Multicellular Organisms

single celled orgainism

can exchange substances directly with their environment

multicellular organism

have cells that don’t interact with the external environment and have a specialised internal environment which allows the exchange of vital substances between cells and the extracellular fluid that surrounds them

specialised cells

what are the 4 types of tissue in animals?

connective tissues, epithelial tissue, muscle tissue, nervous tissue

digestive system

the organs that take in food and liquids and break them down into substances that the body can use for energy, growth, and tissue repair

circulatory system

the system that transports blood, nutrients, gases, and waste products throughout the body.

vessels

that carry blood throughout the circulatory system, arteries, veins and capillaries

blood

is a type of connective tissue in animals, which transports nutrients and
oxygen to tissue cells for respiration, metabolism, and growth, as well as
transporting waste products to the excretory organs

erythrocytes

red blood cells

leukoytes

white blood cells

haemoglobin

a protein in red blood cells

platlets

cell fragments

open circulatory system

a type of circulatory system where blood is not always contained within vessels and bathes the organs directly.

what animals have an open circulatory system?

Arthropods including insects, crustaceans and most mollusks

haemolymph

circulates around the organs within the body cavity, reentering the heart through openings called ostia

ostia

openings in the heart that allow haemolymph to reenter after circulating around the organs.

closed circulatory system

there are 2 types the single and the double

single circualtory system

blood passes through the heart once only as it is pumped first through the gill capillaries, then the systemic capillaries in the organs and tissues, before returning to the heart.

double circulatory system

blood passes through the heart twice, as it completes two separate circuits or loops. The first loop carries deoxygenated blood to the lungs for oxygenation, while the second loop distributes oxygenated blood to the rest of the body.

what type of animals have a single circulatory system?

fish

what type of animals have a double circulatory system?

amphibians, reptiles, birds, mammals

pulmonary circuit

pumps deoxygenated blood to the lungs, where oxygen is absorbed and carbon dioxide expelled, and the blood is then returned directly to the heart.

systematic circuit

pumps the oxygenated blood out to the tissues and organs of the body, before returning the deoxygenated blood to the heart.

what circuit do amphibians have and why is it unique?

pulmocutaneos circulation because it brings deoxygenated blood to the surface for the gas exchange.

in mammals and birds what is the 2 circuits seperated by?

septum, dividing the heart into 2 seprate pumps

what does the septum in the mammalian heart also divide?

atrium and ventricle

atrium

collecting chamber

ventricle

pumping chamber

what does the right atrium do?

collects deoxygenated blood from the body

what does the right ventricle do?

pumps the deoxygenated blood into the lungs

what does the left atrium do?

collect oxygenated blood returning from the lungs

what does the left ventricle do?

pumps the oxygenated blood into the body

tricuspid and bicuspid (mitral) valves

prevent the back flow of blood between the ventricles and atria

pulmonary and aortic valves

prevent backflow between the major arteries and ventricles

pacemaker cells

control the timing within the heart

what do artieries do?

carry blood away from the heart

systole

the hearts contraction, sending blood out of the heart

diastole

when the heart relaxes and refills

what are capillaries?

are small, thin-walled blood vessels that branch out from arteries

capillary beds

maximise the contact between the blood vessels and the cells of the bodily tissues

capillary walls

are leaky and allow plasma to leave and mix with the interstitial fluid

what are in the capillaries?

blood cells and platelets

veins

collect the blood after it has passed through the capillaries and returns it to the heart

why do veins have thinner walls

the blood is under much lower pressure than in the arteries and contain one way valves that prevent back flow

cellular respiration

the process by which cells use oxygen to break down food molecules to create energy for life-sustaining activities

what does the exchange of gases require?

A semi-permeable membrane

A concentration gradient across the membrane
(diffusion occurs from areas of high concentration to areas of low concentration)

The membrane must be kept moist at all times

The membrane must have a high surface area relative to the volume of diffusion

insects gas exchange system

through a series of small pores called spiracles, which connect to an internal network of gas exchange surfaces called tracheoles.

fish gas exchange

are vertebrate animals that use gills to exchange gases with their water environment.

gills

have many folds and individual filaments which provide a large surface area for the exchange of gases.

how is the concentration gradient maintained in a fish?

is maintained by the flow of water in through the mouth and out through the gill slits, as well as the flow of blood through capillaries surrounding the gill filaments which carry oxygen to the body and return carbon dioxide to the water

mammals gas exchange

use lungs for the extraction of oxygen from air and the removal of carbon dioxide from the body

alveoli

greatly increase the surface area of the lungs and are composed of a thin layer of epithelial cells that are lined with a fluid that enables the rapid passive diffusion of gases into and out of the blood. Constant blood flow through the surrounding capillaries maintains a strong concentration gradient.

difference between fish and mammals gas exchange

Unlike in fish where water passes in one direction across the exchange surface, air must be constantly pulled in to the lungs, then pushed out again through a process called ventilation (breathing).

what are the 2 main stages of ventilation?

inspiration and expiration

inspiration

is the movement of air into the lungs

1. The intercostal muscles move the ribcage upwards and outwards causing the chest to expand.

2. The diaphragm contracts and flattens which increases the volume and decreases pressure inside the lungs

3. Air flows from the higher pressure of the environment into the lower pressure of the lungs.

expiration

 is the movement of air out of the lungs

1. The intercostal muscles move the ribcage downwards and inwards causing the chest to contract.

2. The diaphragm relaxes and moves upwards which decreases volume and increases pressure inside the lungs

3. Air flows from the high pressure inside the lungs to the lower pressure of the external environment.