⭕️Endoplasmic Reticulum⭕️

(1) Definition: It is well developed electron microscopic network of interconnected cisternae, tubules and vesicles present throughout the cytoplasm, especially in the endoplasm.

(2) Discovery: Garnier (1897) was first to observe the ergastoplasm in a cell. The ER was first noted by Porter, Claude, and Fullman in 1945 as a network. It was named by Porter in 1953.

Golgi Complex
(1) Definition: Golgi complex is made up of various membranous system e.g. cisternae, vesicles and vacuoles.

(2) These are also called golgi bodies, golgisomes, lipochondrion, dictyosomes, Dalton complex, idiosomes or Baker’s body.

(3) These are also called “traffic police” of the cell.

(4) Discovery: First observed by George (1867) but it’s morphological details were given by Camillo Golgi (1898), in nerve cells of barn fowl and cat .

Fig.: A diagram of a section of an alveolus with a pulmonary capillary

𝗘𝗫𝗖𝗛𝗔𝗡𝗚𝗘 𝗢𝗙 𝗚𝗔𝗦𝗘𝗦

Alveoli are the primary sites of exchange of gases.

Gaseous Exchange in Lungs

● At alveoli level, gaseous exchange occur through respiratory membrane (diffusion membrane) which is 0.2 mm thick (total thickness is much less than a mm).

● 𝗜𝘁 𝗰𝗼𝗻𝘀𝗶𝘀𝘁 𝗼𝗳 𝘁𝗵𝗿𝗲𝗲 𝗹𝗮𝘆𝗲𝗿𝘀:

(i) Alveolar epithelium (thin squamous epithelium)

(ii) Basement substance in between them (composed of a thin basement membrane supporting the squamous epithelium and the basement membrane surrounding the single layer endothelial cells of capillaries)

(iii) Endothelium of alveolar blood capillaries

● Exchange of gases also occur between blood and tissues.

● O2 and CO2 are exchanged in these sites by simple diffusion mainly based on pressure/concentration gradient

● Pressure contributed by an individual gas in a mixture of gases is called partial pressure and is represented as pO2 for oxygen and pCO2 for carbon dioxide.

𝐌𝐄𝐓𝐀𝐁𝐎𝐋𝐈𝐓𝐄𝐒 --------------------

✤ Biomolecules in our body are called ‘metabolites’ as they
are involved in the metabolic reactions (catabolism and
anabolism).

✤ Metabolites are the products and intermediates of cellular
metabolism. Metabolites can have a multitude of functions,
including energy conversion, signaling, epigenetic influence,
and cofactor activity.

𝗧𝗬𝗣𝗘𝗦 𝗢𝗙 𝗠𝗘𝗧𝗔𝗕𝗢𝗟𝗜𝗧𝗘𝗦

(i) Primary Metabolites

✤ Involved in the primary metabolism of body (Respiration, amino acid metabolism, nucleotide metabolism etc.).


✤ They have identifiable functions and play known roles in normal physiological processes. e.g. amino acids, sugars, phospholipids, glycerol, cholesterol, nitrogenous bases etc.

✤ It is present through out the plant kingdom.(ii) Secondary Metabolites

✤ They are typically organic compounds produced in plant,
fungal and microbial cells.
They do not play a direct role in growth and development.

E.g. alkaloids, flavonoids, rubber, essential oils, antibiotics, coloured pigments, scents, gums, spices, drugs.

✤ Many of secondary metabolites are useful to ‘human welfare’
Some secondary metabolites have ecological importance.

TYPES OF CARTILAGE:

♦️ Hyaline Cartilage: This type of cartilage has a glassy appearance. It is the weakest of the all types of cartilage. It is found in the ribs, septum of nose, larynx, and trachea.

♦️ Fibrous Cartilage: This type of cartilage has opaque matrix. This is the strongest kind of cartilage, because it has alternating layers of hyaline cartilage matrix and thick layers of dense collagen fibres. E.g. intervertebral disc.

♦️ Elastic Cartilage: It has opaque matrix. In elastic cartilage, the chondrocytes are found in a thread like network of elastic fibres within the matrix. Elastic cartilage provides flexibility, strength, elasticity, and maintains the shape of certain structure. E.g. tip of nose, ear pinna.


♦️ Calcified Cartilage: It has opaque matrix. Calcified cartilages are formed due to the deposition of calcium in the matrix of the cartilages. It is the hardest form of cartilage.

Types of Neurons on Basis of Number of Processes:

♦️ Neurons can be differentiated as unipolar, bipolar or multipolar depending upon the number of processes arising from the cell body.

♦️ UNIPOLAR NEURON: Unipolar neuron has one nerve process extending from the cell body (an axon that extends into dendrites). Unipolar neurons only occur in invertebrates.

♦️ BIPOLAR NEURON: Bipolar neuron is a type of neuron that has two extensions (one axon and one dendrite). They are sensory neurons found in olfactory epithelium, the 39
of the eye.

♦️ MULTIPOLAR NEURON: Multipolar neuron is a type of neuron that possesses a single axon and many dendrites They are located in the central nervous system (brain and spinal cord)

Notes for the Day ✌️

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❁  The fruit develops a thick wall called pericarp that is protective in function.🔥

❁ After dispersal, seeds🌱 germinate under favourable conditions to produce new plants. 🌾

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