Chapter 8: Humans Flashcards
Specialisation
The adaptation of a cell, tissue, organ or system to carry out a special job is called specialisation
Divisions of labour
The seperate jobs carried out by the different parts of an organism is called division of labour
9 Human systems
- Digestive system
- Circulatory system
- Respiratory system
- Reproductive system
- Musculoskeletal system
- Nervous system
- Endocrine system
- Excretory system
- Immune system
The are two types of digestion
Physical digestion
Chemical digestion
Physical digestion
Food is broken down into smaller pieces by the teeth, tongue and churing action of the muscles in the stomach.
Chemical system
Food is broken down into smaller molecules by digestive enzymes and other digestive juices, including acid, in the stomach.
The 5 stages in Nutrition
- Ingestion: The food is taken into the mouth
- Digestion: The food is broken down into simpler, absorbable molecules
- Absorption: The absorbable molecules are passed into the blood and carried to all of the cells of the body
- Assimilation: The food is used by the body for energy and to build new cells.
- Egestion: Undigested food material is released from the digestive system as faeces.
Mouth
Food is ingested through the mouth
The teeth physically digest food and the enzymes in saliva chemically digest it.
There are four types of teeth
Salivary glands secrete saliva onto the food in the mouth. Saliva helps soften the food. Salivary amylase is the enzyme that chemically digests starch to maltose in the mouth.
Food is swallowed and enters the oesophagus (food pipe)
Oesophagus
Food is moved through the oesophagus by the wavelike movement of muscles. This continues the physical digestion of food.
Stomach
The stomach is an expandable muscular bag that physically churns and temporarily stores food.
The stomach releases juices that continue the chemical digestion of food.
Hydrochloric acid in the stomach chemically digests food and kills bacteria.
Small intestine
Food from the stomach enters the small intestine
More enzymes complete the breakdown of food.
The small intestine is densely covered in villi. The villi provide an increased surface area to allow food to be absorbed into the bloodstream.
Pancreas
Food does not travel through the pancreas. The pancreas produces digestive enzymes. These enzymes pass into the small intestine.
Liver
The liver is the largest internal organ in the body. It has many roles, including detoxifying alcohol and keeping to keep body temperatures at 37 degrees celcius.
Food does not pass through the liver. The liver produces bile. Bile passes into the small intestine, where it helps to digests fats.
Large intestine
Food from the small intestine enters the large intestine
The major role of the large intestine is to reabsorb water into the blood. It also prepares undigested food to be egested in the form of faeces
Rectum and anus
Faeces are temporarily stored in the rectum before egestion.
Faeces stimulate the rectum to contract and are passed out via the anus
The circulatory system has three main roles
Transport
Defence against disease
Homeostasis, including regulating body temperature
Blood
Blood is a tissue made up of plasma and three types of blood cells - red blood cells, white blood cells and platelets
Plasma
Is the liquid part of blood. It is mostly made of water
Plasma transports dissolved substances around the body, including oxygen, glucose, amino acids, hormones and anitbodies. It also carries wastes, such as carbon dioxide and urea.
Plasma carries heat around the body
It also carries the blood cells
Red blood cells
Transport oxygen to cells so that respiration can take place. They contain a red pigment called haemoglobin
White blood cells
Protect us from disease. They ‘eat’ harmful microorganisms or by producing anitbodies that kill them.
Platelets
Are tiny fragments of larger cells. They help the blood to clot. This helps to heal wounds, maintain blood pressure.
Learn the heat
Go do it!
Arteries
Carry blood away from the heart
Have thick walls to withstand the high pressure of blood pumped out of the heart.
The aorta is the major artery in the body. It branches out into a series of smaller arteries that deliver oxygenated blood and dissolved nutrients to all cells of the body.
Veins
Carry blood to the heart
Have thinner walls than arteries. The blood pressure in veins is lower than in arteries, so veins also have valves to prevent the backflow of blood
The venue cavae are the major veins. They carry deoxygenated blood, high in carbon dioxide, to the heart
Capillaries
Tiny blood vessels that link arteries and veins. There is a huge network of capillaries throughout the body.
The walls of capillaries are very thin so molecules can easily pass in and out of surrounding cells. The molecules exchanged include oxygen, carbon dioxide, glucose waste and hormones
How the heart pumps blood
- Blood with little oxygen and a high concentration of carbon dioxide enters the right atrium through the venae cavae
- Blood is then pumped from the right atrium through a cuspid valve and into the right ventricle
- The right ventricle contracts and forces blood up and out through a semilunar valve. The blood leaves the heart through the pulmonary artery
- The pulmonary artery delivers deoxgenated blood to the lungs. At the lungs, carbon dioxide is lost from the blood and oxygen is taken into the blood (gaseous exchange). The blood is now full oxygenated.
- The pulmonary vein brings oxygenated blood back to the left atrium
- Blood is pumped from the left atrium through a cuspid valve and into the left ventricle.
- The left ventricle contracts and forces blood up and out through a semilunar valve. The blood leaves the heart through the aorta and is distribute to all cells of the body.
- Exchange of molecules in the blood occurs at the capillaries. Capillaries reunite to form veins, which collect into venaw cavae that return to the right atrium. This completes one entire cycle.
The respiratory system has three main roles
- To take in oxyegn from the atmosphere
- To give out carbon dioxide and water into the atmosphere
- To make sounds, such as speech