Presentation Unit 3

BIOLOGY AND GEOLOGY 3º DE E.S.O.

Chapter 3:

1. Explain what each one of the arrows represents.

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1 THE DIGESTIVE SYSTEM

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watch?v=_l8aLmomDPU

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Introduction

The digestive

system is used for

breaking down food

into nutrients which

then pass into the

circulatory system

and are taken to

where they are

Gastric glands:Secrete gastric juice and protective mucus Intestinal glands:

• http://www.edistribucion.es/anayaeducacion/8440042/U03_SC3/02_Digestive%20system/La_digestion_ingles/laDigestion.html

2 DIGESTION PROCESS

Introduction

Digestion

can be

considered as a

series of steps:

1. Physical or

mechanical

digestion

2.Chemical digestion

3. Absorption

Chewing

In this step teeth are used to

break down food into small pieces by cutting, tearing, crushing and grinding it. The

tongue mixes saliva with the food and forms a bolus

of food. That is a conscious

act using voluntary muscles.

•

The rest of the process is

automatic.

•

_{Thanks to the}

_peristaltic

activity, the

bolus

of

food passes down the

pharynx

, through the

oesophagus,

not down

the trachea!,

and into the

stomach

.

•

_{The bolus passes}

down the

esophagus by

peristalsis.

•

_{Peristalsis is a wave}

of muscular

contractions that

push the bolus

down towards the

stomach.

2.2 CHEMICAL DIGESTION

•

_Saliva

_{, elaborated by}

the

parotid glands

,

the

submandibular

glands

, and the

s

ublingual glands,

contains

amylase

and

maltase

which break

down the

c

arbohydrates

,

•

_{To enter the}

stomach

, the bolus

must pass through

the lower

esophageal

sphincter (cardia), a

muscle that keeps

stomach acid out of

the esophagus

.

•

_{The stomach Cells}

which lined the

inner

wall

of the stomach

produce

gastric

juices

. These juices

contain

proteases

(enzymes)which

break down

proteins

,

and

hydrochloric

acid

(

HCl

).

•

The

acid

kills off any

invading bacteria or

viruses.

•

The

enzymes

help break

down proteins. Chemical

Digestion.

•

_The

_mucus

_{protects the}

lining of the stomach

from being eaten away

by the acid.

•

_{The digested bolus is}

now called

chyme

and it

leaves the stomach by

passing through the

pyloric sphincter

.

• Thanks to the intestinal

juices, the bile, produced by the liver, and the pancreatic juices, the digestion of food is completed.

• The bile helps to digest the fats by emulsifying it into minute droplets.

• The intestinal and

pancreatic juices finish the chemical digestion (proteins, fats and carbohydrates) .

• A whitish liquid paste is

formed, called chyle, which contains water, nutrientsas the result of the digestion, and other non digested remains.

2.3 ABSORTINON OF NUTRIENTS

• The result of the digestion is to obtain nutrients, which are small enough to go through the walls of the digestive

tract and pass into the blood. This process is called

absorption.

• It is in the small intestine

where a major part of

The walls of the

intestine

contain

veins

and

capillaries

which absorb the

nutrients into the

bloodstream

and

then into all the cells

of the body.

•Most of substances are absorbed in the jejunum (mainly) and

ileum.

•In these parts, the inner wall of the small intestine is much folded

making up the intestinal villi.

•In the inner part of the intestinal

villi there are capillary vessels

(small blood vessels) and

lymphatic vessels which take away the nutrients.

•Then they are delivered to all the cells of the body.

•

_{Each villi itself has tiny fingerlike}

projections called microvilli, which

further increase the surface area for

absorption

.

The

capillary vessels

take

away

simple sugars

and

amino acids

, and carry them

to the

liver

via the

portal

vein

.

The

lymphatic vessels

transport the

fatty acids

and

glycerol

around the body and

finally release them into the

bloodstream

.

•

_{The large intestine}

is used to absorb

water from the

waste material

leftover and to

produce vitamin K

and some B

vitamins using the

helpful bacteria that

live here.

•

_{All leftover waste is}

compacted and stored

at the end of the large

intestine called the

rectum.

•

_{When full, the anal}

sphincter loosens and

the waste, called

feces, passes out of

the body through the

anus.

3. The respiratory system

We breathe using the respiratory system

We obtain oxygen from the air

We expel the CO₂

3.2 How does the respiratory

system work

Breathing has three phases:

Inhalation

Gas exchange

3.2 How does the respiratory system

During Inhaling, the brain sends electric impulses by nerves to the diaphragm and the inter costal muscles.

The diaphragm contracts becoming flatter.

The inter costal muscles also contract.

These actions expand the thoracic cavity and increase the volume, with the volume increasing the internal pressure decreases which makes air enter the lungs through the mouth, nose and trachea.

During Exhaling, the diaphragm and the inter costal muscles relax again, contracting the thoracic cavity thus squeezing the air out of the lungs to the trachea and mouth and nose to the atmosphere

3.2 How does the respiratory system

work:

Inhalation and exhalation

3.2 How does the respiratory system

work: gas exchange

4. The circulatory system

The circulatory system transport nutrients, oxygen, CO₂ and waste around the body.

4.1 Blood Vessels

–Arteriesmove the blood away from the heart to the cells Elastic Fibers

Thick outer wall

–Capillaries – where gas exchange takes place. Very thin outer wall

Connect all the cell in our body

–Veinsmoves the blood towards the heart

Skeletal Muscles contract to force blood back from legs Thin outer wall

One way valves

4.2 The blood

4.2 The blood

A.

Plasma

•

Liquid portion of the

blood. Contains

4.2 The Blood

Blood cells

a) Erythrocytes - Red

Blood Cells

Carry hemoglobin and oxygen and carbon

dioxide. Do not have a

nucleus and live only about 120 days.

4.2 The Blood

•

Blood cells

b) Leukocytes – White Blood

cells

Fight infection

4.2 The Blood

•

The Blood cells

•

C). Thrombocytes –

Platelets.

–These are cell fragment that are formed in the bone marrow.

4.3 The heart

The Heart

Cardiac muscle tissue

The cardiac muscle contracts and relaxes 60-80 time per minute (heartbeat)

Four parts

•Right atrium

•Right ventricle

•Left atrium

•Left ventricle

4.4 Cardiac Cycle

•

Heart is two pumps that work together, right

and left half

•

Repetitive contraction (systole) and relaxation

(diastole) of heart chambers

•

Blood moves through circulatory system from

areas of higher to lower pressure.

4.4 Cardiac Cycle

Heart Sounds

•

First heart sound or “lubb”

– Atrioventricular valves and surrounding fluid

vibrates as valves close at beginning of ventricular systole

•

Second heart sound or “dupp”

5 BLOOD CIRCULATION

The pulmonary circulation transports blood poor in oxygen from the heart to the lungs and then returns

rich in oxygen

The systemic

circulation transports blood rich in oxygen from the heart to the cells and then returns

poor in oxygen

6. The lymphatic system and

the internal medium

All cells of the body are bathed in fluid called intercellular or intersticial plasma (tissue fluid).

The composition of the intersticial plasma must remain constant. The lymphatic system develop this function

6. 1 The internal medium

Intercellular fluid contains: water, proteins, wastes, salts and nutrients

It helps to move materials between capillaries and body cells

Exchange of materials occurs through this fluid

Lymphatic system is composed of:

lymph

lymph vessels

lymph capillaries

lymph nodes (contain

lymphocytes and macrophages)

lymph organs/glands: spleen, tonsils, thymus

6.2 Lymphatic System

The lymphatic system

Collects excess large

particles and fluid

Collects digested fats

Spleen:

-

- filters out old red

blood cells from blood

Thymus:

- located in the middle of the chest

- provide growth and immunity

- gets smaller when the organism gets older

- secretes thymosin (helps lymphocytes to become mature)

Lymphatic capillaries are tiny vessels of the lymphatic system.

 Near each cell there are

lymph capillaries that made up

lymph vessels.

When water and proteins enter lymph capillaries they are called lymph.

 Lymph capillaries are made up of epithelial cells, they are more permeable than blood capillaries.

Lymph nodes

- play role in body

defense against disease

- produces lymphocytes

Tonsils:

trap and destroy bacteria

The lymphatic system

does not have pumping

organ

Uses the same methods

as veins to propel lymph:

Pulsations of nearby

arteries

Contractions of muscle in

the walls of the lymphatics

Valves are present to

prevent back flow

7. The excretory system

The excretion is the elimination of wastes from the

cell activities

This wastes are

eliminated

through lungs,

skin, and the

excretory

system.

Lungs exhale

carbon dioxide

and water vapor.

Sweat glands in

skin release

The principal function of

the kidney is to filter

blood in order to

remove cellular waste

products from the body.

7. The excretory system

The kidneys are bean

shaped structures.

•

three layers: cortex,

medulla and pelvis

•

filtering units called

nephrons

•

_{renal artery and renal}

vein

The kidney can excrete waste products, such as :

1)

urea

a nitrogenous waste produced in the liver

from the breakdown of protein. It is the main

component of urine

2)

uric acid

usually produced from breakdown of

DNA or RNA

3)

creatinine

waste product of muscle action.

• The ureters are tubes that carry urine from the pelvis of the kidneys to the urinary bladder.

• _{The urinary bladder}

temporarily stores urine until it is released from the body.

• The urethra is the tube that carries urine from the

urinary bladder to the outside of the body.

• The outer end of the

7.2 The excretory system: urine

•

_Nephrons

_{are the}

filtering units in the

kidneys.

•

They clean and

rebalance the blood

to produce urine.

•

There

approximately 1

million nephrons in

each kidney

from body

to body

To ureter

• The body’s entire volume of blood is filtered every 45 min

FILTRATION

Water, electrolytes, amino acids,

glucose, urea, and other small

molecules diffuse out of the blood, creating the filtrate.

1

• Nephrons clean the blood in a three-step process.

• The first step is filtration of the blood.

• Glomerulus: Network of capillaries • Bowman’s Capsule: Encases the glomerulus

• The first step is filtration of the blood.

• The second step is reabsorption of materials.

REABSORPTION

As the filtrate enters the rest of the tubule, most of the materials are reabsorbed into the blood. Materials not reabsorbed make up the urine, which flows into the loop of Henle. 2 from body to body collecting duct from other nephrons loop of Henle

• The first step is filtration of the blood.

• The second step is reabsorption of materials.

• The third step is excretion of materials.

from body to body collecting duct from other nephrons loop of Henle

EXCRETION

In the loop of Henle, water can be

reabsorbed one final time to reduce the volume of urine. The remaining urine flows into a collecting duct that leads to the ureter.

3

· The

sweat glands

which expel the waste in form

of

sweat

.

· The

lungs

which expel the waste in form of

carbon dioxide

.

· The

liver

which expels the waste in form of

cellular rest

.