Comprehensive Biology: Body Systems, Evolution, and Ecology

Flashcards covering human body systems (Integumentary, Respiratory, Circulatory, Lymphatic, Immune, Endocrine, Reproductive), along with Embryology, Animal Behavior, Ecology, Evolution, Skeletal, Muscular, Nervous, Digestive, and Renal systems based on lecture notes.

Stratum Corneum

The outermost hydrophobic layer of the epidermis.

Stratum Lucidum

A layer of the epidermis only present in the palms of hands and soles of feet.

Stratum Granulosum

The layer of the epidermis where skin cells lose organelles, begin dying, and are filled with keratin.

Stratum Spinosum

The layer of the epidermis that provides skin strength and flexibility; held together by desmosomes.

Stratum Basale

The deepest layer of the epidermis where new skin cells are formed.

Melanocytes

Epidermal cells that transfer skin pigment melanin to keratinocytes.

Merkel cells

Epidermal cells that attach to sensory neurons and function in touch sensations.

Keratinocytes

Epidermal cells that produce keratin and help waterproof the skin.

Langerhans cells

Epidermal cells that interact with immune cells.

Dermis

The second, highly vascularized layer of skin comprised of the papillary and reticular regions; connected to the epidermis via the basement membrane.

Papillary Region

A vascular network within the dermis containing upward projecting papillae with Meissner's corpuscles (sensory touch receptors) that supply nutrients to the epidermis and regulate temperature.

Reticular Region

A region of the dermis with dense connective tissue, collagen and elastic fibers; packed with glands, sweat gland ducts, fat, and hair follicles.

Hypodermis

Also known as the Subcutaneous layer; consists of areolar and adipose tissue functioning in fat storage, heat insulation, and shock absorption while containing pressure-sensing nerve endings.

Eccrine (Sudoriferous) glands

Glands located on the majority of skin that open directly to the surface to regulate temperature through perspiration and urea elimination.

Apocrine glands

Glands located in the armpits, pubic region, and nipples that open to hair follicles and produce more viscous secretions.

Sebaceous (Oil) glands

Glands connected to hair follicles that secrete sebum (oil) to discourage microbial growth.

Ceruminous (Wax) glands

Glands found in the ear canal that produce a wax-like material acting as an entrance barrier.

Mammary (Milk) glands

Specialized glands that secrete milk.

Desmosomes

Cell junctions that hold together cells in the Stratum Spinosum.

Larynx

The voice box; if non-gas enters, the cough reflex is activated.

Trachea

A structure covered by the epiglottis during swallowing containing C-shaped ringed cartilage covered by cilia and mucus cells.

Alveoli

Small sacs at the end of bronchioles surrounded by capillaries; the site of gas exchange via diffusioncoated with surfactant.

Surfactant

A coating on alveoli that reduces surface tension.

Bicarbonate ($HCO_3^-$)

The main buffer molecule in blood, transported in plasma to maintain a specific pH.

Carbonic anhydrase reaction

$$CO_2 + H_2O \rightleftharpoons H_2CO_3 \rightleftharpoons H^+ + HCO_3^-$$

Hemoglobin

A protein structure with 4 polypeptide subunits complexed around an $Fe$ atom that transports $O_2$.

CADET mnemonic

A memory aid for conditions that shift the $O_2$ dissociation curve RIGHT: $CO_2$, Acid, 2,3-DPG, Exercise, and Temperature.

Medulla oblongata

The respiratory control center of the brain that stimulates ventilation rate when partial pressure of $CO_2$ increases.

Central chemoreceptors

Receptors located in the medulla that indirectly monitor $[H^+]$ in cerebrospinal fluid.

Peripheral chemoreceptors

Receptors located in the carotid arteries and aorta that monitor concentrations of $CO_2$, $O_2$, and pH via $H^+$.

Goblet cells

Respiratory epithelium cells that secrete mucus.

Countercurrent exchange

A mechanism in fish where water and blood flow in opposite directions across gills to maximize diffusion of $O_2$ and $CO_2$.

Atrioventricular valves

Valves including the Tricuspid (right) and Bicuspid/Mitral (left) that connect atria to ventricles.

Semilunar valves

Valves including the Pulmonary (right ventricle to pulmonary artery) and Aortic (left ventricle to aorta).

SA node

The Sinoatrial (pacemaker) node in the upper right atrium that initiates the contraction of atria.

Bundle of His

A structure that passes the electrical impulse between ventricles to the Purkinje fibers.

Purkinje fibers

Fibers that receive signals from the Bundle of His and cause the contraction of both ventricles.

Systole

The contraction of atria or ventricles.

Diastole

The relaxation of atria or ventricles.

Pulmonary artery

The vessel with the lowest $O_2$ concentration in the body.

Pulmonary vein

The vessel with the highest $O_2$ concentration in the body.

Arterioles

Small branches of arteries wrapped in smooth muscle that serve as major determinants of blood pressure.

Precapillary sphincters

Structures that regulate the passage of blood into capillaries by relaxing to increase flow or tightening to reduce it.

Serum

Plasma without clotting proteins.

Platelets

Blood components responsible for clotting.

Agglutination

The clumping of blood cells that occurs when antibodies attack foreign antigens during an incompatible blood transfusion.

O-

The universal donor blood type because it has no antigens and does not trigger an immune response.

AB+

The universal recipient blood type as it does not produce antibodies against any blood type.

Lymph

Interstitial fluid absorbed into lymphatic vessels, originally forced out of capillaries as plasma.

Thymus

A central lymphoid tissue responsible for T-cell maturation.

Bone Marrow

A central lymphoid tissue that produces lymphocytes and contains stem cells for all leukocytes.

Spleen

A peripheral lymphoid tissue that filters blood as it passes through.

Adenoids

Masses of lymphatic tissue that inspect incoming food and air for pathogens.

Peyer's Patches

Large aggregates of lymphoid tissue located in the small intestine.

Edema

Swelling caused by a blocked lymphatic system where fluid pools in tissue.

Neutrophils

Phagocytic leukocytes that destroy pathogens in infected tissues; the most abundant leukocyte.

Monocytes

Leukocytes that circulate in blood and move into tissues via diapedesis to become macrophages.

Diapedesis

The process by which monocytes move from blood into tissues.

Mast cells

Non-phagocytic leukocytes involved in allergic responses, inflammatory responses, and anaphylaxis.

Interferons

Proteins secreted by infected cells to stimulate neighboring cells to defend against viral infections.

Cytokines

Chemical signaling molecules used for cell-cell communication in the immune response.

Toll-like receptors (TLRs)

Innate immunity proteins that recognize molecular patterns on pathogen surfaces and link innate and acquired immunity.

Epitopes

Specific parts of an antigen to which an antibody binds.

Clonal selection

The process where a foreign antigen activates a B cell, causing it to proliferate into Plasma Cells and Memory Cells.

Cytotoxic T cells

Killer T cells that destroy infected cells by releasing perforin protein and via lysis.

MHC I

Major Histocompatibility Complex molecules found on all nucleated cells that present antigens from inside the cell.

MHC II

Major Histocompatibility Complex molecules found only on Antigen Presenting Cells (APCs) that present antigens from outside the cell.

Active immunity

Immunity acquired after direct exposure to a pathogen (natural) or a vaccine (artificial).

Passive immunity

Immunity acquired from external sources, such as antibodies from a mother (natural) or serum injection (artificial).

Endocrine signaling

Signaling that targets a distant cell through the bloodstream.

Peptide hormones

Hormones that bind to surface cell membrane receptors and trigger pathways via secondary messengers.

Steroid hormones

Lipid-soluble hormones that diffuse across the plasma membrane and bind receptors in the cytoplasm to act transcriptionally in the nucleus.

Secondary messengers

Small molecules (e.g., $IP_3$, $cAMP$, $Calcium$, $DAG$) that amplify signal strength from ligand-receptor binding.

ACTH

A tropic hormone from the anterior pituitary that stimulates the adrenal cortex to release glucocorticoids.

ADH (vasopressin)

A hormone stored in the posterior pituitary that increases water reabsorption by increasing nephron collecting duct permeability.

Glucagon

A hormone secreted by Alpha cells of the pancreas that raises blood glucose levels.

Insulin

An anabolic hormone secreted by Beta cells of the pancreas that lowers blood glucose levels.

Mineralocorticoids

Hormones like aldosterone, secreted by the adrenal cortex, that increase $Na^+$ reabsorption and $K^+$ excretion to raise blood pressure.

PTH (parathyroid hormone)

A hormone that raises blood $Ca^{2+}$ levels by stimulating osteoclasts and increasing kidney/gut absorption.

Calcitonin

A hormone that lowers blood $Ca^{2+}$ by stimulating osteoblast activity to build bone.

Germ cell

A diploid cell of embryonic origin that gives rise to gametes (e.g., spermatogonium).

Ovoviviparity

A reproductive strategy where internally fertilized eggs hatch inside the mother, and young receive nutrients from the egg yolk.

Sertoli cells

Cells stimulated by FSH that nurture sperm within the seminiferous tubules.

Leydig cells

Also called interstitial cells; they secrete testosterone and androgens when stimulated by LH.

Acrosome

A lysosome-like organelle in the sperm head that digests through the zona pellucida of the egg.

SEVEN UP

Mnemonic for sperm pathway: Seminiferous tubules, Epididymis, Vas deferens, Ejaculatory duct, (Nothing), Urethra, Penis.

hCG (human chorionic gonadotropin)

A hormone secreted by the placenta that maintains the corpus luteum after implantation.

Corona Radiata

The outermost layer of the egg that sperm must swim through.

Capacitation

A biochemical process in the female reproductive tract that makes sperm more active.

Slow block to polyspermy

A long-lasting block triggered by $Ca^{2+}$ release that hardens the zona pellucida (fertilization membrane).

Differentiation

The physical change in a cell resulting from selective gene expression.

Determinate (mosaic) cleavage

Cleavage where the fate of the cell is decided early; a separated blastomere cannot form a complete organism.

Protostome

An organism characterized by spiral cleavage, determinate fate, and the mouth forming first from the blastopore.

Gastrulation

The stage of development where the blastula becomes a gastrula and forms the three germ layers: ectoderm, mesoderm, and endoderm.

Mesoderm

The germ layer that forms the circulatory, lymphatic, skeletal, and muscular systems, as well as the adrenal cortex.

Neurulation

The process where the notochord induces the ectoderm to form the neural tube, which becomes the brain and spinal cord.

Graylag goslings

The primary example used for imprinting, where they accept the first moving object seen as their mother.

Fixed action patterns

Instinctive behavior sequences initiated by sign stimuli that are completed even if the stimulus is removed.

Habituation

A learned decrease in response to a stimulus after repeated exposure without consequences.

Kinesis

Undirected change in movement speed in response to environment (e.g., fast in unfavorable conditions).