Human Physiology

Carbohydrates (75%): used for cell resp, short term energy storage; not essential Sources: monos in fruit; dis in sweet potato, bread; polys in whole grain, veggies Fiber (is a carb): in cell wall, not for absorption, in unprocessed foods Slows sugar absorption, stimulate bowel movement, limits bad bacteria Fatty acids (15%): long term energy storage, membrane growth; omega-3 (leaves, fish) and omega-6 (seeds → corn) are essential Sources: saturated in animal products; unsaturated oils in fish/plants; trans fats, unnatural Cholesterol: unessential; animal foods / sat fats; dietary excess → coronary heart disease 2 types: good low density (LDL) and bad high density (HDL) Amino acids (10%): 10/20 are essential; in lean meats / fish / dairy, beans / lentils / nuts Health concerns cause developmental disabilities: phenylketonuria (pku) genetic mutation in enzyme, protein deficiency malnutrition causes few blood plasma proteins Minerals (element), vitamins (organic compounds are water or fat soluble)

Deficiency, excess, or imbalance of nutrients Starvation: body breaks down tissue for energy (carb → fat → muscle) Excess: obesity (high blood pressure, heart disease) Hypothalamus makes us feel full when hormones arrive: Small intestine (when food is there): PYY3-36 Pancreas (when blood glucose levels increase): insulin Adipose tissue (when amount of stored eat increases): leptin

Oral cavity: salivary amylase breaks down carbs, physical digestion of tongue and teeth Esophagus: no new chemicals, peristalsis muscles move food Stomach: holds 1 gallon of food 2-6 hours; rugae allow expansion, secretes hydrochloric acid to sterilize, lining replaced every 3 days, physical churning, pepsin for proteins, cardiac and pyloric sphincters Small intestine: holds food 5-6 hours, 6m long, 250m2 surface area; duodenum starts, pancreas (secretes bicarbonate to up pH and enzymes) and liver/gall bladder (secrete and hold bile to coat lipids) at top; 25-30 enzymes to help digest; building blocks absorbed into blood by active transport, facilitated diffusion, exocytosis; villi in mucosa layer, then circular muscle layer, then longitudinal muscle layer Intestinal villus: epithelial cells line microvilli in lumen; villus has capillary with large pores and lacteal to absorb lipoproteins (lipids with bile) Large intestine: 12-24 hours, 90% of water reabsorbed, bacteria produce gas and vitamins

Transports nutrients, O2, CO2, hormones, antibodies, waste products, heat No cells more than 2-3 cells away from capillary for diffusion 4-6 L of blood in average adult 55% plasma: liquid matrix with suspended cells, mostly water, electrolytes, plasma proteins, escorts for lipids, antibodies, pH buffers Erythrocytes (red blood cell): 99.8% of blood Biconcave shape, hemoglobin (protein with iron) carry oxygen to cells Leukocytes (white blood cells): fewer and larger than RBC Phagocytes: engulf foreign material Lymphocytes: produce antibodies Platelets: cell fragments aid in clotting with fibrin protein

Collects blood in atria → ventricles → pumped out Valves prevent back flow Cardiac muscle (smooth rather than striated / skeletal), thicker on left because it goes to the whole body Coronary arteries supply heart muscle Conduction fibers coordinate contraction of ventricle wall Myogenic cells: contract without signal from brain/nerves Sinoatrial node: top right atrium; pacemaker Atrioventricular node: center top wall, medulla in brain signals; delays impulse between atria and ventricle contractions Atherosclerosis: occlusion of coronary artery Artery wall bulges into small lumen, can impede blood flow or rupture and clot

Heart → artery → arteriole → capillary → venule → vein → heart Artery: thick / stiff with muscle fibers and elastin, high blood volume and pressure (even between pumps) Capillary: thin, branching, permeable Veins: thinner walls, low pressure, valves prevent backflow, flexible for muscle contractions to move blood

Epiglottis open in larynx, trachea, bronchi, bronchioles Alveoli: 100m2 surface area for gas exchange; high concentration gradient Type 1 pneumocyte (95%) line inside; type 2 pneumocyte (5%) secrete water (surfocant) to help oxygen dissolve and prevent collapse Pulmonary artery → capillaries around alveoli → pulmonary vein Inhalation: external intercostal muscles and diaphragm contract, volume of thoracic cavity up Exhalation: internal intercostal muscles contract, diaphragm relaxes, volume down CO2 transport: 7% as dissolved, 23% bound to amine group on hemoglobin, 70% bicarbonate

Immediate: increased cell resp → increased blood pH → brain signals diaphragm and intercostal muscles Long term: more efficient muscles, respiration, increased stroke and tidal volume, lower resting heart and ventilation rates

The steady state and physiological condition of the body Blood pH, carbon dioxide and blood glucose concentration, body temp, water balance Monitors levels of variable and changes via negative feedback loop Nervous system: thermoregulation by hypothalamus If temp increases: nerves activate sweat glands, dilate capillaries near skin → stops signal It temp decreases: skin capillaries restrict, shiver contractions use energy (make heat) → stop Short-term cold: red cheeks from blood heating Cold: thyroid gland secretes thyroxin, increasing metabolic rate of cells Endocrine system: blood glucose regulation If increase: beta cells in pancreas secrete insulin into blood → liver pulls glucose to store as glycogen, body cells take glucose for cell resp → low glucose levels → no insulin If low levels: alpha cells in pancreas secrete glucagon into blood → liver breaks down glycogen to glucose in blood → up glucose levels → alpha stops glucagon

Type 1: insulin dependent; 10%; appears in childhood Autoimmune disorder, immune system destroys beta cells Insulin injections Type 2: non-insulin dependent; 90%; any age Not enough insulin or target cells / receptors don’t respond to insulin Control with diet, exercise, meds

Humans adapted to 24-hour cycle Hypothalamus controls secretion of melatonin by pineal gland High levels of melatonin → drowsiness Falling levels of melatonin → wake up

Functions: sensory input, integration (with brain), motor output Types of neurons Sensory; info from environment to CNS, long axon Relay: in spinal cord and brain, integrate information, short axon Motor: impulse from CNS to effector cells, long axon Neuron is the basic unit of nervous system Nerve impulse in nerve cell body → through axon → to synapse / dendrite Reflex arc: shortest route Sensory neuron into goes to motor neuron and brain simulanteously

Starting at rest (NA+ out and K+ in by active transport); -70 mv 1) stimulus whacks dendrite → momentary change in permeability 2) sodium floods in → neurotransmitter out to synapse for next whack; 35 mv 3) potassium moves out in concentration gradient 4) sodium out, potassium in via active; -75 mv to -70 mv 5) back to resting; neurotransmitters back in Depolarization: from negative to positive Action potential: potassium leaves (peak) Hyper polarization: down / bounce to rest Threshold of -50 mv to fire; strong stimuli cause greater frequency of action potentials

Wrap around axons to speed nerve impulse Pump happens in gaps (nodes of ranvier); no depolarization Jumps are faster and use less energy (saltory reconduction)

1) action potential depolarizes membrane of presynaptic terminal (end of axon) 2) Na moving in causes Ca+2 to move in via facilitated diffusion 3) synaptic vesicles with neurotransmitters fuse with presynaptic membrane 4) neurotransmitters diffuse across synapse 5) neurotransmitter binds to channel in post-synaptic membrane → channel opens for something else to go through (may reach threshold) 6) neurotransmitter released from receptors → channels close 7) neurotransmitter degraded by enzyme, taken to presynaptic terminal in pieces CNS integration: each neuron has many synaptic connections Excitatory → toward threshold Inhibitory → prevents firing Neurotransmitter example: dopamine, serotonin

Pathogens: bacteria, viruses, fungi, parasites, cells 1st line of defense: Skin, mucous membranes, secretion (sweat) Non-specific Physical barrier / makes it uninhabitable 2nd line of defense: Phagocytes leukocytes ingest microbes and create inflammatory response Non-specific Limits spread of microbes before immune response 3d line of defense: Lymphocytes create antibodies (bind to foreign macromolecule and elicit immune response) Specific to invader

Microbe has specific antigen on outside Phagocyte engulfs microbe because the antigens are foreign Phagocyte has outer antigen binding sites → bind to t-cell → release cytokines @ b-cell B-cell binds to antigen on microbe → differentiates to memory cell and plasma cell (antibodies, attach to antigen prevent reproduction)

Testes: in scrotum; form sperm and testosterone / androgens Scrotum: fold of body with lower temp for testes Epididymis: on testes; sperm mature, become motile, stored Vas deferens: pathway of sperm upon ejaculation Seminal vesicle: behind bladder; gland secretes proteins and fructose for semen Bulbourethral gland: secretes mucus to neutralize acidic urine in urethra before sperm Prostate gland: under bladder; anticoagulant enzymes and sperm nutrients Roles of testosterone: Determines development of male genitalia in embryos Secondary sex characteristics in puberty Sex drive throughout lifetime

Ovary: has follicles, produces egg, estrogen, progesterone Oviduct (fallopian tube): collect egg at ovulation, site of fertilization, mores embryo to uterus Uterus: forms placenta during pregnancy Vagina: stimulates penis, birth canal Periods; Hypothalamus GnRH to pituitary gland → LH and FSH increase production and secretion of estrogen in ovary → estrogen and progesterone vascularize tissue in endometrium Spike in FSH and LH causes ovulation Corpus luteum: remaining ovary cells after oocyte released Progesterone increases after ovulation and causes thickened endometrium If not pregnant → corpus luteum breaks down → est and prog fall → menstruation

Spike proteins on HIV attach to receptors on t-cells and phagocytes Reverse transcriptase converts RNA to complementary DNA; high error rate Integrase splices viral DNA into nucleus DNA Cell DNA makes more viral RNA Ribosomes make proteins; protease cuts larger proteins All parts made → bud off from membrane Destroys t-cells in process → no antibodies → bad immune response Treatment is drug cocktails because it mutates quickly