Animal tissues, organs and organ systems

2.2.1 The human digestive system

Balanced diet – right amount of nutrients & energy for needs

What is the function of digestive system?

An organ system in which several organs work tgt to digest & absorb food

Mouth	How can mouth break down starchy foods? Teeth break down food Saliva contains amylase
Salivary gland	Produce saliva containing amylase
Oesophagus	Muscular tube which move food to stomach
Stomach	Pummels food with muscular wall Produce protease, pepsin & HCl Gastric juice Water to moisten food HCl (pH2) to kill bacteria & help protease to work Pepsin to break proteins into amino acid Mucus to lubricate surface & protect from digestive enzyme & HCl
Bile (alkaline)	Made in liver & store in gall bladder Neutralise HCl from stomach to provide alkaline condition Emulsifies fats to break large lipid droplets into small droplets to ↑SA to ↑rate of fat breakdown by lipase
Small intestine	Digestion completed Absorb digested food & nutrients to blood Small molecules diffuse through villi walls into blood for respiration Adaptation Small intestine is very long, which gives plenty of time to complete absorption Villi are covered with microvilli, which increases SA to absorb quicker Villi contain blood capillaries, which provide rich blood supply to maintain a steep concentration gradient to assist quick absorption Villi have thin walls for short diffusion pathways into blood Have lots of mitochondria to provide energy from respiration Coeliac disease Damage villi ↓SA for absorption ↓ amino acid & glucose absorb ↓ amino acid available to build new tissues ↓ glucose ↓energy transfer from respiration
Large intestine	Absorb excess water from blood Form faeces
Rectum	Store faeces

Food chemistry

Carbohydrates

Use	Provide energy for metabolic reactions in cells in cellular respiration
Digestion	Starch → amylase → maltose + simple sugars
Made in	Salivary glands, pancreas & small intestine
Digestion sites	Mouth & small intestine

Proteins

Use	Build new tissues & cells Basis of cell enzymes
Digestion	protein → proteases → amino acids
Made in	Stomach, pancreas & small intestine
Digestion sites	Stomach & small intestine

Lipids

Use	To provide energy & insulation Forms part of cell membrane
Digestion	Lipids → lipases → fatty acids + glycerol
Made in	Pancreas & small intestine
Digestion sites	Small intestine

Biochemical test

Starch	Iodine solution (orange)	+ve black/blue -ve orange
Glucose	Benedict’s solution (blue) Boil 2 mins	+ve orange -ve blue
Protein	Biuret’s solution (blue) Shake	+ve purple -ve blue
Lipids	Ethanol Shake	+ve cloudy -ve clear

Enzyme

What are enzymes?

• Biological catalysts with a specific active site that increases rate of reaction

How do enzymes work?

‘Lock & key theory’

• Enzyme acts as lock, substrate acts as key
• Shape of substrate collides with active site of enzyme, which has a complementary shape to substrate
• If substrate fits into active site, they binds together, reaction happens quickly & substrate splits into products to be released
• After reaction, products leave active site & enzyme is ready to used again

Factors that affect the rate of reaction

Temperature	↑temp ↑ rate coz ↑KE, cells move faster, ↑ chance of collide active site of enzyme Optimum temp (37°C) – where enzyme work fastest High temp Causes protein chains to unravel changing the shape of active site of enzyme Active site no longer fit substrate’s shape Denatured
pH	Too low / high interferes with bonds holding enzyme together Change shape of enzyme’s active site Active site no longer fit substrate’s shape Denatured Optimum pH (pH8) Different part produce different pH Pepsin in stomach – pH2 Pancreatic amylase in duodenum – pH8

Calculation

2.2.2 The heart and blood vessels

Blood vessels

Arteries

Function	Transport oxygenated blood under high pressure from heart to organs of body
Adaptation	Thick walls – withstand high pressure Thick layers of elastic tissue – stretch & return to original shape Thick layer of muscle – maintain force on blood flow

Veins

Function	Transport deoxygenated blood under high pressure from organs of body to heart Low pressure coz long way & more friction reduces speed
Adaptation	Thin walls coz low pressure Large lumen help blood flow despite low pressure Have valves that close to prevent backflow of blood

Capillaries

Function	Transport blood to cells Form huge network of tiny vessels linking arties & veins
Adaptation	Thin permeable walls (1 cell thick) for short diffusion pathway Substances eg O2 to diffuse easily out of blood into cell Waste eg CO2 produced by cells diffuse easily into blood Narrow so blood cells pass through them one by one so more O2 released to tissues & taken up from lungs, more time available, shorter distance for exchange, more SA exposed

Calculation

2.2.3 Blood

Blood – a tissue consisting of plasma, in which the red blood cells, white blood cells & platelets are suspended

Blood contains…

Red blood cell

Function	Transport oxygen from lungs to all cells in body
Adaptation	Biconcave discs – increase SA to vol ratio for diffusion No nucleus – more space for haemoglobin & O2 Contain red pigment – haemoglobin In lungs, combines with O2 to form oxyhaemoglobin In body tissues, oxyhaemoglobin splits up into haemoglobin & O2 to release O2 to cell Small & flexible to fit through narrow blood vessals

White blood cell

Function	(See immune system) Defend body from infection by phagocytosis, produce antibodies & antitoxins
Adaptation	Have a nucleus to encode instructions for WBC to do their job

Platelets

Small fragments of cells produce by giant cells in bone marrow, don’t have nucleus

Function	Help blood to clot at wound by holding cells together to stop bleeding & microorganisms getting in
How?	Produce protein fibre o capture RBC & platelets to form clot, which plugs wound

Plasma – yellow liquid

Function

Transport blood cells & different substances around body RBC, WBC & platelets Nutrients eg glucose & amino acid CO2 from organs to lungs Urea from liver to kidney Hormones Antibodies & antitoxins produced by WBC

Uses of donated blood in medicine

• Replace blood lost from injury
• Given platelets to help clotting

Risk

• If different blood type, immune system reject blood & patient could die
• Diseases can be transmitted through blood

2.2.4 Coronary heart disease: a non-communicable disease

Heart

• An organ that pumps blood around the body in a double circulatory system
• Right ventricle pumps blood to lungs where gas exchange takes place
• Left ventricle pumps blood around the rest of the body

 

Aorta	Transport oxygenated blood under high pressure away from left ventricle of heart
Vena cava	Return deoxygenated blood from the body to right atrium of heart
Pulmonary artery	Transport deoxygenated blood from the heart to the lungs
Pulmonary vein	Transport oxygenated blood from the lungs to the heart
Valves	Close to prevent backflow of blood
Deoxygenated blood (right)	Organs → vein → vena cava → right atrium → right ventricle → pulmonary artery → lungs
Oxygenated blood (left)	Lungs → pulmonary vein → left atrium → left ventricle → aorta → artery → organs
Coronary arteries	Branch off aorta, surround heart Carry blood to heart Supply O2 & nutrients for heart to function If narrow/blocked – coronary heart disease

Why is muscle wall thicker on left ventricle?

• Allow left ventricle to develop pressure needed to force blood through arterial system all over body

Double Circulation

• Blood enters heart twice for one circuit around the body
• Efficient, pressure stay high so blood flows quickly

How is natural resting heart rate controlled?

• By a group of cells located in the right atrium that act as a pacemaker

Artificial pacemaker

• Electrical devices used to correct irregularities in the heart rate by sending electrical signals to heart

Cardiovascular diseases

Why do ppl have coronary heart disease eg cardiovascular diseases? (4)

• Layers of fatty material build up inside coronary arteries
• Narrow arteries
• Reduce blood flow
• Reduce O₂ supply for heart muscles

What symptoms do coronary heart disease have? (3)

• Pain, heart attack, fatal

What are the risk factors of cardiovascular diseases?

• Poor diet, smoking, lack of exercise

What are the treatments for coronary heart disease? (6)

Stents		Statins
Keep coronary arteries open Increase blood flow More O2 supply for heart muscles How? Metal mesh with balloon inside Balloon inflated to open stent & blood vessel Balloon deflated & removed but stent remains in place		Reduce blood cholesterol levels Slows down rate of fatty material deposit Reduce risk of develop heart attack
Advantages	Disadvantages	Advantages	Disadvantages
Effective in lower risk of heart attack Quick recovery time from surgery	Risk of heart attack or infection during operation Risk of blood clots form near stent	Reduce risk of heart attack Increase levels of HDL cholesterol	Produce side effects eg liver problems Need to take statins continuously

Faulty heart valves

Why do ppl have faulty heart valves? (3)

• Faulty heart valves prevent valve from opening fully
• Heart valves develop a leak
• Become breathless

What are the treatments for faulty heart valves? (6)

Biological valve		Mechanical valve
Valves taken from animals		Made of titanium/polymers
Advantages	Disadvantages	Advantages	Disadvantages
No medication Low risk of blood clot	Last for 10-20years Expensive	Last a lifetime Cheap	Increase risk of blood clots Take anticlotting drugs everyday for the rest of their life

Heart failure

Why do ppl have heart failure? (1)

• Heart can’t pump enough blood around body

What are the treatments for heart failure?  (6)

Heart transplant		Artificial heart
		Keep patients alive while waiting for heart transplant Allow heart to rest as aid to recovery
Advantages	Disadvantages	Advantages	Disadvantages
Only solution Better life quality after transplant	Hazards of operation Shortage of donors	Won’t reject by immune system Readily available	Increase risk of blood clots Increase risk of infection while operation

2.2.5 Health issues

Define health (1)

• State of physical & mental well-being

Define communicable disease (1)

• Caused by pathogens that can be passed from one person to another

Define non-communicable diseases (1)

• Cannot spread from one person to another

What causes ill health? (5)

• Communicable & non-communicable diseases
• Diet, stress & life situation eg accessibility to medical attention

Different types of diseases may interact

• Defects in immune system – more likely to suffer from infectious diseases
• Viruses living in cells – trigger for cancers
• Immune reaction initially caused by pathogen – trigger allergies eg skin rashes & asthma
• Severe physical ill health – metal illness eg depression

2.2.6 The effect of lifestyle on some non-communicable diseases

What are the effects of smoking? (4)

• Cardiovascular diseases – damage arteries lining, raise blood pressure, increase cholesterol
• Emphysema (lung diseases) – damage bronchioles & alveoli – shortness of breath
• Lung cancer – carcinogen causes mutation & uncontrolled growth of cells, damage cell lining in lungs
• Chemicals in smoke damage cilia – cause mucus production to increase – cause shortness of breath & increases risk of infection
• Reduce O₂ supply for unborn babies – cause health issues/death

Explain how a foetus may be affected if a mother smokes during pregnancy

The cigarette smoke will contain carbon monoxide which occupies the mothers red blood cells and so reduces the amount of oxygen that the mothers blood contains.  This means that the foetus receives less oxygen which reduces the rate of respiration in the foetus which causes the birth mass of the baby to be less.

What are the effects of alcohol? (3)

• Liver disease – damage liver cells when liver break down alcohol
• Affect brain function – damage nerve cells
• Damage unborn babies’ cells – affect development & cause health issues

Why are carcinogens, including ionising radiation, risk factors in cancer? (2)

• Damage cell’s DNA
• Makes cell divide uncontrollably

2.2.7 Cancer

Define cancer (1)

• Changes in cells that lead to uncontrolled growth & division
• Form tumour

Types of tumours

Benign tumours	Malignant tumours
Growths of abnormal cells Contained in one area, usually within membrane Do not invade other parts of body, not cancerous	Growths of abnormal cells Cells split up, invade neighbouring tissues & spread to other organs through blood Form secondary tumours in other organs