aEssays Flashcards
(21 cards)
Generation of action potential
An action potential has two main phases; a depolarization phase – sodium through the voltage gated Na+ channels through the cell membrane intro the cell à the negative membrane potential becomes less negative, reaches zero and then becomes positive. During the repolarization phases, potassium ions through the voltage gated K+ channels out of the cell, and then the membrane potential is restored to the resting state of -70 mV. Following this phase, there may be an after-hyperpolarization phase, during which the membrane potential temporarily becomes more negative than the resting potential
List examples of the participations of nucleotides, nucleosides or their derivate in important biological processes in addition to their serving as building blocks for nucleic acids
Nucleotides are organic molecules that serve as the subunits of nucleic acids like DNA and RNA. Composed of a nitrogenous base, a 5-carbon sugar, and at least one phosphate group. Nucleotides serve to carry packets of energy – ATP – within the cell. In form on nucleoside triphosphate nucleotides play a central role in metabolism, and participate in cell signalling. Nucleosides can produce nucleotides
Breathing is intermittent. What factors ensure that haemoglobin is saturated continuously in the lungs?
The partial pressure of oxygen to which haemoglobin is exposed is high in the lungs. Therefore, the oxygen binds readily to present haemoglobin.
Compare neurocrine, paracrine and endocrine communication
Neurocrine communication uses the nerve cell as signal/signal source. The signal reaches the target cell through the synaptic cleft. The signal reaches only the postsynaptic cell. Signal is called mediator or transmitter – transmit signals from a neuron to a cell across a synapse.
Paracrine communication: A cell produces a signal to induce changes in nearby cells. Uses many different types of cells as signal source, and the interstitial space as channel. The signal is sometimes called tissue hormones.
Endocrine communication: Collection of cells or glands secretes hormones directly into the bloodstream – channel. Reaches all cells of the body and the signal is called hormone
What kind of transmitter substances do you know – synapses
Acetylcholine – decrease heart rate
Norepinephrine – regulates activity of visceral organs
Epinephrine
Dopamine – control of certain motor functions
Serotonin – involved in mental functions
Adenosine
Synapse: In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell
Edema in legs and other parts of the body can cause chronic cardiac failure:
In right-sided heart failure, the cause can be edema that commonly starts in the ankles were venous pressure is high due to the effect of gravity
Edema in the lungs can cause respiratory fatigue and failure, which can lead to sudden cardiac death or arrhythmia
Water compartments – barriers – movements (of a substance through the membrane):
Water is located in compartments, which are surrounded by barriers that regulate movement. The barriers are the cell membrane and endothelium. The main regulator of the compartments is the kidney. Input/output through the extracellular compartment is drinking, urination, feces and breathing. The balance of input/output is very important. If we don’t have balance, cholera, diarrhoea, water poising occurs
The immune system response: Innate and adaptive
The innate immune system:
When cells are damaged or stressed, they send signals, many of which are recognized by the same receptors as those who recognize pathogens. Innate leukocytes identify and eliminate pathogens.
The adaptive immune system:
Allows a stronger immune response, as well as immunological memory, where each pathogen is “remembered” by a signature antigen. This response is maintained in the body by memory cells. Should a pathogen infect the body more than once, these specific cells are used quickly to eliminate it
Tissues:
Tissues are an assembly of specially differentiated cells
Epithelial tissue:
- Is usually one-layered, but multi-layered if it has to resist mechanical or osmotic stress
- Functions to protect organs from organs for the external environment an from microorganisms, injury and fluid loss
Connective tissue:
- Made up of cells separated by the extracellular matrix, and gives shape to organs and hold them in place (blood, bone)
- Forms: bone, blood, cartilage, tendon, adipose tissue
Nervous tissue:
- Made up of cells comprising the central and peripheral nervous system
- Function to transmit messages in form of impulse
- Composed of neurons and glia cells
Muscle tissue:
- Has the ability to contract and to conduct electrical synapses
- 3 types of muscle:
Smooth muscle (smooth), skeletal muscle (striated), cardiac muscle (striated)
Respiratory adaption:
Gas exchange control the rate or respiration
Central regulation: Inspiratory and expiratory neurons in the medulla
Output: Motor neurons innervating the diaphragm and the intercostal muscles
Trigger for inspiration: Increase of CO2 NH+ Decrease of O2 Trigger for expiration: Stretch receptors in the lungs
Muscles of respiration
The diaphragm is responsible for 45% of the air that enters the lungs during quiet breathing. During inhalation the diaphragm contracts, thus enlarging the thoracic cavity. When the diaphragm relaxes, air is exhaled. The internal intercostal muscles are responsible for about 25% of the air that enters the lungs during quiet breathing. These muscles are attached between each rib and are important in changing the width of the thoracic cage. The internal intercostal muscles assist in expiration by pulling the ribcage down. Accessory muscles are only used when the body needs to process energy quickly, for example during strenuous exercise or an asthma attack
The heart adapts to an increase in peripheral resistance
The heart cannot pump out the same volume against the increased resistance, which results in an increase in the end systolic volume. This leads to a stronger contraction and a new equilibrium à increased volume pumped
Hemoglobin saturation in the lungs
O2 affinity of haemoglobin controls plasma concentration. O2 affinity depends on chain composition of Hgb. The partial pressure of oxygen to which haemoglobin is exposed, is high in the lungs, therefore the oxygen binds readily to present haemoglobin
Blood pressure in the walls of arterioles
The blood pressure depends on the resistance to flow presented by the blood vessels. The mean blood pressure decreases as the circulating blood moves away from the heart through arteries and capillaries due to viscous loss of energy
The somatic nervous system
A part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles
Sympathetic: Aids in the control of most of the body’s internal organs. There are two kinds of neurons involved in the transmission of any signal through the sympathetic system: pre- and post-ganglionic
Parasympathetic: Responsible for stimulation of “rest and digest” activities that occur when the body is at rest, especially after eating (urination, digestion)
à Not every organ receives both parasympathetic, and sympathetic fibres. Body wall – only sympathetic. Local reflexes - parasympathetic
Parts/function of the lung
The chest contains of two lungs, one on the right side of the chest, and one on the left side. Each lung is made up of sections called lobes. Parts of the lung: Teaches, lobe, bronchioles, alveoli, diaphragm. The lung is soft and protected by the ribcage. The lungs’ function is to pull in oxygen and push oxygen into the chambers of the heart. Also to remove CO2
Interstitial fluid:
Interstitial fluid (tissue fluid) is a solution that bathes and surrounds the cells of multicellular animals. It is the main component of the extracellular fluid. The interstitial fluid is found in the interstitial spaces. On average, a person has about 10 litres of interstitial fluid, providing the cells of the body with nutrients and a means of waste removal
Can starving cause edema?
Yes. One example is children that are suffering from starving that has huge bellies. This edema is a result of a lack of protein in the bloodstream. The proteins in the bloodstream cause water to remain in the bloodstream. As the concentration of proteins in the bloodstream decreases, the water moves out of the bloodstream and into the extracellular spaces. Disruption of osmotic balance. This causes edema
Cardiac cycle:
The cardiac cycle is a term referring to all or any of the events related to all or any of the events related to the flow or blood pressure that occurs from the beginning of one heartbeat to the beginning of the next. The frequency of the cardiac cycle is described by the heart rate. A single cycle of cardiac activity can be divided into two basic phases - diastole and systole.
Systole: the portion of the heartbeat when the heart muscle is contracting
Diastole: portion of the heartbeat when heart muscle is relaxed and ventricles are filling with blood
Fluid mosaic model:
According to this model, all biological membranes are built up by a lipid bilayer where proteins float in the horizontal direction. The membrane lipids allow passage of several types of lipid-soluble molecules but act as a barrier to the entry or exit of charged or polar substances. Some of the proteins in the plasma membrane allow movement of polar molecules and ions into and out of the cell. Other proteins can act as signal receptors or adhesion molecules
Muscle types:
Three types of muscle tissue:
Cardiac muscle tissue (involuntary movement, striated)
Smooth muscle tissue (involuntary movement, smooth)
Skeletal muscle tissue (voluntary movement, striated)
Involuntary muscles such as the heart or smooth muscles in the gut contract as a result of non-conscious brain activity or stimuli proceeding in the body to the muscle itself
Voluntary muscle contraction is controlled by the CNS. The brain sends signals in form of action potentials, through the nervous system to the motor neuron that innervates several muscle fibres
