Life Science_ Term 3 & 4 (Pt. 1)

Circulatory System; Respiratory System; Excretory System

Circulatory system responsible for

• transporting blood with oxygen from lungs to cells
• transporting blood with carbon dioxide from the cells back to the lungs
• distributing nutrients from digestive system to cells in the body
• removing waste products to be excreted

Open blood circulatory system

When blood leaves the blood vessels and is pumped into the body cavity

Characteristics of an open blood circulatory system

• blood moves very slowly
• organism has low blood pressure
• restricted to smaller animals, like insects

Closed blood circulatory system

Blood remains within a system of blood vessels

Heart

• cone shaped organ
• strong cardiac muscle that pumps blood throughout the body
• contracts and relaxes continuously

4 Chambers of the heart

right atrium, right ventricle, left atrium, left ventricle

Pericardium

Protective connective tissue membrane enclosing the heart

• protects and anchors the heart to the surrounding organs

Location of the heart

Behind the sternum, between the lungs in the thoracic cavity

Path of deoxygenated blood

Deoxygenated blood → superior/inferior vena cava → right atrium → tricuspid valve → right ventricle → pulmonary valve → pulmonary artery → lungs

Path oxygenated blood

Oxygenated blood → pulmonary veins → left atrium → bicuspid valve → left ventricle → aortic valve → aorta → body

Purpose of septum

Keeps deoxygenated blood in the right atrium and ventricle separated from the oxygenated blood in the left atrium and ventricle

Why is the left ventricle thicker than the right?

It is responsible for pumping blood to throughout the whole body.

Arteries

Carry oxygenated blood away from the heart, to our body organs under high pressure

Veins

Carry deoxygenated blood to the heart

Capillaries

Lie very closely next to the cells of the body

Branch of blood vessels

Arteries → arterioles → capillaries → venules → veins

Constitution of blood

55% fluid plasma
Red blood cells
White blood cells
Blood platelets

Erythrocytes

• red blood cells
• biconcave discs
• average life cycle of 120 days

Hemoglobin

Oxygen carrying protein present in red blood cells
As red blood cells pass through the lungs, oxygen molecules attach to the hemoglobin

Leucocytes

• white blood cells
• microphages, T-cells, B-cells, plasma cells, memory cells
• important part of body's immune system

Thrombocytes

• blood platelets
• irregularly-shaped, colorless bodies present in blood
• play a role in clotting blood at the point of bleeding

Process of blood clotting

The platelets gather at the wound, they begin to form fibrin. The fibrin threads then begin to form a web-like mesh over the hole in the leaking blood vessel. This mesh traps the blood cells within it.

Pulmonary circulation

Short system that circulates blood between the lungs and heart

• part of the circulatory system

Systemic circulation

Longer system that circulates blood from the heart throughout the body and back again

• part of the circulatory system

High blood pressure

When the force with which the blood pushes against the walls of the blood vessels is too high and can cause damage to the capillaries and organs

• often results from eating too much salt

Heart attacks

When an artery narrows or a blood clot develops in one of the blood vessels that supplies the heart muscle with blood, it can stop the blood flow to the heart muscle and can stop it from pumping (heart attack)

Strokes

When cells in your brain are deprived of oxygen

• often occurs as a result of a blockage in the blood vessels leading to the brain, or when once of these vessels rupture

Diffusion

Movement of molecules from an area of higher concentration to an area of lower concentration.

Respiratory system

• deals with the exchange of gases in your body
• responsible for supplying the body's cells with oxygen and removing carbon dioxide

Path of oxygen in the respiratory system

mouth and nose → pharynx → larynx → trachea → bronchi → bronchioles → alveoli

Oxygen through the mouth and nose

Oxygen rich air enters the body through the mouth and nose where it is warmed by blood vessels which close to the surface of these openings

Air through the larynx

Inside the larynx are vocal chords, as the air is expired the vocal chord vibrate, allowing us to make sounds

Trachea

• tube that enters the chests and allows air to flow form the mouth into the bronchi
• kept open by cartilage rings
• splits into two air tubes (bronchi)

Epiglottis

Soft flap of tissue located just above the opening of the trachea which prevents food from entering

What happens when dust or germs enter the trachea?

The mucus lining the trachea traps the particles and the cilia on the ciliated cells work together to flick/move them out the body

Adaptions of alveoli

Thin wall to allow rapid gaseous exchange
Large surface area for rapid exchange of gases
Rich supply of blood vessels to transport gases to and from the gaseous exchange surface

Alveoli

The surfaces through which gaseous exchange occurs

• large air sacs
• found at the ends of bronchioles
• surrounded by capillaries

Lungs

• pink, spongy, air-filled structures
• surrounded by a protective membrane, pleura

Diaphragm

Dome shaped muscle below the lungs that enables you to breath

• main muscle used for breathing

Process of inhalation

Muscles between the ribs contract and lift it upwards
The diaphragm contracts; it flattens out
This increases the space in the chest and causes the pressure to drop
The low pressure causes air to be sucked into the lungs

Process of exhalation

Rib cage returns to its rest position
The diaphragm relaxes; it becomes dome-shaped
This decreases the space in the chest putting increased pressure on the air in the lungs, causing it to be pushed out

Breathing

Process of taking oxygen into the lungs and forcing carbon dioxide out the body

Locations of gaseous exchange within the body

• in the alveoli, oxygen diffuses into the blood from the alveoli and carbon dioxide diffuses from the blood back into the alveoli
• at the body tissue, oxygen diffuses from the blood into the cells and carbon dioxide from the cells diffuses into the blood

Cellular respiration

Metabolic reaction which occurs inside a mitochondria of a cell and results in the release of chemical energy

Common health issues of the respiratory system

Asthma, allergies that inflame the lung
Lung cancer, disease resulting from smoking/air pollution
Bronchitis, swelling of the lining of the bronchi due to infection
Pneumonia, alveoli fill with fluid due to infection
TB, infectious disease caused by bacteria

Excretion

The removal of toxic metabolic waste from the body so the internal environment can remain stable

Which metabolic waste accumulates in the body?

Excess mineral salts
Excess water
Nitrogen containing waste : ammonia, urea, uric acid
Non-nitrogenous wastes : nicotine, pain-killers, tranquillizers

Functions of the kidney

Filtration of blood
Excretion of metabolic wastes
Reabsorption of useful substances
Control the pH of the blood
Osmoregulation

Ureter

Tube that carries urine from kidney to bladder

Bladder

Stores urine

Sphincter/valve

Controls the release of urine from bladder

Urethra

Tube through which urine is released

Aorta (kidney)

Carries waste products, nutrients and oxygen from the heart to kidneys

Kidney

• acts as excretory organ
• bean shaped
• fit in between the rib cage and the pelvis, at the back of the body
• protected against heat loss and injury by masses of fatty tissue

Renal vein

Carries purified deoxygenated blood back to the inferior vena cava

Renal artery

Carries impure blood containing metabolic waste from the aorta to the kidney

• branches off the aorta

Nephron

Microscopic structure which carries out all the kidneys functions

Renal Capsule

Protects kidney

Cortex

Reddish outer area of kidney

Medulla

Light pink inner area of kidney

Kidney failure causes

Injury
Infection
Extensive use of certain drugs

Renal dialysis procedure

Blood from the artery is pumped into the dialyzer dialysis machine
The dialyzer cleans the blood by removing metabolic waste
The cleaned blood is then returned to the body

Disadvantages of renal dialysis

Treatment is time consuming
Patient may feel ill during treatment
Bleeding problems, due to the anticoagulants
Kidney machines are very expensive

Bladder infections

Bacteria and other micro-organisms get into the bladder

• most common in females; shorter urethra and closer to anus than men
• signs :
  smelly, cloudy urine
  burning sensation when urinating
• can be treated using antibiotics

Kidney stones

• hard crystals of calcium and salts form inside the kidney
• can block tubules and cause terrible pain
• most pass out of the body on their own, but others may have to be removed by surgery
• symptoms:
  sharp pain on the side of the body
  blood in urine

Disadvantages of kidney transplants

Difficult to find a suitable donor
Operation is expensive
Kidney can be rejected

Urinary systen