2.1.3 Hormonal Homeostasis/1.2.3 Exchange of Nutrients and Wastes Flashcards
Hormones travel in the ____/____ system and will initiate _______
- blood
- lymph
- signal transduction
Recall the Kidney Process in Osmoregulation
- Blood enters the nephron through the afferent arteriole into the glomerulus
- the afferent arteriole is wide and the blood is under high pressure - The blood enters the glomerulus. This is a knot of capillaries held within a Bowman’s capsule.
- This is where high pressure filtration (ultrafiltration) occurs - The blood is under high pressure
- small molecules such as water, salts, urea, glucose, amino acids, vitamins and used hormones are filtered out of the blood.
- blood cells and proteins remain in the blood - the newly filtered blood leaves the glomerulus through the efferent arteriole
- this has a narrower diameter than the afferent arteriole, causing the blood to be under high pressure in the glomerulus (leading to high pressure filtration). - The filtrate (waste) is now in the proximal convoluted tubule
- all the useful parts of the filtrate are reabsorbed back into the blood through selective reabsorption
- this is all the glucose, some vitamins, some salts and some water - The filtrate now enters the Loop of Henle
- This regulates the amount of water and salt in the body
- First part of the loop is the descending limb
- second part is the ascending limb
- If your blood is watery, then less water is reabsorbed, and a lot of dilute urine is produced
- If your blood is not very watery, more water is reabsorbed and you produce a small volume of concentrated urine. - the regulated filtrate now enters the distal convoluted tubule, before being passed to the collecting duct.
- at this stage, it is urine
- the collecting duct leads to the bladder
Where does ultrafiltration and selective reabsorption occur in the nephron?
Ultrafiltration: glomerulus
Selective reabsorption: proximal convoluted tubule
What is the difference in the blood entering the afferent arteriole vs the blood leaving the efferent arteriole?
afferent: contains waste i.e. dirty blood
efferent: does not contain waste as has been filtered i.e. clean blood
what are the causes of ADH?
- Dehydration
- Less water in blood
- Osmoreceptors cells in hypothalamus lose water (so shrink)
- Stimulates nerve cells in the hypothalamus
- Increased ADH (antidiuretic hormone) production by pituitary gland
- ADH carried in the blood
- ADH arrives at the collecting duct
what is the function of ADH?
makes the walls of the collecting duct permeable so water is reabsorbed
what is the impact of ADH?
- if blood is watery, less ADH is released so you produce more urine
- if blood is not very watery, then more ADH is released, meaning less water is lost in urine
What is a Hydrophytes and what are its characteristics?
Description:
- aquatic plants: floating or living in water
Characteristics:
- have little or no cuticle on stems and leaves
- Stomata found on the upper surface of the leaves
What are Xerophytes and what are their characteristics?
Description:
- dry conditions
Characteristics:
- thick waxy cuticle, hair covering leaves
What are halophytes and what are their characteristics?
Description:
- salt tolerant
Characteristics:
- Many are succulents
- control salt levels in shoots
What are Mesophytes and what are their characteristics?
Description:
- moist conditions
Characteristics:
- perennials - survive underground as bulbs, tubers
- survive with dormant seeds
Define transpiration
The loss of water from a plant by evaporation
What factors affect transpiration?
- temperature: increased kinetic energy of water molecules –> they diffuse faster
- humidity: decreases the concentration of water molecules outside the leaf –> steeper concentration gradient for diffusion
- wind speed: removes water molecules as they pass out of the leaf –> maintaining a steep concentration gradient for diffusion
- light intensity: increased light intensity causes the stomata to open to allow for gas exchange for photosynthesis –> water vapor can diffuse out of the leaf.
What is the function of different parts of the leaf?
Epidermis:
- the outermost layer and secretes a waxy substance called the cuticle.
- The cuticle helps retain water inside the leaf
- the epidermis houses the guard cells which regulate the movement of water into and outside the cell, through opening and closing the stomata.
Mesophyll:
- This forms the middle layer of the leaf.
- It is differentiated into two layers depending on the type of cells found: palisade and spongy mesophyll layers
- Chloroplasts are found here
Vascular Tissue:
- The vascular tissue is found in the veins of the leaf.
- The vascular tissue are composed of xylem and phloem which are responsible for the transport of food and water.
function of the xylem
transports water and dissolved minerals from the roots up to the shoots and leaves
