to make sure not every molecule is pushed out there are filters in place:
- fenestrated endothelium - tiny gaps in the glomerular wall prevent blood cells leaking out
- the basement membrane , prevents large proteins leaking out the glomerelus eg plasma proteins
- podocytes - inner wall of bowman’s capsule , contains gaps to allow glomerular filtrate to leak thru, limits amount of filtrate that passes thru and enter lumen
whats selective reabsorption
the reabsorption of some molecules from the glomerular filtrate back into the blood, this is done by the proximal convulted tubule
this is bc we dont wanna wee everything from the glomerular filtrate out, as this wont be good for us bc of how much substances our body will then loose, so instead its reabsorbed
how does reabsorption of sodium take place?
-sodium is actively transported out the cell by the Na/k pump, carried away by blood, this lowers the conc of Na ions in the cell
-OCCURS IN PROXIMAL TUBULE
how does reabsorption of glucose take place?
glucose and aa are actively transported by cotransporter proteins along w sodium into the epithilial cells, lowering the water poten, water moves in my osmosis
-OCCURS IN PROXIMAL TUBULE
-glucose and aa diffuse down conc gradient into blood
5.) Water moves down
water potential gradient
into blood by osmosis.
4.) Glucose and amino
acids diffuse down
concentration gradients
into blood (facilitated
diffusion out of cells into
intracellular spaces, then
passive diffusion into
blood)
3
1
Reabsorption
2
4
5
6.) Other mineral ions (K+
, Cl- etc)
travel through the epithelial cell and
into the blood by facilitated diffusion
Explain how the loop of Henlé is involved in the production of
concentrated urine
Filtrate moves into pct
Moves down descending limb , water moves out by osmosis into tissue fluid and into blood
Descending limb is impermeable to Na+/Cl- ions
At the medulla there’ll thus be a lower water potential
The ascending limb is impermeable to water Na + and cl- move out by active transport
Loop of henle act as counter current multiplier
Collecting ducts permeable to water,, water moves out by osmosis
What happens to the filtrate after moving thru the loop of henle
moves into Distal Convoluted Tubule (DCT)
• Further reabsorption of sodium ions (Na⁺) occurs, regulated by aldosterone.
• Water reabsorption also happens, controlled by antidiuretic hormone (ADH).
When the pituitary gland detects there’s too little water in the blood what happnes
It releases more of the hormone ADH which increases the permeability of the collecting duct to water, increased water absorption into vasa recta , increasing urine conc
If the collecting duct is permeable
Water is absorbed by osmosis from the CL back into the blood
What if there’s too much water in the blood
Receptors in hypothalamus detect this , pituitary gland releases less ADH , decreasing permeability of collecting duct to water, decreased water reabsorption into vasa recta diluted urin
ADH positive feedback
ADH binds to specific receptors on the surface of distil tubule cells
This triggers a series of reactions that result in the production of cAMP that
acts as a second messenger
cAMP causes vesicles containing water channels to fuse with the cell
membrane
These water channels are inserted into the cell membrane which t
becomes more permeable to water, More water moves through the tubule cells by osmosis and into the
surrounding blood
Less water is lost in urine
ADH negative feedback
Less ADH binds to specific receptors on the surface of DCT
and collecting duct cells
Less cAMP produced
Water channels are withdrawn from cell membranes
The membranes become less permeable to water, Less water is reabsorbed into blood by osmosis
More water is lost in urine (large volume of dilute urine
produced)
Kangaroo rats live in very dry environments but still need to produce urin to get rid of toxic waste eg urea , how are they adapted
Their kidneys are adapted to produce a tiny amount of conc urine
-beh : live in burrows with a lower and stable temp
-many juxtamedullary nephrons, long loops of henle with long descending limbs , many mitochondria for efficient respiration
What’s an ectotherm
An organisms that regulates its body temperature with the help of external sources, unable to increase their respiration rate to incr the internal, production of heat , can’t rely ion internal energy sources
Disadv- very vulnerable to predators in cold temps
Endotherms
Able to maintain a constant body temp, independent of the external temp
They have thermoreceptors to monitor core body temp, communicate w hypothalamus
When the hypothalamus detects an increase in body temp
Sweating takes place , sweat production decreases body temp thru evaporation from skins surf
Vasodilation- widening of blood vessels , increasing blood to skins surface , allowing heat loss to surroundings , by radiation
• Erector pili muscles
contract, pulling hairs
upright – this traps an
insulating layer of air and
reduces heat loss from
the skin.
When the hypothalamus detects the body becoming cold
Vasoconstriction- blood vessels reduce blood flow to the surface of the skin to reduce heat loss to surroundings
Shivering - muscle contraction leads incr in temp as heat’s released
Hairs stands to provide insulation and reduce heat loss
Reduced sweating to preserve heat loss
How is urea produced in mammals
The removal of an amino group from an amino acid
Ammonia combines with co2
How’s a proximal convoluted tubule specialised
Many mitochondria, atp active uptake of glucose
Microvili large surface area
For many carrier proteins for glucose
If wood mice are trapped why can’t they maintain they’re own body temp
Large sa:v , so loose heat quickly ,
Heat is generated by respiration
Insufficient food to release enough energy
Furosemides are drugs that are used to reduce oedema. They are diuretics that
increase urine production.
Furosemides reduce the active transport of sodium ions by the loop of Henle.
Explain how furosemides cause an increase in urine production.
• sodium ions are not removed from the ascending limb
• so the water potential of medullary fluid is higher
• less water is removed from the descending limb
• dilute concentrationurine is produced
How do endotherms survive cold environment
They are larger so they have a smaller sa:v
They develop thick layers of fat as insulation , reducing heat loss
Hibernation , slows metabolic rate , allows energy to be conserved
