homeostasis and excretion(kidney)

Question 1

what is homeostasis

Answer 1

homeostasis is the state of steady internal physical and chemical conditions maintained by living systems.
maintaining a certain body temp.

Question 2

what is thermoregulation

Answer 2

maintaining a constant body temperature so that is evening out heat losses and heat gains

Question 3

what is the hypothalamus

Answer 3

an important regulatory centre in the brain which links the nervous system to the endocrine system

Question 4

what is vasoconstriction

Answer 4

a small muscle in an arteriole contracts so the blood flows further from the surface of the skin and this causes less heat loss

Question 5

what is vasodilation

Answer 5

a small muscle in an arteriole relaxes causing the blood to flow closer to the surface of the skin resulting in greater heat loss

Question 6

what is pili erection

Answer 6

as external temperature decreases it causes the pili erector muscle to contract causing hairs to stand up on edge which traps a layer of air between your skin so therefore it reduces heat loss

Question 7

what is sweating

Answer 7

sweat glands release water onto the surface of the skin increasing the rate of heat loss

Question 8

what is shivering

Answer 8

when we shiver our muscles contract rapidly meaning respiration is necessary to supply energy in order to shiver which in turn generates heat

Question 9

what is the function of the hypothalamus in homeostasis

Answer 9

triggers these responses

Question 10

what responses cause heat loss

Answer 10

vasodilation and sweating

Question 11

what responses causes heat gain/prevents heat loss

Answer 11

vasoconstriction, pilli-erection, goosebumps and shivering

Question 12

describe the looping cycle that regulates the glucose levels after digestion

Answer 12

1. meal eaten
2. glucose levels rise
3. insulin is secreted to create glycogen
4. glucose levels fall
5. glucagon is secreted to form glucose
6. glucose levels rise

Question 13

what is excretion

Answer 13

the removal of waste products from metabolic reactions of the body

Question 14

what are examples of excretion

Answer 14

CO2, urea, waste hormones, bile pigments and excess medical drugs

Question 15

what substance is formed from respiration taking place in all living cells, and excreted through lungs as air

Answer 15

carbon dioxide

Question 16

what is produced during respiration excess from food and drink, excreted through the skin, kidneys and lungs, and excreted as sweat, urine or expired air

Answer 16

water H2O

Question 17

what is produced in the liver from the breakdown of surplus proteins, excreted through the kidneys and skin, and excreted as urine or sweat

Answer 17

urea

Question 18

what is formed in the liver cells, excreted through the kidneys, and excreted as urine

Answer 18

waste hormones and toxins

Question 19

what is formed from the surplus of food and cells, excreted through kidney and skin, and excreted as urine or sweat

Answer 19

mineral salts

Question 20

what does the liver and spleen from breakdown of red blood cells, excreted through bile duct into small intestine then gets excreted in the faeces

Answer 20

bile pigments

Question 21

what are the sphincter muscles

Answer 21

hold urine in the bladder for several hours, but when they relax, urine is forced down the urethra and out of the body

Question 22

where are the sphincter muscles based

Answer 22

at the base of the bladder

Question 23

why is homeostasis necessary

Answer 23

The internal environment must be kept within certain narrow limits if an organism is to survive ,however, the external environments are constantly changing so the body needs a way of combatting that

Question 24

what is the first stage of ultrafiltration in the kidneys

Answer 24

Blood is filtered under high pressure through narrow tubes – urea, glucose, water, everything except blood cells and larger molecules is forced out of the “blood”

Question 25

what is the second stage of ultrafiltration in the kidneys

Answer 25

At the proximal convoluted tubule, useful molecules (glucose, minerals, amino acids) plus most of the water are selectively reabsorbed

Question 26

what is the third stage of ultrafiltration in the kidneys

Answer 26

The Loop of Henle alters the salt concentrations in the medulla to aid the reabsorption of water from collecting ducts

Question 27

what is the fourth and final stage of ultrafiltration in the kidneys

Answer 27

In the distal convoluted tubule, more water and some mineral ions are reabsorbed into the blood
The collecting duct’s permeability to water is based on the anti-diuretic hormone (ADH) the more ADH, the more water reabsorbed here, and so less urine produced. In this way the body can fine tune its water level.