Excretory system & Homeostasis Flashcards
What are the labels of the excretory system
Renal artery Renal vein Kidney Ureter Bladder Urethra
What is the function of the Bladder
Stores urine
What is the function of the Ureter
Caries urine from the kidney to the bladder
What is the function of the Urethra
Connects bladder to the outside
Define metabolism
The sum of chemical reactions in the body
Define homeostasis
keeping the conditions within the body constant
Why is homeostasis necessary
- To allow metabolic reactions to take place at a suitable rate.
- To provide a suitable temp for enzymes to work properly
Define osmoregulation
maintaining water and salt balance in the body
Define excretion
the removal of the waste products of metabolism from the body
Define egestion
the removal of the undigested materials from the body
What controls temp in the body
- metabolism (produces heat)
2. sweating (cools the body)
What is hypothermia
When your core body temp drops
What organs are involved in excretion
- Kidneys: Urea, excess salts and water in urine
- Lungs: Carbon dioxide and water in breath
- Skin: water and salt through sweat
What is the function of the renal artery
Brings impure blood from heart
What is the function of the renal vein
Brings purified blood to vena cava
What is the nephron
The Nephron is the Functional Unit of Kidney
In terms of urine formation, what is filtration?
It occurs in the cortex.
- Blood in the arteriole is under pressure due to narrowing of blood vessels - Plasma and small molecules forced from glomerulus into Bowman’s capsule - Large molecules and blood cells cannot pass into Bowman’s capsule as they are too big
In terms of urine formation, what is reabsorption?
- Proximal Tubule: substances needed by the body such as glucose, vitamins, amino acids, some salts
and water pass from glomerular filtrate back into the blood by diffusion, active transport and osmosis - Loop of Henle and the distal convoluted tubule: more water is reabsorbed.and salt is balanced
- Collecting Duct: final water reabsorption under the influence of ADH (anti-diuretic hormone)
What is diffusion
The movement of substances from high concentration to low concentration. It does not require energy
What is active transport
The movement of substances from low concentration to high concentration. Energy is needed
what is osmosis
Osmosis is diffusion of water across a semi-permeable membrane
What happens when there is Low water concentration in blood
- if not enough water in blood due to sweating or salty food, more ADH (vasopressin) released
- Which allows more water to be reabsorbed into blood by the
collecting duct - Resulting in small amounts of strong urine
This process is monitored by medulla
What happens when there is high water concentration in blood
- If too much water in blood due to drinking excess water,Less ADH (vasopressin) released
- Which allows less water to be reabsorbed into blood by the collecting duct
- Resulting in large amounts of watery urine called diuresis.
What are endotherms
animals whose body temperature is constant Eg: mammals
What are ectotherms
animals whose body temperature varies with environmental temperature
e.g. fish, reptiles
What happens when the body is too cold
a) Hair stands erect to trap layer of insulating air
b) Arterioles leading to capillaries in the skin narrow to keep
blood flow away from skin. (vasoconstriction)
c) This reduces heat loss
d) Lack of blood near the surface makes the skin pale
e) Shiver to produce heat by muscle movement
f) There is also a layer of fat to insulate body against
heat loss
What happens when the body is too hot
a) Hair lies flat, so no insulating air trapped
b) Sweat produced. Water evaporates which cools the skin
g) Arterioles leading to capillaries in the skin relax to allow blood to flow nearer the surface (vasodilatio)
c) This allows heat to escape more easily
d) Large amounts of blood near the surface makes the skin red
Carbon dioxide levels in the blood
- monitored by the brain
Used to control breathing rate
As CO2
levels rise the blood becomes more acidic
This results in an increase in breathing rate and depth
CO2 levels in plants
- low levels of CO2 in the air spaces in the leaf stimulate the opening of the stomata
- High levels of CO2 in the air spaces in the leaf stimulate the closing of the stomata
What is the location of the kidney
The rear abdominal cavity
The nephron’s diagram labels
- Afferent arteriole: blood under pressure because of narrowing of blood vessel
- Glomerulus: ultrafiltration under pressure removes soluble impurities
- Bowmans capsule: collects filtrate
- Proximal convoluted tubule: useful substances reabsorbed into capillaries
- Efferent arteroile: blood with little plasma
- Distal tubule: salt and water balance.
- Collecting ducts: final salt water balance, water reabsorbed under influence of ADH
- Capillary network: reabsorbs materials from filtrate into plasma
- Loop of henle: salt balance happens here
The kidneys diagram labels
- Cortex: (outside) contains bowmans capsules
- Medulla: (middle) contains PCT, Loop of Henle, DCT and collecting ducts here
- Pelvis: (inside) Collects urine from collecting ducts
