OTHER HALF (lectures 21-26) Flashcards
Study for the MCQ and exam prep in cells to organisms
What is negative feedback?
negative feedback helps organisms return to a normal range (eg temperature regulation, blood glucose)
- VERY important for homeostasis
What is positive feedback?
It amplifies stimulus and there are only a very small number of functions that it deals with (childbirth, blood clotting, electrical pulsing in nerves)
What is feedforward?
anticipatory response to expected change (e.g. increased heartrate in anticipation of exercise; increase of insulin secretion before food arrives)
What are the different places in the body that water is stored?
- intracellular fluid (ICF)
- Extracellular fluid (ECF)
- plasma
- interstitial fluid (ISF)
What is the nervous system and what is it composed of?
Network of specialized cells (neurons that transmit signals along dedicated paths)
- hard-wired
- fast acting (milliseconds)
- electrical and chemical signaling
- local cellular response
- rapid response by target cell
What is the endocrine system?
chemical signaling by hormones:
- hormones are transported in blood
- slower acting (minutes, hours, days)
- chemical signaling, often involves change in gene expression
- slower and often long-lasting responses of target cell
What are the steps of action in the central nervous system?
- Sensory reception
- Transduction
- Transmission
- Perception
- response
What are the parts of the brain for the central nervous system (CNS)?
- Brain
- Spinal chord
What are the parts for the peripheral nervous system?
- Cranial nerves
- Ganglia outside CNS
- Spinal nerves
What is in the brainstem?
It consists of - the midbrain, the pons, and the medulla oblongata
- the midbrain receives and integrates sensory information and sends it to specific regions of the brain
What does the Medulla do?
- controls several basic functions such as breathing, heart and blood vessel activity, swallowing and vomiting and digestion
What is the function of the cerebellum?
- Coordinates movement and balance and helps in learning and remembering motor skills
What is the function of the hypothalamus?
- Constitutes a control center that includes the body’s thermostat and central biological clock (overlap with endocrine system)
What is the function of the cerebrum?
controls skeletal muscle contraction and is the center for learning, emotion, memory and perception
What is the motor system (part of the PNS)?
The motor system carries signals to skeletal muscles and is mainly voluntary. (note reflexes, diaphragm breathing)
What is the autonomic nervous system (part of the PNS)?
It regulates smooth and cardiac muscles and is generally involuntary.
What are the parts of the two-neuron chain?
- Preganglionic fiber (synapses with cell body of second neuron)
- Postganglionic fiber (innervates effector organ)
What is a Ganglion?
A collection of cell bodies in the peripheral nervous system (equivalent is like the nucleus)
What happens in an action potential?
A release of a certain amount of neurotransmitter molecules
- the information is coded by frequency of AP firing
What happens when there is an increase in frequency during an action potential?
An increase means that there is more neurotransmitter released: bigger effect of target cells
What are the steps of action potential?
- Reception (signaling molecule signals the receptor)
- Transduction (relay molecules in a signal transduction pathway)
- Response (activation of cellular response)
What are motor neurons?
They are the final pathway were various regions of the CNS exert control over skeletal muscle activity.
What are the areas that motor neurons have control over?
- Spinal chord, motor regions of the cortex, basal nuclei, cerebellum, and brain stem
What is Acetylcholinesterase?
It activates ACh, and ends the end-plate potential and the action potential and resultant contraction
What does Black widow venom do?
Causes explosive release of ACh: prolonged depolarization - respiratory failure
What does Botulinum toxin do?
Blocks the release of ACh: causes flaccid paralysis
- Food poisoning; Medical use; Cosmetic use
What is the autonomic nervous system composed of?
It achieves all of its affects with 2 neurotransmitters: ACh and NAd (noradrenaline)
NOTE: epinephrine=adrenaline and norepinephrine=noradrenaline
Where are ACh and NAd secreted from?
- ACh is secreted from pre-ganglionic
- NAd is secreted from post-ganglionic
What are the different receptor types?
- Cholinergic receptors - bind ACh
- Nicotinic receptors - found on postganglionic cell bodies of all autonomic ganglia
- Muscarinic receptors - found on effector cell membranes
- Adrenergic receptors - bind noradrenaline and adrenaline
What does the hypothalamus do in terms of CNS?
The hypothalamus plays an important role in integrating autonomic, somatic and endocrine responses that automatically accompany various emotional and behavioral states.
What does a bronchodilator do?
Physiology: sympathetic nerves innervate bronchial smooth muscle, when they release NAd (eg during exercise): the bronchioles widen and makes it easier to breathe
- bronchodilator drugs act on these receptors to mimic the effect of endogenous neurotransmitter widening the bronchioles
What is a b-blocker and what does it do?
Beta blockers block the effects of sympathetic nerves, decreasing heart rate and helping to lower blood pressure.
What are common neurotransmitters (lowkey a lot)?
Acetylcholine, dopamine, Noradrenaline, Adrenaline, Serotonin, Histamine, Glycine, glutamate, aspartate, gamma-aminobutyric
What are diseases/disorders connected to Dopamine?
- Parkinson’s disease, schizophrenia and affective disorders
What are diseases/disorders connected to Serotonin?
Depression and emesis
What are the three types of muscle tissue in vertebrates?
- Skeletal muscle - also known as striated muscle, responsible for voluntary movement
- Smooth muscle - involuntary body movement
- Cardiac muscle - responsible for the contraction of the heart
What do paired muscles do?
Paired muscles are antagonistic (kind of opposite), and they are coordinated by the nervous system. They work cooperatively (good example is the lungs, or biceps and triceps)
What does locomotion mean?
The movement through space
What does the skeletal muscle consist of?
Skeletal muscle moves bones and the body, composed of smaller units:
each skeletal bundle consists of a bundle of long fibers, each a single cell running along the muscle.
What are myofibrils, and what do they look like?
Muscles fibers are arranged in smaller units called myofibrils, they are patterned in dark and light bands
What does the smallest unit of muscle look like?
the smallest unit is called a sarcomere and they are bordered by z lines where the filaments attach
What is the sliding filament model? (this could be drawn to help answer)
It shows an alternating between dark and light bands and there are the Z parts on the outside and the M on the inside of the band.
Why does the muscle fatigue?
lack of substrate (ATP) or accumulation of metabolites that interfere with contraction
How is muscle contraction dependent on calcium?
When the muscle is at rest tropomyosin and troponin bind to actin, this prevents actin and myosin from interacting.
- for the muscle site to contract the myosin-binding sites must be exposed
- It can be exposed when calcium binds to the troponin complex and expose the myosin-binding sites
- Contraction occurs when the concentration of calcium is high and muscle contraction stops when the calcium concentration is high
How does the skeletal muscle begin to contract?
It is dependent on muscle nerves, the stimulus leading to muscle contraction is an action potential
- the synaptic terminal releases (ACh)
- ACh depolarizes the muscle (end-plate potential), causing it to produce action potential
What are the two ways that the nervous system can create graded (not all the way) muscle contraction?
- varying the number of fibers that contract
- varying the rate at which the fibers are stimulated
What is Tetanus?
Also known as tetanic contraction: a physiological term describing sustained muscle contraction where a muscle doesn’t relax between contractions (when you are weight lifting)
What are some examples of skeletal muscle disorders?
- Amyotrophic lateral sclerosis/Motor Neurone disease
- Myasthenia gravis (attacks ACh receptors on muscle fibers
- Multiple sclerosis
- Duchenne Muscular Dystrophy
What is the cardiac muscle composed of?
Striated cells electrically connected by intercalated disks that contain gap junctions (electrical currents spread from one cells to another)
Why can the cardiac muscle generate action potentials without neural input?
This is because of the pacemaker in the heart
Why does the cardiac muscle not fatigue?
It has lots of mitochondria
Where are smooth muscles mainly found?
In the walls of hollow organs: like in the circulatory, digestive and reproductive systems
What are contractions in smooth muscles like?
Contractions are relatively slow and can be initiated by muscles themselves, they can also be stimulated by neurons in the autonomic nervous system (stomach from stress loll)
What happens when you don’t use your muscles?
You can get muscular atrophy, which is the loss or thinning of muscles bc you don’t use them
What are the classes of hormones?
There are three major classes:
1. Polypeptides
2. Steroids
3. Amines
How do water-soluble hormones work?
They are secreted by exocytosis, and travel freely in the bloodstream (makes sense)
How do Lipid-soluble hormones work?
They diffuse across cell membranes, travel in the bloodstream bind to transport proteins, and diffuse through the membrane of target cells.
What are considered endocrine glands? (where endocrine cells are found)
This would be the thyroid, and parathyroid glands. Along with the testes or ovaries
What are the steps to a simple endocrine pathway?
- Stimulus
- endocrine cell releases a hormone
- Hormone circulates through the body
- Targets cells
- Response
What is the Pituitary gland?
Made of the posterior and anterior pituitary
What does the posterior pituitary gland do?
Stores and secretes hormones that are made in the hypothalamus
- ADH, oxytocin
What does the anterior pituitary gland do?
it makes and releases hormones under regulation of the hypothalamus
- FSH, TSH, ACTH, Prolactin, MSH, GH
What do the testes primarily synthesize?
Androgens, which promote the development of male reproductive structures
What are the primary pancreatic hormones?
- endocrine cells
b-cells - alpha cells
Insulin and glucagon
What is the most common endocrine disorder?
Diabetes is the most common,
two major types: type 1 diabetes and type 2
What is the blood composed of?
Water, Ions (blood electrolytes), plasma proteins, immunoglobins, apolipoproteins, substances transported by blood
How big is the human heart?
The size of a clenched fist F
How long is the cardiac cycle?
It is about 0.8 seconds long, which means that the average heartrate is 75bpm
How is backward flow prevented in the heart?
It is prevented by the atrioventricular valve (AV) and semilunar valves.
What part of the nervous system slows the heart?
the parasympathetic division
What part of the nervous system accelerates the heart?
The Sympathetic division
What are the steps for the heart to be initiated by the pacemaker?
- Signals from SA node spread through atria
- Signals are delayed at AV node
- Bundle branches pass signals to heart apex
- Signals spread throughout the ventricles
What are abnormal heartrates called?
Fast: Tachycardia
Slow: Bradycardia
What is the structure of blood vessels from largest to smallest?
- ventricle
- artery
- arteriole
- capillary
- venule
- vein
- atrium
How does hemodynamics work?
Fluids move from regions of higher pressure to lower pressure down a pressure gradient
What is gas exchange in the capillaries?
It is the uptake of O2 from the environment and the discharge of CO2 to the environment
What happens to the lungs when you inhale?
The diaphragm contracts (moves down). Lung volumes increases: pressure in lung decreases below atmospheric pressure
What happens to the lungs when the lungs exhale?
Diaphragm relaxes (moves up). lung volume decreases: pressure in lungs is above atmospheric pressure.
What is Spirometry?
it is a pulmonary function test and a method of measuring the lung volumes. (but is dependent on patient effort)
How do gases diffuse in the lungs?
Gasses diffuse down pressure gradients, high pressure to low pressure
Where are the breathing controls found in the body?
breathing controls are found in the medulla oblongata of the brain, breathing is involuntary
- The medulla regulates the rate and depth of breathing in response to pH changes in the cerebrospinal fluid
What is hypoxia?
Low levels of oxygen in your tissues (can result in altitude sickness)
What are lymph vessels?
They are tubes that carry lymph through the body to lymph nodes and back to veins
What are major functions of lymph vessels?
- Tissue drainage
- Return leaked plasma proteins
- Absorption of digested fat
- Defense (lymph nodes)
What is oedema?
The build-up of fluid in the interstitium, via reduced plasma proteins
- loss in urine (kidney disease)
- reduced synthesis (liver disease)
- Dietary
Increased capillary permeability
- inflammation and allergic responses
Increased venous pressure
- uterine venous compression during pregnancy
Lymph blockage
What does osmoregulation do?
Balances the uptake and loss of water solutes
- plasma composition is regulated by the kidneys (urine is filtered plasma)
What is the process of osmoregulation? (steps)
- Filtration: filtering of plasma
- Reabsorption: reclaiming valuable solutes
- Secretion: adding nonessential solutes and wastes to the filtrate
- Excretion: processed filtrate containing nitrogenous wastes is released from the body
What does the proximal tubule do in blood filtration?
The proximal tubule reabsorbs ions, water and nutrients. Molecules are transported actively and passively from the filtrate into the interstitial fluid and then capillaries, materials excreted become concentrated.
What is the descending limb of the loop of Henle?
Reabsorption of water continues through channels formed by aquaporin proteins, movement is driven by high osmolarity - filtrate becomes even more concentrated
What is the ascending loop of Henle and what does it do?
Salt but not water is able to diffuse from the tubule into the interstitial fluid, then the filtrate becomes increasingly dilute
What does the Distal tubule and collecting duct do?
Distal tubule: regulates K+ and NACI concentrations, helps with pH regulation.
Collecting Duct: carries filtrate through the medulla to the renal pelvis important task (reabsorption of solutes and water)
What is the antidiuretic hormone?
Also known as the ADH, also called vasopressin - ADH molecules released from the posterior pituitary bind and activate membrane receptors on collecting ducts. This increases water recapture and reduces urine volume.
