Calcium and Potassium: Effects on Cardiac Function
Calcium Regulation
The normal level of calcium in the body is 9.4 mg/dl. Calcium is needed for muscle contraction and is regulated by hormonal secretion. Hypocalcemia is seen when levels are less than 8 mg/100 ml, and below 7 mg/100 ml, tetany occurs, causing muscle contraction and contracture, including major cardiac systole. Hypercalcemia is diagnosed when levels are over 12 mg/100 ml; this delays body functions, and the heart does not contract properly. Certain hormones are responsible for maintaining
Read MoreStimulus and Response: Nervous, Hormonal Systems
Stimulus and Response in Living Organisms
A stimulus is a change that occurs in the external or internal environment and provokes a response in the body. The relations function is carried out by coordination systems:
- Receptor organs (receive stimuli)
- Coordination centers (analyze information and elaborate a response)
- Effector organs (execute responses)
Coordination may be nervous or hormonal.
Nervous Coordination
The synapse is the functional union where the nervous impulse passes from one neuron to another
Read MoreHuman Body Tissues: Characteristics and Types
Tissues: General Characteristics, Histogenesis, and Classification
Tissues are a combination of cells and their products that have the following in common:
- Embryonal origin
- Morphology
- Functions
There are six general types of tissue in our body:
- Epithelial
- Connective
- Muscle
- Nerve
- Blood
- Reproductive
Epithelial Tissue
Epithelial tissue forms the border between the inner and outer environment.
- Covers surfaces in a uni- or multi-stratified manner.
- Almost no extracellular matrix (ECM).
- No blood supply.
- Functions include:
Understanding Genome Mutations, Aneuploidy, and Mutagenic Agents
Genome Mutations
Genome mutations affect the number of chromosomes characteristic of a species. These mutations appear to be related to abnormal segregation of chromosomes during meiotic division. We distinguish two main types: aneuploidy and euploidy.
Aneuploidy
Aneuploidy consists of a change in the number of chromosomes, either by gain or loss of one or more chromosomes. There are several types:
- Nullisomy: Missing a pair of homologous chromosomes (2n-2 chromosomes).
- Monosomy: Missing a single chromosome
Heart and Vessel Formation: A Detailed Look at Embryonic Development
Cardiovascular System Development
Cardiac Development
The cardiovascular system originates from the mesoderm. Around day 22 of development, a pair of heart tube structures forms, eventually fusing into a single heart tube composed of an inner endocardial tube and a surrounding myocardial layer. Between weeks 4 and 7, the heart develops into its characteristic four-chamber structure.
Formation of the Cardiac Septum
The heart’s septa develop from endocardial cushions in the atrioventricular canal and
Read MoreGenetics: Inheritance, Traits, and DNA Profiling
Genetics Fundamentals
Chromosomes and Genes
Homologous Chromosomes: Pairs of chromosomes with the same size, shape, and gene locations (one from each parent).
Gene: Basic hereditary unit, made of DNA sequences.
Alleles: Different forms of the same gene (e.g., yellow (Y) vs. green (y) seed color in peas).
Genetic Terminology
Homozygous: Two identical alleles for a gene (e.g., YY or yy).
Heterozygous: Two different alleles for a gene (e.g., Yy).
Dominant Allele: Expressed even if only one copy is present
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