(a) Mention different types of cell junctions present in epithelial tissue.
Epithelial cells are held together by specialized structures called cell junctions. The main types include:
(b) Differentiate between areolar and reticular connective tissue.
| Feature | Areolar Connective Tissue | Reticular Connective Tissue |
|---|---|---|
| Fiber Type | Contains Collagen, Elastic, and Reticular fibers. | Predominantly contains Reticular fibers (Type III collagen). |
| Function | Supports and binds other tissues; holds body fluids. | Forms a soft skeleton (stroma) to support lymphoid organs. |
| Location | Under the epithelia, surrounding capillaries. | Lymph nodes, bone marrow, and spleen. |
(c) Why is transitional epithelium also called urothelium?
Transitional epithelium is specifically referred to as urothelium because it is almost exclusively found in the urinary system.
It lines the urinary bladder, ureters, and parts of the urethra, providing the ability to stretch and recoil as the bladder fills and empties.
(a) What are the characteristic features of epithelial tissues? Explain the structure with diagram, location and functions of simple epithelial tissue. [2+8=10]
Characteristics of Epithelial Tissues:
Simple Epithelial Tissue:
Simple epithelium consists of a single layer of cells. It is classified into three types based on cell shape:
(b) Describe the structure and functions of adipose tissue. Add a note on dense connective tissue. [5+5=10]
Adipose Tissue:
Dense Connective Tissue:
Contains a high density of fibers (mostly collagen) with few cells. It is divided into:
(a) Mention the functions of plasma proteins.
(b) What is golden blood?
Golden blood refers to Rh-null blood type, which lacks all 61 possible antigens in the Rh system. It is extremely rare and considered a "universal" donor type for anyone with rare Rh blood types.
(c) Mention the functions of cartilage.
(a) Describe the structure of a compact bone with suitable illustrations. Differentiate between red and yellow bone marrow. [8+2=10]
Structure of Compact Bone:
Bone Marrow Differentiation:
(b) Write short notes on: (i) Structure and function of hemoglobin (ii) Bicarbonate buffer system of blood. [5+5=10]
(i) Hemoglobin:
A globular protein in RBCs consisting of four polypeptide chains (two alpha, two beta), each with a heme group containing an iron atom. Its function is to transport oxygen from lungs to tissues and CO2 from tissues to lungs.(ii) Bicarbonate Buffer:
A critical system maintaining blood pH (~7.4).CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3-It prevents drastic changes in acidity by neutralizing excess acids or bases.
(a) Enlist the locations of smooth muscles in the body.
(b) What is meant by summation in context of muscle contraction?
Summation is the addition of individual muscle twitch contractions to increase the overall intensity of muscle contraction, occurring when stimuli are applied in rapid succession.
(c) What is muscle treppe?
Also known as the "staircase effect," treppe is the gradual increase in muscular contraction strength following rapidly repeated stimulation of the same intensity.
(a) Describe the ultrastructure of skeletal muscle with suitable diagram. How does striated muscle differ from non-striated? [8+2=10]
Ultrastructure:
Skeletal muscle is made of myofibrils which contain sarcomeres (the functional unit). Sarcomeres consist of thick filaments (myosin) and thin filaments (actin). Features include Z-discs, I-bands (light), and A-bands (dark).Striated vs. Non-striated: Striated muscles (Skeletal/Cardiac) show visible banding patterns under a microscope due to sarcomere arrangement, whereas non-striated (Smooth) muscles lack these bands.
(b) Describe the molecular and chemical bases of muscle contraction with suitable diagrams. [10]
This process follows the Sliding Filament Theory:
(a) What is the neuron doctrine?
The concept that the nervous system is made up of discrete, individual cells (neurons) rather than a continuous network.
(b) Mention the criteria used for the classification of nerve fibres.
(c) Glial cells forming myelin sheath:
(a) Describe the structure of a myelinated neuron with a neat labelled diagram. Add a note on the properties of nerve fibres. [7+3=10]
Structure:
Consists of a cell body (Soma), Dendrites (receive signals), and an Axon (conducts impulses). In myelinated neurons, the axon is covered by a Myelin Sheath with gaps called Nodes of Ranvier.Properties:
Excitability, Conductivity, All-or-none law, and Refractory period.(b) Write a note on synaptic transmission with diagram. Add a note on neuromuscular function. [7+3=10]
Synaptic Transmission:
An impulse reaches the presynaptic terminal, causing the release of neurotransmitters (e.g., Acetylcholine) into the synaptic cleft. These bind to receptors on the postsynaptic membrane to trigger a new impulse.(a) Islets of Langerhans cell functions:
(b) What is Kupffer cell? State its function.
Specialized macrophages located in the liver lining the sinusoids. Their function is to recycle old RBCs and destroy pathogens/debris from the blood.
(c) What are alveoli? Functions:
Tiny air sacs in the lungs where gas exchange occurs. Function: To exchange Oxygen and Carbon dioxide between the air and the blood.
(a) Describe the structural and functional unit of kidney with suitable diagram. Write a note on different functions performed by kidney. [6+4=10]
Nephron Structure:
Composed of the Renal Corpuscle (Glomerulus + Bowman's Capsule) and Renal Tubule (PCT, Loop of Henle, DCT, and Collecting Duct).Functions of Kidney:
Excretion of waste (urea), Regulation of blood pressure, Maintenance of electrolyte balance, and Erythropoietin production.(b) Write short notes on: (i) Histology of liver (ii) Histology of blood vessels. [5x2=10]
(i) Histology of Liver:
Organized into hexagonal lobules. Each lobule has a central vein and portal triads (bile duct, hepatic artery, portal vein) at corners. Hepatocytes are arranged in plates separated by sinusoids.(ii) Histology of Blood Vessels:
Consists of three layers: Tunica intima (innermost endothelium), Tunica media (smooth muscle/elastic fibers), and Tunica externa (connective tissue).