Biology LC - Excretion & Homeostasis

Excretion

the removal of metabolice waste from the body

Metabolism

The sum of all chemical reactions that occur in the body

Give one way in which the composition of blood is different from the composition of a glomerular filtrate

• has more water

• conatains glucose, amino acids

Name any two parts of the nephron that reabsorb water

Cortex and medulla

Name any two substances other than water that are reabsorbed during urine formation

glucose and amino acids

What’s meant by filtration?

process where waste is removed from the blood

which part of the nephron is involved in filtration?

Cortex

What is the name of the hormone that effects the reabsorption of water from the nephron? Under what conditions is it secreted?

ADH. It is secreted when there is lower water content in the blood

Explain why urine volume will be low if a person does not regularly drink fluids?

ADH increases permeability of collecting duct

Where in the nephron does ADH act?

Collecting duct

What is the function of the layer of fat which surrounds the kidneys?

Protection

Name a structure which urine travels to the bladder

Ureter

In which part of the kidney is the bowman’s capsule located?

Cortex

in which part of the kidney is the Loop of Henle located?

Medulla

State two features that show how the glomerulus is adapted for filtering blood

• large surface area

• High blood pressure

• Consists of capillaries

• wall is one cell thick

Distinguish between excretion and egestion

Excretion: the removal of metabolic waste from the body

Egestion: The removal of undigested waste from the body

Two excretory products of mammals apart from water

urea, salt, carbon dioxide

Two structures in flowering plants which play a role in excretion

Stomata and lenticels

Homeostasis

The maintenance of a constant internal environment

Why is homeostasis important for the body?

It allows the body to regulate its temperature, allowing the cells to work at their best

Name the parts of the skin involved in Homeostasis and give their function

Sweat Gland: secrete water onto the skin surface

Arterioles: increase blood flow in the skin

Hair: lies flat so there is no layer of air trapped close to the skin to act as insulation

Function of sebaceous gland

produce and release sebum onto the surface of the skin

Distinguish between an ectotherm and an endotherm

Ectotherm: Animal that cannot maintain a constant internal temperature

Endotherm: Animal that keeps internal temperature the same at all despite changes in external temperature

Which structure in the skin is involved in vasoconstriction

Arteriole

Describe the role of vasoconstriction in temperature regulation

• The muscles surrounding the arterioles contract.

• This reduces the blood flow into the near surface capillaries in certain parts of the body.

• This prevents heat loss in the skin

What structure is involved in piloerection?

Hair

Which structure is involved in both excretion and homeostasis. What is its product?

Sweat gland. Produces sweat, Water and salt.

Nam two other systems in which skin has a role

Immune and nervous

Give a biological reason why humans sweat during exercise

• Body increases in temperature

• We produce sweat which evaporates from our body’s heat

• This lowers our body’s temperature