CDS 02 2021BIOLOGY CRASH COURSE

BLOOD

Blood is a special connective tissue consisting of a fluid

matrix, plasma, and formed elements

PLASMA➢Plasma is a straw coloured, viscous fluid constituting nearly 55 per cent of the blood

➢90-92 per cent of plasma is water and proteins contribute 6-8 per cent of it

➢Fibrinogen, globulins and albumins are the major proteins

➢Fibrinogens are needed for clotting or coagulation of blood

➢Globulins primarly are involved in defense mechanismsof the body and the albumins help in osmotic balance

➢Plasma also contains small amounts of minerals like Na+, Ca++, Mg++, HCO3 – , Cl– , etc. Glucose, amino acids, lipids, etc., are also present in the plasma as they are always in transit in the body

➢Factors for coagulation or clotting of blood are also present in the plasma in an inactive form

* Plasma without the clotting factors is called serum

FORMED ELEMENTSErythrocytes, leucocytes and

platelets are collectively called formed elements

RED BLOOD CELLS OR ERYTHROCYTES

◼Most abundant

◼Formed in red bone marrow

◼Devoid of nucleus

◼Biconcave

◼Red colour pigment - haemoglobin

◼Haemoglobin contains 4 iron

◼Average life span - 120days

◼Spleen- graveyard of RBCs◼ Disease - Anaemia

WHITE BLOOD CELLS/ LEUCOCYTES

◼Colourless i.e lack haemoglobin

◼Nucleated

◼Generally short lived

◼Two main categories

1. Granulocytes

2. Agranulocytes

Disease: leukemia

PLATELETS◼Also called thrombocytes

◼Involved in clotting & coagulation of blood

◼ Reduction in number leads to clotting disorders

◼Disease

1. Haemophilia

2. Dengue

3. Vitamin K

LYMPH➢Also called tissue fluid

➢Lymph is a colourless fluid containing specialised lymphocytes which are responsible for the immune responses of the body

➢Lymph is also an important carrier for nutrients, hormones, etc

➢Exchange of nutrients, gases, etc., between theblood and the cells always occur through thisfluid

➢An elaborate network of vessels called thelymphatic system collects this fluid and drains itback to the major veins

➢The fluid present in the lymphatic system iscalled the lymph

BLOOD GROUPSVarious types of grouping of blood has been done

Two such groupings –

I. the ABO grouping

II. Rh – grouping

are widely used all over the world.

CIRCULATORY PATHWAYSThe circulatory patterns are of two types – open or closed

A. Open circulatory system is present in arthropods and molluscs in which blood pumped by the heart passes through large vessels into open spaces or body cavities called sinuses

B. Annelids and chordates have a closed circulatory system in which the blood pumped by the heart is always circulated through a closed network of blood vessels

ALL VERTEBRATES

POSSESS A

MUSCULAR

CHAMBERED HEART

HUMAN CIRCULATORY SYSTEMHuman circulatory system, also called the

blood vascular system consists of a muscular chambered heart, a network of closed

branching blood vessels and blood, the fluid which is circulated

HEART➢Heart, the mesodermally derived organ, is situated in the thoracic cavity, in

between the two lungs, slightly tilted to the left

➢It has the size of a clenched fist

➢The entire heart is made of cardiac muscles

➢It is protected by a double walled membranous bag, pericardium, enclosing the pericardial fluid

1. CHAMBERS

2. VALVES

3. INTER- ATRIAL/

INTER VENTRIAL

SEPTUM

4. ATRIO-

VENTRICULAR

SEPTUM

5. SEMILUNAR VALVES

CORONARY CIRCULATIONCoronary circulation is the circulation of blood in the blood vessels that supply the heart muscles

Coronary Arteries are the arterial blood vessels of coronary circulation which transport O2 blood to the heart muscles ( wraps around the entire heart )

Coronary veins drains away the blood once it has been deoxygenated

THE TUBES – BLOOD VESSELS

➢VEINS

Veins collect the blood from different organs and bring it back to the heart. They do not need thick walls because the blood is no longer under pressure, instead they have

valves that ensure that the blood flows only in one direction

➢CAPILLARIESOn reaching an organ or tissue, the artery divides into smaller and

smaller vessels to bring the blood in contact with all the individual cells. The smallest vessels have walls which are one-

cell thick and are called capillaries. Exchange of material between the blood and surrounding cells takes place across this

thin wall. The capillaries then join together to form veins that convey the blood away from the organ or tissue

ELECTROCARDIOGRAPH (ECG)➢Machine (electro-cardiograph) is used to obtain an electrocardiogram (ECG)

➢ECG is a graphical representation of the electrical activity of the heart during a cardiac cycle

The biological process involved in the removal of these harmful metabolic wastes from the body is called excretion

FUNCTION OF EXCRETORY SYSTEM

Remove waste products and medicines from the body

01Balance the body's fluids

02Balance a variety of electrolytes

03

Unicellular organisms remove these wastes by

simple diffusion from the body surface into

the surrounding water

Complex multi-cellular organisms use

specialised organs to perform the same

function

The excretory system of human beings includes

• a pair of kidneys

• a pair of ureters

• a urinary bladder

• a urethra

Urine produced in the kidneys passes through the ureters into the urinary bladder where it is stored until it is released through the urethra

KIDNEY

Kidneys are located in the abdomen, one on either side of the backbone

Each kidney has nearly one million complex tubular structures called nephrons

NEPHRON

Structural & functional unit of kidney

Also called renal tubules or uriniferous tubule

Each nephron has two parts –

Glomerulus is a tuft of capillaries

The renal tubule begins with a double walled cup-like structure called

Bowman’s capsule, which encloses the glomerulus

Glomerulus along with Bowman’s capsule, is called the malpighian body or renal corpuscle

The tubule continues further to form a highly coiled network – proximal convoluted tubule (PCT)

A hairpin shaped Henle’s loop (U shaped ) is the next part of the tubule which has a descending and an ascending limb

➢The ascending limb continues as another highly coiled tubular region called distal convoluted tubule (DCT)

➢The DCTs of many nephrons open into a straight tube called collecting duct, many of which converge and open into the renal pelvis

URINE FORMATION

• Formed by

i. Glomerular filtration: Glomerulus

ii. Ultra-filtration: Bowman’s Capsule

iii. Reabsorption: reabsorption by the renal tubules

iv. Tubular secretion: tubular cells secrete substances like H+, K+ and ammonia into the filtrate, it helps in the maintenance of ionic and acid base balance of body fluids

It is a pale yellow coloured transparent fluid

Due to presence of pigment- Urochrome

Acidic nature

Heavier than water

Contains 95% water

The amount of the filtrate formed by the kidneys per minute is called glomerular filtration rate (GFR). GFR in a healthy individual is approximately 125 ml/minute, i.e., 180 litres per day

URETERS

These are a pair of narrow tube arising from the hilum of kidney

The urine forming in each kidney eventually enters a long tube, the ureter

They bring the urine downwards and open into urinary bladder

URINARY BLADDER

Medium- pear shaped sac

Situated in lower or pelvic region of abdominal cavity

Ureter opens into urinary bladder

Temporarily stores urine

*Absent in birds

URETHRA

Muscular and tubular structure

Extends from neck of bladder to outside

In females- tube is small and serves passage only for urine

In males- long tube as common passage for urine & spermatic fluids

Coordination is the process through which two or more organs interact and complement the functions of one another

The neural system provides an organised network of point-to-pointconnections for a quick coordination

NEURAL SYSTEMNeural system of all animals is composed of highly specialised cells called neuronswhich can detect, receive and transmit

different kinds of stimuli

HUMAN NEURAL SYSTEMThe human neural system is divided into two parts :(i) Central Neural System (CNS)(ii) Peripheral Neural System (PNS)

CENTRAL NEURAL SYSTEM (CNS)

◼Includes the brain and the spinal cord

◼Is the site of information processing and control

◼The brain is the central information processing organ of our body, and acts as the ‘command and control system’

PERIPHERAL NEURAL SYSTEM (PNS)

◼ Comprises of all the nerves of the body associated with the CNS

◼ The nerve fibres of the PNS are of two types:-

(a) Afferent fibres

(b) Efferent fibres

The afferent nerve fibres transmit impulses from tissues/organs to the CNS and the efferent nerve fibres transmit regulatory impulses from the CNS to the concerned peripheral tissues/organs

PNS is divided into two divisions

1. Somatic neural system: somatic neural system relays impulses from the CNS to skeletal muscles while the autonomic neural system transmits impulses from the CNS to the involuntary organs and smooth muscles of the body

2. Autonomic neural system: is further classified into sympathetic neural system and parasympathetic neural system

NEURON◼Neuron is a microscopic structure

◼Composed of three major parts:

a. Cell body

b. Dendrites

c. Axons

◼Neurons are excitable cells

GLA

ND

SGlands are important organs located throughout the body

They produce and release substances that perform certain functions

TYPES OF GLANDS

Exocrine glands

Endocrine glands

EXOCRINE GLANDS➢ Produce other substances — not hormones

➢Released through ducts to the exterior of your body, such as sweat, saliva, and tears

➢Play important roles in your body: regulate your body temperature, protect your skin and eyes, and even help mothers feed babies by producing breast milk

❖ Includes: salivary, sweat, mammary, sebaceous, lacrimal

ENDOCRINE GLANDS AND HORMONES

◼ Endocrine glands lack ducts

◼ Called ductless glands

◼ Their secretions are called hormones

Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts

Hormone as a chemical produced by endocrine glands and released into the blood and transported to a distantly located target organ

INHERITED TRAITS➢An inherited trait is one that is genetically determined

➢Inherited traits are passed from parent to offspring according to the rules of mendelian genetics

➢Most traits are not strictly determined by genes, but rather are influenced by both genes and environment

➢Examples: color of a person's hair, skin, and eyes, the blood group, the shape of nose and lips, and the tendancy to be short-sighted or to become bald

ACQUIRED TRAITS➢An acquired trait is the character developed in an

individual as a result of environmental influence

➢These traits are not coded by the DNA of a living organism and therefore cannot be passed on to future generations

➢Examples -Things you learned (riding a bike, reading, writing), scars from injury

KNOWN AS

FATHER OF

GENETICS

GREGOR JOHANN MENDEL

MONOHYBRID CROSS

INCOMPLETE DOMINANCE

CO-DOMINANCE

DIHYBRID CROSS

CHROMOSOMAL THEORY OF INHERITANCE

Walter Sutton & Theodore Boveri are credited with developing the Chromosomal Theory of Inheritance, which states that chromosomes carry the unit of heredity (genes)

MENDELIAN DISORDERS

Mainly determined by alteration or mutation in the single gene

Disorders are transmitted to the offspring

Pattern of inheritance can be traced in a family by the pedigree analysis

May be dominant or recessive

The trait may also be linked to the sex chromosome

Most common and prevalent mendelian disorders are haemophilia, cystic fibrosis, sickle cell anaemia, colour blindness, phenylketonuria, thalassemia, etc

1) Colour Blindness : sex-linked recessive disorder due to defect in either red or green cone of eye resulting in failure to discriminate between red and green colour

2) Haemophilia : sex linked recessive disease, which shows its transmission from unaffected carrier female to some of the male progeny

3) Sickle-cell anaemia : This is an autosome linked recessive trait that can be transmitted from parents to the offspring when both the partners are carrier for the gene (or heterozygous)

4) Phenylketonuria : This inborn error of metabolism is also inherited as the autosomal recessive trait. The affected individual lacks an enzyme that converts the amino acid phenylalanine into tyrosine

5) Thalassemia : This is also an autosome-linked recessive blood disease transmitted from parents to the offspring when both the partners are unaffected carrier for the gene (or heterozygous )

CHROMOSOMAL DISORDERS

Chromosomal disorders on the other hand are caused due to absence or excess or abnormal arrangement of one or more chromosomes

Failure of segregation of chromatids during cell division cycle results in the gain or loss of a chromosome(s), called aneuploidy

Failure of cytokinesis after telophase stage of cell division results in an increase in a whole set of chromosomes in an organism and, this phenomenon is known as polyploidy

1) DOWN’S SYNDROME : condition in which a child is born with an extra copy of their 21st chromosome — hence its other name, trisomy

2) KLINEFELTER’S SYNDROME : XXY is the set of symptoms that result from two or more X chromosomes in males

3) TURNER’S SYNDROME : that affects only females, results when one of the X chromosomes (sex chromosomes) is missing or partially missing

4) EDWARD’S SYNDROME: known as trisomy 18, is a genetic disorder caused by the presence of a third copy of all or part of chromosome 18

5) PATAU’S SYNDROME : caused by a chromosomal abnormality, in which some or all of the cells of the body contain extra genetic material from chromosome 13

ATAVISM

An atavism is a modification of a biological structure whereby an ancestral genetic trait reappears after having been lost through evolutionary change in previous generations

An atavism is a genetic trait that reoccurs after skipping several generations

VESTIGIAL ORGANS

Structures that have lost their use through evolution are called vestigial structures. They provide evidence for evolution because they suggest that an organism changed from using the structure to not using the structure, or using it for a different purpose

➢Sinuses. Human cheekbones hold the maxillary sinuses. ...

➢Appendix. It is one of the most commonly known vestigial organs. ...

➢Coccyx

➢Wisdom Tooth

➢External Ear

➢Nictitating Membrane

➢Tonsils

DIVERGENT EVOLUTION Forelimbs perform different functions in these animals, they have similar anatomical structure – hence, in these animals, the same structure developed along different directions due to adaptations to different needs

Homology indicates common ancestryHOMOLOGOUS ORGANS

Forelimbs perform different functions in these animals, they have similar anatomical structure – hence, in these animals, the same structure developed along different directions due to adaptations to different needs

Plants also, the thorn and tendrils of Bougainvillea and Cucurbita represent homology

CONVERGENT EVOLUTION They are not anatomically similar structures though they perform similar functions -- different structures evolving for the same function and hence having similarity

CONVERGENT EVOLUTIONSelection of similar adaptive features in different

groups of organisms but toward the same function

Sweet potato (root modification) and potato (stem modification) is another example for analogy

ADAPTIVE RADIATIONProcess of evolution of different species in a given geographical area starting from a point and literally radiating to other areas of geography (habitats) is called adaptive radiation

Natural Selection➢Nature selects for fitness➢Fitness is based on characteristics

which are inherited➢There must be a genetic basis for

getting selected and to evolve➢Some organisms are better

adapted to survive in an otherwise hostile environment➢Adaptive ability is inherited➢ It has a genetic basis➢Fitness is the end result of the

ability to adapt and get selected by nature

Darwin's Theory of Evolution by Natural Selection

SALTATION Single step large mutation

Idea of mutations –

large difference

arising suddenly in a

population

Mutations are random and directionless

Mutation caused

speciation

HUGO DE VRIES

HARDY-WEINBERG PRINCIPLE

This principle says that allele frequencies in a population are stable and is constant from generation to generation

The gene pool (total genes and their alleles in a population) remains a constant

This is called genetic equilibrium

Sum total of all the allelic frequencies is 1

p 2 + 2pq + q2 = 1

Five factors are known to affect Hardy-Weinberg equilibrium

Gene migration or gene flow

Genetic drift

Mutation

Genetic recombination

Natural selection

Sometimes the change in allele frequency is

so different in the new sample of population

that they become a different species. The

original drifted population becomes founders

and the effect is called founder effect