Anatomy and Physiology of Animals/Glossary/Q,R,S

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Word Meaning
R
Radius The shorter bone of the forelimb between the humerus and the “wrist”
Receptor A specialized cell that responds to specific sensory stimuli such as touch,pressure, light etc.
Red marrow Bone marrow found in the spaces of spongy bone.Makes red blood cells
Reflex A fast automatic response to a stimulus
Reflex arc Consists of receptor, sensory, relay and motor neurons and effector
Refraction Bending of light as it passes from one medium to another
Relaxin The hormone secreted by the placenta and ovaries that eases the joint between the right and left pelvis

and dilates the cervix for birth

Renal To do with the kidney
Renal pelvis The cavity in the centre of the kidney
Renal pyramid A cone shaped structure in kidney medulla
Renal system The body system involving the kidneys
Reticulum The part of the modified stomach of ruminants with honeycomb of raised folds on its inner surface
Retina The inner coat of the eyeball. Nerve calls here (rods and cones} respond to light ray
Ribosome The organelle in the cell that makes proteins
Rickets A bone disorder caused by inadequate vitamin D
Rod The photoreceptor in the retina, specialized for vision in dim light
Rostral Towards the muzzle
Rumen The first and largest compartment of the modified stomach of ruminants.It houses the microorganisms
Ruminant An animal with a rumen e.g. sheep, cow, camel
Rumination Chewing the “cud”
S
Sacrum The triangular bone formed from fused sacral vertebrae.Located between the two hipbones
Sagittal plane Plane that divides the body into left and right portions
Sagittal section Lengthwise slice of an animal or organ
Saliva The secretion from the salivary glands
Salivary amylase The starch digesting enzyme in saliva
Saturated fat A fat containing saturated fatty acids
Scapula The shoulder blade
Sciatic nerve The large nerve that passes down the hind leg
Sclera The fibrous outer coat of eyeball
Seasonal breeding Breeding confined to certain seasons of the year
Sebaceous gland An exocrine gland in the dermis of the skin associated with a hair follicle
Sebum The waxy secretion from a sebaceous gland
Secondary sex characteristic A characteristic that develops at sexual maturity. e.g. large body size of males, manes in lions
Secretion The production or release of a fluid from a gland
Semen The fluid discharged at ejaculation of male. Consists of sperm and fluid
Semicircular canals The membranous fluid filled canals containing receptors for equilibrium
Semilunar valve The valve guarding the entrance to the aorta or the pulmonary artery
Seminal vesicle A gland that secretes a component of semen
Seminiferous tubule The tightly coiled duct in the testis where sperm are produced
Semi-permeable membrane A membrane that allows some substances to cross more easily than others
Sensory neuron A neuron that carries a nerve impulse towards the central nervous system
Serum Plasma minus its clotting proteins
Sesamoid bones Small bones usually found in tendons
Shock Reduced cardiac output resulting in failure to deliver adequate oxygen and nutrients to the body
Shoulder The synovial joint where the humerus joins the scapula
Sinus An air cavity in a bone especially in the bones of the face or skull
Skeletal muscle Tissue specialized for contraction with striated fibres. Attached to the bones of the skeleton
Skull The skeleton of the head
Small intestine The long tube of the gut that begins at the stomach and ends at the large intestine
Smooth muscle Tissue specialized for contraction with spindle shaped non striated fibres
Soft palate The posterior portion of the roof of the mouth
Solution One or more substances dissolved in a liquid
Specific gravity A measure of the density of a liquid or solid, as compared with that of water.
Sperm duct The tube that carries sperm from the epididymis to the urethra. Also called the vas deferens
Spermatic cord The structure in the male reproductive system attached to the testis that carries the vas deferens, arteries, veins, etc.
Spermatozoon A mature sperm cell
Sphincter A ring-like muscle that controls movement along a body passage or orifice
Spinal cord The mass of nerve tissue in the vertebral column
Spinal nerve One of the nerves that originate in the spinal cord
Spleen The large lymphatic organ near the stomach that stores blood and produces lymphocytes
Spongy bone The inner layer of bone; found at the ends of long bones less dense than compact bone
Squamous Scale like
Starch The storage polysaccharide in plants consisting of many glucose molecules
Sterile Free from any living micro organisms
Sternum The breastbone
Stifle The joint between the femur and the tibia on the hind leg
Stimulus Any change in the environment capable of initiating a nerve impulse
Stomach The large baglike part of the gut between the oesophagus and the small intestine
Striated muscle Striped or skeletal muscle
Subcutaneous Beneath the skin
Submandibular gland The salivary gland beneath the tongue
Substrate A substance on which an enzyme acts
Sulcus A groove or depression between the convolutions of the brain
Superficial Nearer to the surface of
Suture An immoveable joint in the skull
Sympathetic division One of the two subdivisions of the autonomic nervous system concerned with reacting to emergency situations
Synapse The junction between two neurons
Synovial joint A fully moveable joint
System An association of organs that have a common function, e.g. digestive system, respiratory system
Systemic circulation The blood circulation from the left ventricl through the aorta to all the organs of the body and back to the heart
Systole The phase of the heartbeat involving contraction of the ventricles
Systolic blood pressure The blood pressure during passage of the pulse
Synapse The junction between two neurons
Synovial joint A fully moveable joint