Animal circulation, gas exchange, osmoregulation and excretion

Types of circulatory systems

Closed circulatory system

Open circulatory system

Example of organisms

Some molluscs

Arthropods

Fluid is HEMOLYMPH

Chemical exchange occurs between hemolymph and body cells

Advantages

Lower hydrostatic pressure

Less energy expenditure

Fluid is blood

Chemical exchange occurs between blood and the interstitial fluid, and between interstitial fluid and the body cells

Example of organisms

Advantages

Annelids, cephalopods, and all vertebrates

Relative high blood pressure

Well suited to regulating the distribution of blood to different organs

Single circulation

Bony fishes, rays and sharks have a heart consisting of 2 chambers: an atrium and a ventrical

Blood passes through the heart once in each complete circuit through the body

Double circulation

It has 2 circuit

For amphibians, reptiles, and mammals

Pulmonary circuit

It is the right side of the heart

It delivers oxygen poor blood to the capillary beds of the gas exchange tissues

Systemic circuit

It is the left side of the heart

It is where the oxygen rich blood goes after leaving the gas exchange tissues

Blood vessel

Capillaries

Smallest blood vessels

Their walls consist of just endothelium and basal lamina

Where gas are exchanged by diffusion between the blood and the interstitial fluid around cell tissues

Arteries

have 2 layers surrounding the endothelium

Their carry blood from the heart to organs

Outer layer- connective tissue

Inner layer- smooth muscle

Walls are thick, strong and elastic

Veins

walls are only about 1/3 as thick as that of an artery

Contain valves, which maintain a unidirectional flow of blood

have 2 layers surrounding the endothelium

Carry blood back to the heart

Inner layer- smooth muscle

Outer layer- connective tissue

Mammalian heart

Has 4 chambers

Has 2 ventricles

Has 2 atria

Serve as collection chambers for blood returning to the heart from lungs and other tissues

Pump blood throughout the body via the systemic circuit

Has 4 valves

2 atrioventricular valves

are between each atrium and ventricle

keep blood from flowing back into atria

Semilunar valves

keep blood from flowing back into the ventricle

Located at the 2 exists of the heart

one is where aorta leaves left ventricle

one is where pulmonary artery leaves the right ventricle

Blood

Osmosis is the movement of water through a semipermeable membrane from the hypotonic region to the hypertonic

Marine water animals

Most marine animals are osmoconformers; are isosmotic with its surroundings

Some marine animals are osmoregulators; they control internal osmolarity independent of that of the external environment

Marine water is strongly dehydrating environment

Fresh water animals

Fresh water animals face the problem of gaining water by osmosis and losing salts by diffusion

Few aquatic invertebrates that live in temporary ponds can lose almost all their body water and survive. This adaptation is called ANHYDROBIOSIS

Nitrogenous wastes

Ammonia

Most common in aquatic species

In many invertebrates, ammonia release occurs across the whole body surfaces

Urea

Most terrestrial animals and many marine species mainly excrete urea

In vertebrates, urea is the product of metabolic cycle that combines ammonia with CO2 in the liver

Advantage: low toxicity

Disadvantage: energy cost

Uric acid

Many reptiles, insects, land snails

Non toxic

Humans generate a small amount of uric acid from purine breakdown

Nephron

Cortical nephron

Juxtamedullary nephron

Reach only a short distance into the medulla

Extend deep into the medulla

Essential for the production of urine that is hyperosmotic to body fluids

Filtrate passes through 3 major regions of the nephron

Proximal tubule

Loop of Henle

Distal tubule

It is supplied with blood by an afferent arteriole

Major excretory organs

Urinary bladder

Urethra

Ureter

Kidney

Ureter, urinary bladder and urethra transport urine

Blood pressure

contraction of a heart ventricle generates blood pressure, which exerts force in all directions

Normal blood pressure is 120/70

Lymph circulation

By diffusion

Lymph nodes are lymph filter organs

Are fluid lost by capillaries

components

plasma is 55%

Water- solvent

Ions- blood electrolytes

are Na, Ca, Mg, Cl, K and bicarbonate

they function as buffer, maintain osmotic balance and regulate membrane permeability

Proteins

Immunoglobulins- defense

Albumin- maintain osmotic pressure and are pH buffer

Apolipoproteins- lipid transport

Fibrinogen- blood clotting

Cellular elements 45%

Substances transported by blood

Nutrients

Waste products of metabolism

Respiratory gases

Hormones

Platelets

Erythrocytes

Leukocytes

Breathing

Positive pressure breathing

Is a breathing in which air is forced into the lungs

negative pressure breathing

Air is pulled into the lungs

Diaphragm is a sheet of skeletal muscle that forms the bottom wall of the cavity

Mammalian respiratory system

Nostril- Nasal cavity- pharynx- larynx- trachea-lungs- bronchioles- alveoli

lined with mucus to trap pollens and cilia to move mucus

Gas exchange occurs in alveoli

Alveoli produce surfactant

Diverse excretory systems

Metanephridia

Malpighian

Protonephridia