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How does the body know blood calcium levels fall?
The PARATHYROID GLANDS release PARATHYROID HORMONE (PTH) in response to LOW CALCIUM levels in the BLOODSTREAM.
How does the body signal to effector organs to get more calcium?
When the PARATHYROID GLANDS release PARATHYROID HORMONE (PTH), PTH signals to EFFECTOR ORGANS (KIDNEYS and BONES). The kidneys prevent CALCIUM from being excreted in the URINE. OSTEOCLASTS in bones break down bone tissue to release calcium.
What breaks calcium free from bone?
OSTEOCLASTS use enzymes and acids to break down bone tissue to make room for newer, healthier bone, or to release calcium when calcium levels are low. (OSTEOBLASTS build bone. OSTEOCYTES are mature bone cells, regulating minerals and chemistry and additionally acting as endocrine cells.)
How does calcium get to the muscle tissue from the effector organs?
CALCIUM travels to muscle from the BONES and SMALL INTESTINE via the BLOODSTREAM.
What part of the muscle cell needs calcium and for what purpose?
CALCIUM triggers the contraction of the muscle by binding to TROPONIN, thus pulling TROPOMYOSIN off of the actin's binding sites for myosin. ACTIN and MYOSIN can now bind.
What process in the muscle tissue releases calcium?
An ACTION POTENTIAL generated by a MOTOR NEURON activates voltage-gated calcium channels, allowing CALCIUM to be released from the SARCOPLASMIC RETICULUM.
How does your body recognize what you are eating? (hint: 2 chemosensing organs are involved)
A molecule in the digestive system (like in a tastebud) has a RECEPTOR unit and a REPORTER unit. Different chemical components have different shapes that can only fit into certain receptors. These receptors are therefore specialized to only accept certain foods. They send this information to the brain through SENSORY NEURONS.
How does your body break down the macromolecules in the food?
ENZYMES in the digestive system break polymerous foods into their respective monomers. The STOMACH (PEPSIN), SMALL INTESTINE (NUCLEASE for nucleic acids, and CHYME), and PANCREAS all make digestive enzymes. The pancreas makes enzymes that break down proteins (PROTEASE), carbohydrates (AMYLASE), and fats (LIPASE).
Where does a majority of chemical digestion occur? Where do the enzyme come from?
Most digestion occurs in the SMALL INTESTINE. PANCREATIC ENZYMES mix with enzymes from the DUODENUM to break down polymers. CHYME from the small intestine gets thrown into the mix as well.
How do the amino acid monomers get from the digestive system to the blood?
ABSORPTION:
In the lower parts of the SMALL INTESTINE, amino acids are transported through the LUMEN, through INTESTINAL CELLS, to the BLOOD. This requires ATP and transport proteins (SODIUM-AMINO ACID TRANSPORTERS).
What binds to the amino acid to get it ready to be incorporated into a protein during translation?
tRNA binds to an amino acid, and carries it to the RIBOSOME, where the amino acids will be linked together in a chain.
What processes result in a protein being made for a cell?
TRANSLATION:
mRNA holds the instructions (CODONS) for how to make a protein. tRNAs, which have carried AMINO ACIDS over, read these codons. Each tRNA has an ANTICODON;. tRNAs bind to mRNAs inside of the RIBOSOME. This links the amino acids in a growing POLYPEPTIDE CHAIN.
What might happen if the DNA that instructs the synthesis of this protein is changed?
A change in DNA bases = a change in mRNA = different codons = different anticodons = different proteins synthesized.
How does your body sense change in light?
When light hits the RETINA, PHOTORECEPTORS (RODS and CONES), turn this light into ELECTRICAL SIGNALS. They feed this information to the GANGLION CELLS, and these cells send this information in the form of an ACTION POTENTIAL or NEURAL IMPULSE through the OPTIC NERVE to the OCCIPITAL LOBE.
How does your brain determine it is in danger?
A threat stimulus (like the sight of a predator), triggers the response of the AMYGDALA. The amygdala raises the alarm to the HYPOTHALAMUS, which in turn activates the SYMPATHETIC NERVOUS SYSTEM by sending signals through the AUTONOMIC NERVES to the ADRENAL GLANDS. Thusly, EPINEPHRINE (ADRENALINE) is released into the bloodstream. This speeds up HEART RATE, delivers more blood to parts of the body that need more OXYGEN, etc., in that epinephrine/adrenaline opens the airways and diverts blood and heart function.
(The PARASYMPATHETIC NERVOUS SYSTEM restores the body to a calm state. Together, this and the sympathetic nervous system make the AUTONOMIC NERVOUS SYSTEM.)
How does oxygen get from the air into your blood stream?
DIFFUSION:
In the lungs, BRONCHI branch into BRONCHIOLES. At the end of each bronchiole is a bundles of air sacs called ALVEOLI. OXYGEN moves from the alveoli to the BLOOD through CAPILLARIES lining the alveolar walls.
How is oxygen carried?
Once in the bloodstream, oxygen gets carried around by HAEMOGLOBIN (RED BLOOD CELLS).
How does oxygen get to a cell in your kidney?
OXYGENATED BLOOD travels to the KIDNEY via the LEFT and RIGHT RENAL ARTERIES of the HEART.
(DEOXYGENATED BLOOD leaves the kidney via the LEFT and RIGHT RENAL VEINS, whose blood enters the heart again through the heart's VENA CAVA.)
What purpose does oxygen have at the cellular level?
OXYGEN is required the final stage of CELLULAR RESPIRATION: OXYDATIVE PHOSPHORYLATION. Oxygen is the final electron acceptor of the ELECTRON TRANSPORT CHAIN inside of the MITOCHNDRIAL WALL. The electron transport chain creates energy through a series of REDOX REACTIONS, forming a PROTON GRADIENT. This energy is turned into ATP via the ATP SYNTHASE.
What happens if oxygen is not available to make ATP?
Without oxygen to make ATP, GLUCOSE is instead split into two molecules of PYRUVATE through GLYCOLYSIS. This only produces TWO ATP molecules, as opposed to CELLULAR RESPIRATION'S 38.
You cut your arm and it heals. What type of cell division occurs?
To heal a wound, skin cells replicate via MITOSIS.
Mitosis:
(Interphase)
Prophase - chromosomes pair up
Prometaphase
Metaphase - chromosomes line up along equator
Anaphase - sister chromatids are pulled apart
Telophase and Cytokinesis - cell pinches in the middle and two separate, identical daughter cells result
(Interphase)
Which cell-type is dividing in the epidermal layer to close the wound?
To close a wound, BASAL KERATINOCYTES (a type of EPITHELIAL CELL) at the wound edges are activated for MITOTIC DIVISION.
How do these cells with mutated DNA differ from other cells in the body?
POINT MUTATIONS:
Deletion: a nucleotide is deleted (non-frameshift = set of nucleotides divisible by three)
Insertion: a nucleotide is added (non-frameshift = set of nucleotides divisible by three)
Frameshift: addition or deletion of a nucleotide that leads to the chain being read differently
Silent: a mutation with no noticeable effect
Nonsense: mutation leads to a premature STOP codon
Missense: a nucleotide is changed
Note
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