Transport in Animals

Question 1

what are reasons for transport systems in multicellular animals?

Answer 1

• small SA:V ratio so can’t rely on diffusion as substances won’t get to cells in the middle of the organism
• higher metabolic rate so diffusion wouldn’t be able to keep up with demand so transport systems are needed

Question 2

what are the main components of a transport system in animals?

Answer 2

• transport fluid in which substances are transported(e.g. blood)
• vessels through which the fluid can flow
• heart

Question 3

what are the two types of circulatory system?

Answer 3

open and closed circulatory system

Question 4

components of an open circulatory system?

Answer 4

consists of a heart that pumps fluid called haemolymph through short vessels and into a large capacity called the haemocoel. in the haemocoel the haemolymph directly bathes organs and tissues enabling the diffusion of substances. when the heart relaxes the haemolymph is sucked back in via pores called osita.
open circulatory systems have low pressure.

Question 5

components of a closed circulatory system?

Answer 5

blood is fully enclosed within blood vessels at all times. blood is pumped through vessels from the heart to capillaries around the body. and it has high pressure. the blood does not come directly into contact with the cells of the body. in a closed circulatory system, the transport fluid is enclosed within vessels at all times, whereas in an open one they are not always enclosed

Question 6

what are the two types of closed circulatory systems?

Answer 6

single and double

Question 7

What is a single closed circulatory system?

Answer 7

A circulatory system where blood flows through the heart once for each complete circulation of the body.

Question 8

What is an example of an organism with a single closed circulatory system, and how does it function efficiently?

Answer 8

Fish have a single closed circulatory system, with blood passing through capillaries in the gills for gas exchange before circulating through the body.

Question 9

How does a double closed circulatory system work?

Answer 9

Blood travels through the heart twice for each circuit – once to the lungs for oxygenation and once to the rest of the body.

Question 10

Why do mammals and birds require double circulatory systems?

Answer 10

they are endothermic and require high metabolic rates, so efficient oxygen and nutrient delivery are essential to maintain body temperature.

Question 11

Why do aquatic predators such as sharks rely on a single circulatory system?

Answer 11

Their gills efficiently extract oxygen from water, which allows them to maintain activity with a single circulatory loop.

Question 12

adv and dis adv of single circulatory system

Answer 12

adv:
- less complex so no need for complex organs
dis adv:
- Blood pressure drops as it passes through the gill capillaries, reducing the rate of flow to the rest of the body. so activity level of the animal tends to be low

Question 13

adv of double circulatory system

Answer 13

adv:
- It maintains a higher blood pressure and a faster flow of blood, enabling more efficient oxygen and nutrient delivery so allows organism to be more active.

Question 14

What are the key components of blood vessels and their functions?

Answer 14

Elastic fibres – Stretch/recoil, maintaining flexibility.
Smooth muscle – Contracts/relaxes to control lumen size.
Collagen – Provides structural support, maintains shape.

Question 15

What are the functions and structure of arteries and arterioles?

Answer 15

Function: Carry oxygenated blood away from the heart (except pulmonary & umbilical arteries).
Structure:

Thick walls with elastic fibers to handle pressure surges.
Smooth muscle controls diameter.
Collagen adds strength.
Arterioles are smaller arteries that control blood flow into capillaries.

Question 16

How do capillaries facilitate exchange of substances?

Answer 16

Capillaries are microscopic vessels linking arteries and veins.
Diameter: ~7.5μm, only one red blood cell wide.
Function:

Thin walls allow diffusion of substances.
Slow blood movement aids exchange.
Single endothelial cell layer for efficient diffusion.

Question 17

How do veins and venules return blood to the heart?

Answer 17

Function: Carry deoxygenated blood back to the heart (except pulmonary & umbilical veins).
Structure:

Thin walls with less muscle & elastic fibers.
Large lumen reduces resistance.
Valves prevent backflow.
Aiding Blood Flow:
Valves stop backflow.
Muscle contractions push blood upward.
Breathing movements create pressure changes that assist blood flow.

Question 18

What is an aneurysm, and why is it dangerous?

Answer 18

Definition: Weakening in a blood vessel wall, leading to bulging.
Common locations: Brain & aorta.
Risk factors: High blood pressure, genetic disorders.
Research findings:

Aortic aneurysms occur in 1.8-5.1% of humans.
Lung artery aneurysms occur in 9.7% of humans.
Implications: Helps predict individuals at risk

Question 19

What are the main components of blood and their functions?

Answer 19

Main Components:

Plasma – Carries nutrients, hormones, and proteins.
Red blood cells – Transport oxygen (contain hemoglobin).
White blood cells – Defend against infections.
Platelets – Help with blood clotting.
Blood Volume:

Plasma: 55% of blood.
Red blood cells: 45%.
White blood cells & platelets: <1%.

Question 20

How is tissue fluid formed, and what forces are involved?

Answer 20

Plasma leaks out of capillaries, forming tissue fluid.
Forces Involved:

Hydrostatic pressure pushes fluid out.
Osmotic pressure pulls fluid back in.
Fluid Return: 90% is reabsorbed into the blood, while 10% enters the lymph system.

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Question 21

What is lymph, and what does it do?

Answer 21

Definition: Tissue fluid that enters lymph capillaries.
Functions:

Returns excess fluid to blood circulation.
Contains white blood cells for immune defense.
Transports lipids from digestion.

Question 22

What is the function of the lymphatic system?

Answer 22

The lymphatic system plays a major role in fluid balance and immune defense by returning excess tissue fluid to the bloodstream and fighting infections.

Question 23

How is lymph formed?

Answer 23

Tissue fluid containing oxygen and nutrients is transported from the blood through the arteries to the capillaries.
Some tissue fluid is reabsorbed into the blood, while the rest drains into the lymphatic capillaries, forming lymph.

Question 24

How is lymph transported through the body?

Answer 24

Lymph capillaries join to form larger vessels.
Body muscle movement helps push lymph through the vessels.
One-way valves (like those in veins) prevent backflow.
Lymph eventually returns to the bloodstream via the right and left subclavian veins (under the collarbone).

Question 25

What are lymph nodes, and what do they do?

Answer 25

Lymph nodes contain lymphocytes that produce antibodies to fight infections.
They trap bacteria and debris, which are ingested by phagocytes.
They play a major role in the body’s defense mechanisms.

Question 26

Why do lymph nodes sometimes become enlarged?

Answer 26

Enlarged lymph nodes indicate that the body is fighting an infection.
They accumulate lymphocytes to help combat invading pathogens.
Doctors check lymph nodes in the neck, armpits, stomach, and groin to detect infections.