Homostasis - Circulatory System Part 1 - 28 and 29 August 2012

Mechanism of Nutrition of Amoeba - Ingestion

The food is ingested at the point where it comes in touch with the cell surface with the help of pseudopodia. Pseudopodia engulf the food into the cytoplasm. The process of ingestion takes about 2 minutes.

Mechanism of Nutrition of Amoeba - Digestion and absorptionDigestion - Pseudopodia secretes a sticky and toxic fluid which adheres and kills the prey. It is then taken in by invagination to form a food vacuole whereby chemical digestion takes place.

Absorption - The food is converted into diffusible form and it is readily absorbed by the cytoplasm. The vacuole and becomes progressively smaller as the food is absorbed by diffusion.

 Mechanism of Nutrition of Amoeba - Assimilation and Egestion

Assimilation - These nutrients are used to build new protoplasm and to provide energy for the amoeba.

Egestion - The egestion takes place by exocytosis. There is no particular point from which the egestion takes place. As the amoeba moves forward, the undigested matter is shifted to the back and eliminated as food pellets through a temporary opening formed at any nearest point on the cell membrane. 

Transport in Humans 

Main transport system is called the Circulatory System. 

The Circulatory system works with 
1) the Respiratory system (Exchanges Carbon dioxide and Oxygen)
2) the Digestive system (Carries nutrients and wastes to/from the cells)
3) Works with the Excretory system (Carries waste to kidney for removal)

Human Circulatory System 

Consist of 
1) Cardiovascular System (Made up of Heart, Blood Vessels, Blood)
2) Lymphatic System (Made up of Lymph, Lymph nodes, Lymph vessels)

Cardiovascular System

Consists of 4 components 

1. Blood - The main 'transportation service' that handles the distribution of nutrients, oxugen and hormones to the various regions of the body.

2. Arteries and Veins - A system of tubes that form the transport route where blood flows.

3. Heart - The motor of this transport service.

4. Capillaries - are sites of exchange.

Divided into 

1. Pulmonary System and heart (Pulmonary = lungs)

2. Coronary System (Coronary = heart)

3. Systemic Circulation (Systemic = rest of body)

Double Circulation in Mammals 

Blood passes through the heart twice for each complete circuit of the body. 

Deoxygenated blood flows from the main circulation of the body to the heart, then to the lungs and oxygenated blood returned back to the heart (pulmonary circulation) before it is pumped into the main circulation and circulated to all parts of the body except the lungs (systematic circulation).