Module 1–3 Review: Cell biology, metabolism, nervous system, and endocrinology (Fill-in-the-Blank)

Fill-in-the-blank flashcards covering key concepts from cell biology, metabolism, nervous system, and endocrinology.

The cell membrane is composed almost entirely of lipids and .

proteins

The lipid bilayer functions by impeding the movement of water-soluble substances because water is not soluble in .

lipids

Cell cytoplasm consists of the jelly-like substance that fills a cell and surrounds its internal structures - Consists of the fluid (cytosol) & various .

organelles

Endoplasmic reticulum (ER): a network of tubular & flat, vesicular structures in the cytoplasm. ER proteins & lipids in the cell.

synthesizes

Mitochondria: 'Powerhouse' of the cell; The site of digestion.

nutrient

Oxidative phosphorylation: The final and most significant phase of cellular respiration, where ATP is generated in the .

mitochondria

The metabolic pathway in which cells use enzymes to oxidize nutrients, thereby releasing chemical energy in order to produce ATP is called .

oxidative phosphorylation

Lysosomes provide enzymes for the cells to digest. Pathological causes of autolysis include: .

ischemia, trauma, and infections

Peroxisomes contain oxidase enzymes and form hydrogen used to detox many poisonous substances in the cell.

peroxide

Ribosomes synthesize new in the cell.

proteins

5 basic substances that make up a cell: Water, Electrolytes (or ions), Proteins, Lipids, and .

Carbohydrates

3 important/major parts of the cell: 1. Cell membrane 2. Cytoplasm 3. .

nucleus

Two purposes of the endoplasmic reticulum (ER): 1. Helps process molecules made by the cell 2. those molecules to their destinations inside or outside of cell.

transports

Functions of the Golgi apparatus: 1. Delivers cell surface receptors to the cell surface 3. Then, packages & delivers them to the cell surface ➢ Extracts energy from the food that you eat ➢ Oxidative phosphorylation ➢ Damaged cellular structures ➢ Food ➢ Unwanted matter (such as bacteria ➢ Ischemia ➢ Trauma ➢ Infections ➢ Lysosomal storage diseases

(Note: Golgi function card)

ATP is formed from ADP & .

phosphoric acid

If oxygen is NOT available, or if in really low supply, these oxidative reactions cannot take place ➢ In this case, glycolysis occurs.

anaerobic

Anaerobic glycolysis: occurs when little or no oxygen is available for necessary oxidative reactions, therefore only a small amt. of energy is released to cells ➢ Glucose is broken down into pyruvic acid, & then further to lactic acid (lactic acidosis)

pyruvic acid

Nucleus: the control center of the cell ➢ Enclosed by a nuclear membrane ➢ Stores hereditary info in genes; genes composed of DNA. Apoptosis: suicidal program cells undergo when they are no longer needed ➢ Programmed replacing of cells ➢ Natural process; orderly ➢ Cell is eaten by macrophages (a WBC) – phagocytosed by immune cells Abnormal apoptosis: caused by abnormal either activation or deactivation of the cell growth ➢ Can exist in cancer or autoimmune disease ➢ Abnormalities can also lead to various diseases: necrosis

DNA

Necrosis: a cell death that occurs due to acute injury or inflammation; is unexpected ➢ Produce angiogenic factors to generate blood vessels; which supply nutrients to cancer cells to grow/survive ➢ Don’t respect cellular growth limits ➢ Our human immune system typically destroys cancer cells, but gene mutations can lead to development ➢ Mutations can be a result of ionizing radiation or chance

unexpected

Metabolism: The chemical process of breaking down food & its transformation into energy ➢ Before entering cells: carbs converted into by digestive system; Proteins to amino acids; Fats to fatty acids

glucose

Then, once inside the cells (like mitochondria), they react chemically w/ oxygen guided by enzymes (an oxidative reaction) ➢ Energy released is used to form high energy compound: ATP ➢ Metabolic waste (byproducts) of oxidative reactions include: urea, H2O, & CO2

ATP

Metabolic reactions are regulated by hormones. ATP is the energy “currency” for all the reactions inside the cell. 1. A nitrogenous base (“adenine”) 2. A sugar molecule (“ribose”) 3. 3 phosphate radicals: “TRI-phosphate” (bound to ribose) ➢ 2 of the 3 necessary phosphate radicals in ATP are connected to the remainder of molecule by high energy phosphate bonds

phosphate

With the help of energy from food, ATP is formed from ADP ➢ When ATP splits to form ADP, the energy released is utilized for various cell functions: 1. Membrane transport 2. Chemical synthesis ➢ ATP is formed from the recombination of ADP & phosphoric acid w/ the help of energy derived from food

phosphoric acid

A chemical reaction w/ oxygen is very important for the initial energy to be released by food (fuels: carbs/fats/proteins) to create ATP ➢ BUT, if oxygen is NOT available, or if in really low supply, these oxidative reactions cannot take place ➢ In this case, anaerobic glycolysis occurs

oxygen

Conversely, when oxygen is scarce, glucose is broken down into pyruvic acid, then lactic acid (lactic acidosis) ➢ ↑ lactic acid=↓ oxygen to tissues (poor tissue perfusion)

lactic acid

The cell death that occurs to prevent cellular contents from spilling into body fluids is called apoptosis; necrotic cells burst open directly to the extracellular fluid (ECF)

apoptosis

The nucleus stores hereditary info in genes; genes composed of .

DNA

In a nerve fiber, K+ is greater inside & Na+ is greater outside: Equilibrium: In physiology, when chemical, pressure, & electrochemical gradients are equal & come to rest ➢ However, ions will be moving @ the same rate → this means that for every 1 ion moving out of the cell, 1 ion will move into the cell, when at equilibrium; the net movement is ZERO in equilibrium

Equilibrium

Equilibrium potential: the electrical potential (either a - or + charge) that exactly opposes the net diffusion of a particular ion across the cell membrane down its concentration gradient (SEE NEXT PAGE)

equilibrium potential

The nerve membrane has a channel protein called the “K+ leak channel” ➢ The difference in permeability in these channels is important in determining the level of normal resting membrane potential (RMP)

K+ leak channel

Na+-K+ pump: an electrogenic pump that transports more Na+ outside & less K+ inside, to maintain a “negative potential” inside the cell membrane ➢ Also causes & maintains a large concentration gradient for Na+ & K+ across the resting nerve membrane

Na+-K+ pump

Resting membrane potential (RMP): the electrical potential energy (or the electrical charge difference) across the cell membrane, when it is at rest or is not transmitting signals ➢ REMEMBER: Potassium is the most important factor in deciding RMP!!

-90 mV

Saltatory conduction: AP generated @ one point on the membrane excites adjacent portion, resulting in propagation of AP ➢ AP actually “jumps” from one node to another; nodes between the myelin sheaths are called of Ranvier

nodes

Myelin Sheath: a LIPID/PROTEIN substance that acts as an electrical insulator around an axon; promotes conduction & thus, faster conduction of impulses

saltatory

The autonomic nervous system (ANS) often operates through visceral reflexes and includes the Enteric nervous system (ENS); in the SNS, the adrenal medulla contains special neurons that secrete epi & norepi into the bloodstream

enteric nervous system

The PSNS exits via the Vagus nerve (X) & CONTROL ALL thoracic & abdominal organs; 75% of PSNS fibers are in X

Vagus nerve

Neurotransmitters: CHOLINERGIC nerve fibers secrete acetylcholine (ACh); ADRENERGIC nerve fibers secrete norepinephrine; pre-ganglionic neurons are CHOLINERGIC in BOTH the SNS & PSNS

acetylcholine

Catecholamines: Stress hormones such as epi/adrenaline & norepi/noradrenaline; a surge from adrenal medulla occurs during severe stress; this is part of the SNS response

epinephrine

The hypothalamus has integrative functions in the nervous system and controls autonomic responses via the brainstem, hypothalamus, and cortex; it also processes afferent information for reflexes

hypothalamus

Synaptic transmission steps include: vesicles filled with neurotransmitter fuse with presynaptic membrane, neurotransmitter released into synaptic cleft, and binding to receptors on the postsynaptic membrane; this is followed by receptor-mediated ion channel opening and post-synaptic potential generation

chemical synaptic transmission

Post-synaptic membrane: the neuron after the synapse; contains specific Nt receptors; EPSP makes the neuron more likely to fire; IPSP makes it less likely

post-synaptic

Excitatory Post-synaptic Potential (EPSP): a less negative value in the postsynaptic potential that moves toward threshold; typical threshold example: -45 mV

EPSP

Inhibitory Post-synaptic Potential (IPSP): an increase in negativity beyond resting potential; hyperpolarization; example value: -70 mV

IPSP

The motor end plate is the area where the motor neuron terminal synapses with the muscle fiber; includes presynaptic terminal, synaptic cleft, and postsynaptic membrane

motor end plate

Acetylcholinesterase: the enzyme that rapidly breaks down ACh in the NMJ

acetylcholinesterase

The NMJ endplate potential (MEPP) is a depolarization of the muscle cell membrane caused by the release of ACh from the motor neuron

MEPP

Excitation-Contraction Coupling (ECC): the process by which Ca2+ triggers the contractile elements in muscle cells; Ca2+ is pumped back into the SR after contraction

ECC

Skeletal muscle fibers are organized into motor units; a large motor unit innervates many fibers for gross contractions, while fine control uses fewer fibers per motor neuron

motor unit

3 muscle fiber types: Skeletal, Smooth, and Cardiac; skeletal muscles are innervated by the somatic nervous system

skeletal

Sarcoplasm: the intracellular fluid inside the sarcolemma; SR stores Ca2+ required for contraction; T-tubules propagate AP into the center of the muscle fiber

Sarcoplasm

Excitation-contraction coupling in skeletal muscle begins when the AP travels along the sarcolemma and T-tubules, causing VG-Ca2+ channels in the SR to open and Ca2+ to flood near the myofibrils

Ca2+ release from SR

Myosin heads form cross-bridges with actin to produce contraction; tropomyosin blocks active sites on actin until Ca2+ binds to troponin, moving tropomyosin and exposing active sites

cross-bridges

The sliding filament mechanism explains muscle contraction: actin and myosin filaments slide past one another, shortening the sarcomere

sliding filament mechanism

Power stroke: the mechanical event where myosin pulls actin, causing movement of the filament and contraction

power stroke

The ATP requirement for muscle contraction means there are 4 fuel sources inside muscle cells: ATP, Phosphocreatine, Glycogen, and .

Glycogenolysis

Smooth muscle differs from skeletal muscle in that it uses a latch mechanism to maintain contraction with less energy and has slower cross-bridge cycling

latch mechanism

Smooth muscle can be stimulated by multiple inputs: ANS (both SNS and PSNS), hormones, local factors, and stretch; Ca2+ comes primarily from the extracellular fluid in smooth muscle

Ca2+ source in smooth muscle

In smooth muscle, norepinephrine causes vasoconstriction; withdrawal of SNS activity can cause vasodilation; this is a key feature of vascular smooth muscle control

vasodilation

Mechanoreceptors, thermoreceptors, nociceptors, chemoreceptors, and electromagnetic receptors are sensory receptor types; sensation requires transduction of a stimulus into an action potential

sensory receptors

Somatosensory cortex areas: Area I has a high degree of localization; Area II has poorer localization; the lip and hand representations are large

localization

Pain pathways: the brain can suppress pain via the brainstem pathways; pain signals travel via cranial nerves IX and X for suppression

IX and X nerves

Endocrinology: Hormones are chemical messengers secreted by glands into the blood and regulate cellular function; hormones can be lipophilic (steroid) or hydrophilic (peptide)

hormone solubility

Steroid hormones (e.g., cortisol, aldosterone) are lipid-soluble and require carrier proteins to be transported in blood

lipid-soluble

Peptide hormones (e.g., insulin, glucagon) are water-soluble and act on cell-surface receptors

water-soluble

Thyroid hormones (T3 and T4) are derived from tyrosine and are soluble.

lipid

The HPAA axis comprises Hypothalamus → Anterior pituitary → Adrenal gland; oxytocin and ADH are neurohormones released from the posterior pituitary

hypothalamic-pituitary-adrenal axis

Cortisol increases blood glucose via glycogenolysis and has permissive effects on .

catecholamines

Aldosterone is regulated primarily by the system.

RAAS

The primary regulator of PTH is serum .

calcium

PTH increases serum calcium by promoting bone breakdown and stimulating renal production of Vitamin D; Vitamin D promotes intestinal absorption of calcium

calcium; Vitamin D

In the blood, about 50% of Ca2+ is in the free ionized form; albumin levels affect the measured total calcium

ionized

Acidosis can cause hypercalcemia by increasing H+ competition for protein binding sites, which frees more Ca2+ to be in the form.

ionized

Insulin promotes glucose uptake into _ and also drives K+ into cells in exchange for H+.

cells

Islets of Langerhans: Alpha cells secrete ; Beta cells secrete insulin.

glucagon

Diabetes mellitus involves an imbalance of insulin and glucagon; Type 1 is an absolute deficiency of insulin, Type 2 is insulin resistance with secretory deficit

insulin

Normal extracellular K+ (ECF K+) is about mEq/L.

4.2

Osmotic diuretics (e.g., Mannitol) increase urine output by drawing water into the renal tubules; examples include Mannitol, glycerol, isosorbide, urea, and .

glucose

1 osmole of solute dissolved in 1 kg of water corresponds to 1 .

osmolality

Osmolality normal range for adults is about 285–295 mOsm/kg; the kidney regulates acid-base balance via buffering systems primarily with bicarbonate (HCO3−) reabsorption

osmolality; bicarbonate

3 buffer systems include chemical buffers, respiratory buffers, and buffers.

renal

Gastrointestinal module content not provided in detail on this page; focus remains on physiology concepts above.

module 3.1 content